Podlutskii, Mikhail Sergeevich

Saburov V., Kazakova E., Moiseev A., Kazakov E., Podlutskii M., Babina D., Korol M., Gorbatova I., Volkova P.

Podlutskii M., Babina D., Podobed M., Bondarenko E., Bitarishvili S., Blinova Y., Shesterikova E., Prazyan A., Turchin L., Garbaruk D., Kudin M., Duarte G.T., Volkova P.

In the original publication [...]

Volkova P., Prazyan A., Podlutskii M., Saburov V., Kazakova E., Bitarishvili S., Duarte G.T., Shesterikova E., Makarenko E., Lychenkova M., Ben C., Gentzbittel L., Kazakov E., Moiseev A., Diuzhenko S., et. al.

Barley is a resilient crop with high nutritional value and adaptability, making it a promising candidate for phytoremediation and space agriculture. The study presents a comprehensive multi-omics analysis of the impact of ionising radiation (IR) on barley seedlings, intending to identify candidate pathways for creating radiation-resilient barley plants. We found that different IR treatments (gamma, electron, proton, neutron) increased the intensity of protein catabolism and led to the attenuation of translation. The impact of IRs on protein synthesis and degradation was accompanied by rearrangements in energy metabolism and reallocation of nitrogen, probably due to enhanced protein catabolism. At least partially, those changes seem to fuel secondary metabolites production, including riboflavin, various phytoalexins, phytosiderophores, ferulic and sinapic acids, kaempferol, quercetin, nictoflorin, gallate, and podophyllotoxin. Many of these compounds have antioxidant or radioprotective properties. To focus on possible targets for gene editing, we identified genes differentially regulated after all types of IR exposure and potential transcription factors regulating secondary metabolism, including AP2/ERF, WRKY, bHLH, bZIP, MYB, and NAC families.

Prazyan A., Podlutskii M., Volkova P., Kazakova E., Bitarishvili S., Shesterikova E., Saburov V., Makarenko E., Lychenkova M., Korol M., Kazakov E., Moiseev A., Geras’kin S., Bondarenko E.

The development of adaptation strategies for crops under ever-changing climate conditions is a critically important food security issue. Studies of barley responses to ionising radiation showed that this evolutionarily ancient stress factor can be successfully used to identify molecular pathways involved in adaptation to a range of abiotic stressors. In order to identify potential molecular contributors to abiotic stress resilience, we examined the transcriptomic profiles of barley seedlings after exposure to γ-rays, electrons, and protons. A total of 553 unique differentially expressed genes with increased expression and 124 with decreased expression were detected. Among all types of radiation, the highest number of differentially expressed genes was observed in electron-irradiated samples (428 upregulated and 56 downregulated genes). Significant upregulation after exposure to the three types of radiation was shown by a set of ROS-responsive genes, genes involved in DNA repair, cell wall metabolism, auxin biosynthesis and signalling, as well as photosynthesis-related genes. Most of these genes are known to be involved in plant ROS-mediated responses to other abiotic stressors, especially with genotoxic components, such as heavy metals and drought. Ultimately, the modulation of molecular pathways of plant responses to ionising radiation may be a prospective tool for stress tolerance programmes.

Kazakova E., Gorbatova I., Khanova A., Shesterikova E., Pishenin I., Prazyan A., Podlutskii M., Blinova Y., Bitarishvili S., Bondarenko E., Smirnova A., Lychenkova M., Bondarenko V., Korol M., Babina D., et. al.

The stimulation of growth and development of crops using ionising radiation (radiation hormesis) has been reported by many research groups. However, specific genes contributing to the radiation stimulation of plant growth are largely unknown. In this work, we studied the impact of the low-dose γ-irradiation of barley seeds on the growth dynamics and gene expression of eight barley cultivars in a greenhouse experiment. Our findings confirmed that candidate genes of the radiation growth stimulation, previously established in barley seedlings (PM19L-like, CML31-like, and AOS2-like), are significant in radiation hormesis throughout ontogeny. In γ-stimulated cultivars, the expression of these genes was aligned with the growth dynamics, yield parameters, and physiological conditions of plants. We identified contrasting cultivars for future gene editing and found that the γ-stimulated cultivar possessed some specific abiotic stress-responsive elements in the promotors of candidate genes, possibly revealing a new level of radiation hormesis effect execution. These results can be used in creating new productive barley cultivars, ecological toxicology of radionuclides, and eustress biology studies.

Voronezhskaya V., Volkova P., Bitarishvili S., Shesterikova E., Podlutskii M., Clement G., Meyer C., Duarte G.T., Kudin M., Garbaruk D., Turchin L., Kazakova E.

Our understanding of the long-term consequences of chronic ionising radiation for living organisms remains scarce. Modern molecular biology techniques are helpful tools for researching pollutant effects on biota. To reveal the molecular phenotype of plants growing under chronic radiation exposure, we sampled Vicia cracca L. plants in the Chernobyl exclusion zone and areas with normal radiation backgrounds. We performed a detailed analysis of soil and gene expression patterns and conducted coordinated multi-omics analyses of plant samples, including transcriptomics, proteomics, and metabolomics. Plants growing under chronic radiation exposure showed complex and multidirectional biological effects, including significant alterations in the metabolism and gene expression patterns of irradiated plants. We revealed profound changes in carbon metabolism, nitrogen reallocation, and photosynthesis. These plants showed signs of DNA damage, redox imbalance, and stress responses. The upregulation of histones, chaperones, peroxidases, and secondary metabolism was noted.

Podlutskii M., Babina D., Podobed M., Bondarenko E., Bitarishvili S., Blinova Y., Shesterikova E., Prazyan A., Turchin L., Garbaruk D., Kudin M., Duarte G.T., Volkova P.

Chronic ionising radiation exposure is a main consequence of radioactive pollution of the environment. The development of functional genomics approaches coupled with morphological and physiological studies allows new insights into plant adaptation to life under chronic irradiation. Using morphological, reproductive, physiological, and transcriptomic experiments, we evaluated the way in which Arabidopsis thaliana natural accessions from the Chernobyl exclusion zone recover from chronic low-dose and acute high-dose γ-irradiation of seeds. Plants from radioactively contaminated areas were characterized by lower germination efficiency, suppressed growth, decreased chlorophyll fluorescence, and phytohormonal changes. The transcriptomes of plants chronically exposed to low-dose radiation indicated the repression of mobile genetic elements and deregulation of genes related to abiotic stress tolerance. Furthermore, these chronically irradiated natural accessions showed higher tolerance to acute 150 Gy γ-irradiation of seeds, according to transcriptome and phytohormonal profiles. Overall, the lower sensitivity of the accessions from radioactively contaminated areas to acute high-dose irradiation may come at the cost of their growth performance under normal conditions.

Gorbatova I.V., Kazakova E.A., Podlutskii M.S., Pishenin I.A., Bondarenko V.S., Dontsova A.A., Dontsov D.P., Snegirev A.S., Makarenko E.S., Bitarishvili S.V., Lychenkova M.A., Chizh T.V., Volkova P.Y.

Gamma (γ)-irradiation of plants at low doses can provoke a broad range of growth-stimulating effects. In order to reveal universal target genes that are involved in molecular pathways of radiation hormesis establishment, we studied nine barley cultivars for their tolerance to γ-irradiation of seeds. Four morphological traits were assessed in barley seedlings after γ-irradiation of seeds at 20 Gy. Nine cultivars were sorted according to the sensitivity to irradiation as γ-stimulated, “no morphological effect”, or γ-inhibited. Gene expression of 17 candidate genes was evaluated for the 7 most contrasting cultivars. Changes in expression of barley homologues of PM19L and CML31 were suggested as possible determinants of radiation hormesis effect. The possible role of jasmonate signaling in roots in radiation growth stimulations was revealed. Morphological analysis and gene expression study showed that the genetic background of a cultivar plays an important role in eustress responses to low-dose γ-irradiation of seeds.

Podlutskii M.S., Lukashenko S.N., Tomson A.V., Oudalova A.A.

Abstract The paper introduces a pilot study of tritium as an indicator of possible transfer of radionuclide contamination around a regional radioactive waste storage. The main goal of the study is to determine tritium levels (tritiated water and organically bound tritium) and compare them with radiostrontium concentration in environmental samples. A hypothesis is tested on a possibility of using tritium as a marker of possible migration ways for other radionuclides, on an example of strontium-90. The results show that tritium concentrations nearby the regional radioactive waste storage is below the detection level (7 Bq·l−1). The lowest level of tritiated water was 7±1 Bq·l−1, the highest - 78±8 Bq·l−1. For organically bound tritium, the lowest level was shown at 8±1 Bq·kg−1, the highest - 57±7 Bq·kg−1. Comparison of the tritium findings with strontium-90 radioactivity levels showed that sampling points with high levels of tritium and radiostrontium are located in the same areas.

Babina D., Podobed M., Bondarenko E., Kazakova E., Bitarishvili S., Podlutskii M., Mitsenyk A., Prazyan A., Gorbatova I., Shesterikova E., Volkova P.

Plant growth response to γ-irradiation includes stimulating or inhibitory effects depending on plant species, dose applied, stage of ontogeny and other factors. Previous studies showed that responses to irradiation could depend on ABA accumulation and signaling. To elucidate the role of ABA in growth and photosynthetic responses to irradiation, lines Col-8, abi3-8 and aba3 -1 of Arabidopsis thaliana were used. Seeds were γ-irradiated using 60Co in the dose range 50-150 Gy. It was revealed that the dose of 150 Gy affected germination parameters of aba3 -1 and Col-8 lines, while abi3-8 line was the most resistant to the studied doses and even showed faster germination at early hours after γ-irradiation at 50 Gy. These results suggest that susceptibility to ABA is probably more important for growth response to γ-irradiation than ABA synthesis. The photosynthetic functioning of 16-day-old plants mainly was not disturbed by γ-irradiation of seeds, and no indication of photosystem II photoinhibition was noticed, revealing the robustness of the photosynthetic system of A. thaliana. Glutathione peroxidase activity and ABA concentrations in plant tissues were not affected in the studied dose range. These results contribute to the understanding of germination and photosynthesis fine-tuning and of mechanisms of plant tolerance to ionizing radiation.

Kazakova Е.А., Makarenko Е.S., Podlutsky М.S., Dontsova A.A., Bitarishvili S.V., Lychenkova M.A., Gorbatova I.V., Filippov Е.G., Dontsov D.P., Chizh Т.V., Snegirev А.S., Volkova P.Y.

Barley is the main forage crop in the Russian Federation. Barley grain is also used for food and brewery (Filippov, 2013). It is common knowledge that low doses of gamma irradiation can have a stimulating effect on the growth and development of plants, in particular barley. However, there is a lack of knowledge about the molecular pathways responsible for the formation of the stimulation effect after low-dose seed irradiation. The use of varieties with different radio sensitivity to low-dose gamma irradiation will allow studying specific molecular mechanisms to form a stimulating irradiation effect. Such knowledge could further help in the development of varieties with a large stable productivity over the years and with high resistance to biotic and abiotic stressors. In 2019 there was conducted a gamma irradiation of the original seeds of nine winter and spring barley varieties developed in the FSBSI “Agricultural Research Center “Donskoy” in order to assess intensity of the response on low-dose ionizing irradiation based on changes in the morphological parameters of irradiated and unirradiated plants. The original seeds of each barley variety were irradiated at the FSBSI “All-Russian Research Institute of Radiology and Agroecology” by the gamma device “GUR-120” with 60Со radiation sources at a dose of 20 Gy (dose rate of 60 Gy/hour). The statistical data processing was performed by the Microsoft Office Excel 2019. The morphological analysis of the length and weight of roots and sprouts made it possible to establish the presence or absence of the stimulating irradiation effect on the studied indicators of the varieties and to conduct their subsequent ranking according to the value of the radiobiological effect. There have been identified the winter and spring barley varieties with different sensitivity to a dose of 20 Gy. The stimulating irradiation effect was established in such varieties as “Foks 1”, “Ratnik”, “Yerema” and “Master”. The variety “Leon” had an inhibitory irradiation effect.

Mylsamy P., Tamilmani E., Venugopal R., Murugaiyan S., Ranganathan U.

Abstract Cotton, a crucial commercial fibre crop, depends heavily on seed-associated characteristics like germination rate, vigour, and resistance to post-harvest deterioration for both production and lint quality. Serious cellular damage during post-harvest processes such as delinting, prolonged seedling emergence periods, decreased viability, increased susceptibility to infections, and lipid peroxidation during storage pose serious problems to seed quality. The performance of seeds and total crop productivity are adversely affected by these problems. Traditional methods of seed improvement, like physical scarification and seed priming, have demonstrated promise in raising cotton seed vigour and germination rates. Furthermore, modern approaches including plasma therapies, magnetic water treatments, and nanotechnology-based treatments have shown promise in improving seed quality and reducing environmental stresses. By offering sustainable substitutes for conventional approaches, these cutting-edge procedures lessen the need for fungicides and other agrochemicals that pollute the environment. This review explores various conventional and emerging strategies to address the detrimental factors impacting cotton seed quality. It emphasizes the importance of integrating classical and advanced approaches to enhance germination, ensure robust crop establishment, and achieve higher yields. In addition to promoting sustainable cotton production, this kind of integration helps preserve the ecosystem and create resilient farming methods.

Bitarishvili S., Clement G., Meyer C., Volkova P.

Al-Sayed W.M., El-Shazly H.H., El-Nahas A.I., Omran A.A.

Abstract Maize is the third most important grain crop worldwide after wheat and rice; it is a vital global crop, serving as a key source of food, animal feed, and industrial products, making it essential for food security and economic stability in many countries. Drought stress adversely affects water uptake and can stunt growth, reducing the overall productivity of maize. So, this study was carried out to investigate the cytogenetic effects of gamma radiation and drought stress on maize SC131 genotype, focusing on chromosomal aberrations in seedling root meristems induced by varying doses of gamma irradiation (50, 100, 150, 200, and 250 Gray) and drought stress imposed by 10% polyethylene glycol (PEG). The present study also aims to evaluate the impact of these treatments on growth parameters under a controlled pot experiment. Additionally, molecular polymorphism induced by both gamma irradiation and drought stress was analyzed using Real-Time quantitative PCR techniques for DREB2, ERF, and EF transcription factors. Also, under a field condition experiment, maize plants were subjected to the same gamma irradiation doses and drought stress by reducing the number of irrigations, with subsequent evaluations of yield attributes to assess the overall impact of treatments on plant performance. The study also investigates the sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE) banding patterns of proteins in grains yielded under the influence of gamma radiation and drought treatments. Findings of the current investigation indicate that the low dose of gamma radiation (50 Gray) not only induces cytogenetic changes but also enhances drought tolerance and improves yield characteristics, suggesting that targeted gamma irradiation could serve as a viable strategy to bolster maize resilience in challenging environmental conditions.

Grinberg M., Vodeneev V.

Plants will form the basis of artificial ecosystems in space exploration and the creation of bases on other planets. Astrophysical factors, such as ionizing radiation (IR), magnetic fields (MF) and gravity, can significantly affect the growth and development of plants beyond Earth. However, to date, the ways in which these factors influence plants remain largely unexplored. The review shows that, despite the lack of specialized receptors, plants are able to perceive changes in astrophysical factors. Potential mechanisms for perceiving changes in IR, MF and gravity levels are considered. The main pathway for inducing effects in plants is caused by primary physicochemical reactions and change in the levels of secondary messengers, including ROS and Ca2+. The presence of common components, including secondary messengers, in the chain of responses to astrophysical factors determines the complex nature of the response under their combined action. The analysis performed and the proposed hypothesis will help in planning space missions, as well as identifying the most important areas of research in space biology.

Timakova R.T., Gulova T.I.

The research literature studies the effect of different types of radiation on the viability and safety of grain crops. At the same time, there has been found a selective approach to the problem of using radiation and other abiotic factors, based on the goals in plant growing or in the food industry, which determined the complexity of the current work in estimating the effect of low doses of γ-radiation on the technological properties of grain, flour and bread, taking into account different doses of γ-radiation, controlled germination, whole grain milling. The primary object of the study was the grain of spring common wheat variety ‘Iren’. The wheat grains were irradiated at the “Era” RCOHS” using the RTU-3000 unit. Germination was carried out under controlled conditions. There has been estimated the effect of increasing the radiation dose to 20 Gy on enhancing the kinetics of grain germination and increasing the hardiness of the grain. There has been found that sprouted wheat grain bioactivated by radiation, which has improved nutritional value, can be used as a raw material for flour production and in bread baking. The obtained flour is of low moisture 9.1–9.2 %, which provides its better storage. There have been characterized regularities of uniform porosity, dense and elastic crumb of bread in whole-ground wheat bread samples baked from grain treated with low doses of radiation due to the greater amount of gluten (36.0–36.3 %) and its good quality, elastic properties of the dough. There has been found that in bread samples made from sprouted grain, due to the high quality of gluten (75–80 units of IDK) with lower porosity values compared to bread made from non-sprouted grain, the organoleptic properties of the bread fully comply with the established requirements for whole wheat bread. The results of the current study have shown the feasibility of using low doses of radiation, germination, and the use of whole-ground flour to form the consumer value of wheat bread.

Zhang Y., Wang W., Zhang M., Zhang B., Gao S., Hao M., Zhou D., Zhao L., Reitz G., Sun Y.

IntroductionHeavy ions of the galactic cosmic radiation dominate the radiation risks and biological effects for plants under spaceflight conditions. However, the biological effects and sensitive genes caused by heavy ions with different linear energy transfer (LET) values have not been thoroughly studied.MethodsTo comprehensively analyze the biological effects of heavy ions with different LET values on rice under spaceflight conditions, we utilized the Shijian-10 recoverable satellite (SJ-10) to transport the dehydrated rice seeds on a 12.5-day mission in a 252 km low Earth orbit (LEO), and obtained rice plants hit by individual heavy ions with LET values ranging from 18 keV/μm to 213 keV/μm. The transcriptome and methylation sequencing were conducted on above plants, and a bioinformatics pipeline based on single-sample networks (SSNs) and genetic algorithms (GA) was developed to analyze the multi-omics expression profiles in this work. Note that SSNs can depict the gene interaction patterns within a single sample. The LET regression models were constructed from both gene expression and interaction pattern perspectives respectively, and the radiation response genes that played significant roles in the models were identified. We designed a gene selection algorithm based on GA to enhance the performance of LET regression models.ResultsThe experimental results demonstrate that all our models exhibit excellent regression performance (R2 values close to 1), which indicates that both gene expressions and interaction patterns can reflect the molecular changes caused by heavy ions with different LET values. LET-related genes (genes exhibiting strong correlation with LET values) and radiation-responsive genes were identified, primarily involved in DNA damage and repair, oxidative stress, photosynthesis, nucleic acid metabolism, energy metabolism, amino acid/protein metabolism, and lipid metabolism, etc. DNA methylation plays a crucial role in responding to heavy ions stressors and regulates the aforementioned processes.DiscussionTo the best of our knowledge, this is the first study to report the multi-omics changes in plants after exposure to heavy ions with different LET values under spaceflight conditions.

Yu P., Shinde H., Dudhate A., Kamiya T., Gupta S.K., Liu S., Takano T., Tsugama D.

The pearl millet gene PgPM19 inhibits seed dormancy by negatively regulating the ABA biosynthesis and ABA signaling pathways in response to salinity stress in Arabidopsis. Abscisic acid (ABA) plays a pivotal role in orchestrating plant stress responses and development. However, how the ABA signal is transmitted in response to stresses remains primarily uncertain, particularly in monocotyledonous plants. In this study, PgPM19, a gene whose expression is induced by drought, salinity, heat, and ABA in both leaf and root tissues, was isolated from pearl millet. The expression of PgPM19 in yeast cells did not influence their growth when subjected to mannitol, sorbitol, or NaCl stress. However, Arabidopsis plants overexpressing PgPM19 (PgPM19_OE plants) exhibited increased germination rates, greater fresh weights and longer roots under salinity stress during germination, compared to wild-type (WT) plants. Conversely, the pm19L1 (SALK_075435) mutant, featuring a transfer DNA insertion in a closely related PgPM19 homolog (AT1G04560) in Arabidopsis, demonstrated reduced germination rates and smaller fresh weights under salinity-stressed condition than did WT and PgPM19_OE plants. A pivotal ABA biosynthesis gene, NCED3, ABA signaling pathway genes, such as PYL6 and SnRK2.7, alongside downstream ABI genes and stress-responsive genes RAB28 and RD29, were downregulated in PgPM19_OE plants, as evidenced by both transcriptome analysis and quantitative reverse transcription-PCR. These findings raise the possibility that PgPM19 is involved in regulating seed germination by mediating ABA biosynthesis and signaling pathway in response to salinity stress in Arabidopsis. This study contributes to a better understanding of PgPM19 in response to salinity stress and establishes a foundation for unraveling the crosstalk of stress responses and ABA in Arabidopsis and other plant species.

Bitarishvili S., Shesterikova E., Smirnova A., Volkova P., Duarte G., Geras’kin S.

The impact of chronic radiation exposure on phytohormone content and expression of phytohormone- and stress-related genes of Scots pine in the zone affected by the Chernobyl accident was studied. Needle samples were collected from three plots with contrasting levels of radioactive contamination in the Polesye State Radiation-Ecological Reserve, Republic of Belarus, and two reference plots in the Kozeluzhsky forest in June 2022. The experimental plots were located within the artificial plantations of Scots pine established in 1982, before the accident in 1986. The activity of radionuclides 137Cs, 90Sr, 241Am, 238Pu, and 239+240Pu in soil and needles ensured dose rates ranging from 3.3 to 87 mGy × year−1, while at the reference plots, the range was 0.7‒0.8 mGy × year−1. Concentrations of plant hormones, including indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), zeatin, and abscisic acid (ABA) in needles were evaluated using high-performance liquid chromatography (HPLC). We demonstrate that chronic radiation exposure is a significant stress factor that affects both phytohormonal balance and the expression of some important phytohormone- and stress-related genes. We found a tendency toward decreased ABA and auxin concentrations in trees from plots contaminated with radionuclides. The ratio (IAA + IBA + zeatin)/ABA was drastically raised at the most contaminated plots Masany and Kulazhin, reflecting the functional rearrangements of cellular metabolism that ensure plant adaptation under chronic radiation exposure. Changes in gene expression indicated modulation of ABA and Ca2+ signalling pathways, decreased potential of zeatin biosynthesis, and activation of heat shock proteins biosynthesis.

Panahi B., Hosseinzadeh Gharajeh N., Mohammadzadeh Jalaly H.

This review examines the transformative role of next-generation sequencing (NGS) technologies on barley breeding, emphasizing their potential to harness barley's extensive genetic diversity for enhancing global food security. Barley, as a key cereal crop, faces increasing challenges from climate change, disease, and food demands, making it crucial to develop resilient and productive cultivars. The study aims to provide a comprehensive overview of how NGS has revolutionized the identification of critical genetic variation and improved breeding efficiency, especially in relation to traits such as disease resistance, drought tolerance, and yield improvement. NGS technologies, including Genotyping-by-Sequencing and pan-genomics approaches, have significantly advanced our understanding of barley's genetic makeup by integrating genomic and phenotypic data, enabling deeper insights into trait expression and environmental adaptation. Additionally, the application of big data analytics and machine learning in breeding programs has optimized trait selection and breeding outcomes. Despite the remarkable progress, challenges persist, particularly in resource-limited regions, where the cost of NGS technologies and lack of bioinformatics infrastructure hinder widespread adoption. The review concludes that ongoing innovation in NGS and related technologies holds great promise for future barley breeding, presenting opportunities to further enhance crop resilience and productivity to meet the rising global agricultural demands.

Saburov V., Kazakova E., Moiseev A., Kazakov E., Podlutskii M., Babina D., Korol M., Gorbatova I., Volkova P.

Afonina S.O., Komarova L.N., Rasskazova M.M.

The effect of γ-irradiation (60Co) in the dose range from 2 to 50 Gy on the morphological (length of the sprout, length of the main root) and biochemical parameters (the content of photosynthetic pigments – chlorophyll a, chlorophyll b, carotenoids) of sprouts of irradiated seeds of common barley variety Vityaz was studied.

Manjarrez L.F., de María N., Vélez M.D., Cabezas J.A., Mancha J.A., Ramos P., Pizarro A., Blanco-Urdillo E., López-Hinojosa M., Cobo-Simón I., Guevara M.Á., Díaz-Sala M.C., Cervera M.T.

The maritime pine (Pinus pinaster Ait.) is a highly valuable Mediterranean conifer. However, recurrent drought events threaten its propagation and conservation. P. pinaster populations exhibit remarkable differences in drought tolerance. To explore these differences, we analyzed stem transcriptional profiles of grafts combining genotypes with contrasting drought responses under well-watered and water-stress regimes. Our analysis underscored that P. pinaster drought tolerance is mainly associated with constitutively expressed genes, which vary based on genotype provenance. However, we identified key genes encoding proteins involved in water stress response, abscisic acid signaling, and growth control including a PHD chromatin regulator, a histone deubiquitinase, the ABI5-binding protein 3, and transcription factors from Myb-related, DOF NAC and LHY families. Additionally, we identified that drought-tolerant rootstock could enhance the drought tolerance of sensitive scions by regulating the accumulation of transcripts involved in carbon mobilization, osmolyte biosynthesis, flavonoid and terpenoid metabolism, and reactive oxygen species scavenging. These included genes encoding galactinol synthase, CBL-interacting serine/threonine protein kinase 5, BEL1-like homeodomain protein, dihydroflavonol 4-reductase, and 1-deoxy-D-xylulose-5-phosphate. Our results revealed several hub genes that could help us to understand the molecular and physiological response to drought of conifers. Based on all the above, grafting with selected drought-tolerant rootstocks is a promising method for propagating elite recalcitrant conifer species, such as P. pinaster.

Mohammadi V., Zare Mehrjerdi M., Rastogi A., Gruda N.S., Aliniaeifard S.

Gamma radiation has been suggested to have post-effects on emerging plants when applied to the seeds. In the present study, we aimed to induce alterations in photosynthetic functionality and subsequent modifications in secondary metabolites of summer savory following seed priming with gamma radiation. Savory seeds were treated with 0, 50, 100, 200, and 300 Gy gamma radiation in a completely randomized design with ten replications for morphological and photosynthetic parameters and three for phytochemical assessments. The results showed that gamma radiation on seeds adversely affected photosynthetic performance, especially at the highest doses. It negatively influenced the growth, while increasing the shoot branching, the number of nodes, and the diameter of the stem. Gamma radiation on seeds generally reduced pigmentation in savory leaves, such as chlorophylls, carotenoids, and anthocyanins. However, soluble sugar, starch, total phenolics, and total flavonoid contents were elevated in the leaves of plants that emerged from gamma-primed seeds. Gamma radiation priming reduced essential oil’s percentage and yield. Carvacrol and limonene components of essential oil were diminished, whereas linalool and thymol were increased. In conclusion, due to its inherent stress-inducing effects, and despite some positive effects on phytochemicals, seed priming with gamma radiation adversely influenced growth, photosynthesis, and quantity and quality of savory essential oils. Further research is still needed to target the use of gamma radiations before harvesting the seeds or determine the cytogenetic characteristics of irradiated plants.

Ksas B., Chiarenza S., Dubourg N., Ménard V., Gilbin R., Havaux M.

AbstractIonising γ radiation produces reactive oxygen species by water radiolysis, providing an interesting model approach for studying oxidative stress in plants. Three‐week old plants of Arabidopsis thaliana were exposed to a low dose rate (25 mGy h−1) of γ radiation for up to 21 days. This treatment had no effect on plant growth and morphology, but it induced chronic oxidation of lipids which was associated with an accumulation of reactive carbonyl species (RCS). However, contrary to lipid peroxidation, lipid RCS accumulation was transient only, being maximal after 1 day of irradiation and decreasing back to the initial level during the subsequent days of continuous irradiation. This indicates the induction of a carbonyl‐metabolising process during chronic ionising radiation. Accordingly, the γ‐radiation treatment induced the expression of xenobiotic detoxification‐related genes (AER, SDR1, SDR3, ALDH4, and ANAC102). The transcriptomic response of some of those genes (AER, SDR1, and ANAC102) was deregulated in the tga256 mutant affected in three TGAII transcription factors, leading to enhanced and/or prolonged accumulation of RCS and to a marked inhibition of plant growth during irradiation compared to the wild type. These results show that Arabidopsis is able to acclimate to chronic oxidative stress and that this phenomenon requires activation of a carbonyl detoxification mechanism controlled by TGAII. This acclimation did not occur when plants were exposed to an acute γ radiation stress (100 Gy) which led to persistent accumulation of RCS and marked inhibition of plant growth. This study shows the role of secondary products of lipid peroxidation in the detrimental effects of reactive oxygen species.

Mishra S., Duarte G.T., Horemans N., Ruytinx J., Gudkov D., Danchenko M.

In nature, plants are simultaneously exposed to different abiotic (e.g., heat, drought, and salinity) and biotic (e.g., bacteria, fungi, and insects) stresses. Climate change and anthropogenic pressure are expected to intensify the frequency of stress factors. Although plants are well equipped with unique and common defense systems protecting against stressors, they may compromise their growth and development for survival in such challenging environments. Ionizing radiation is a peculiar stress factor capable of causing clustered damage. Radionuclides are both naturally present on the planet and produced by human activities. Natural and artificial radioactivity affects plants on molecular, biochemical, cellular, physiological, populational, and transgenerational levels. Moreover, the fitness of pests, pathogens, and symbionts is concomitantly challenged in radiologically contaminated areas. Plant responses to artificial acute ionizing radiation exposure and laboratory-simulated or field chronic exposure are often discordant. Acute or chronic ionizing radiation exposure may occasionally prime the defense system of plants to better tolerate the biotic stress or could often exhaust their metabolic reserves, making plants more susceptible to pests and pathogens. Currently, these alternatives are only marginally explored. Our review summarizes the available literature on the responses of host plants, biotic factors, and their interaction to ionizing radiation exposure. Such systematic analysis contributes to improved risk assessment in radiologically contaminated areas.

Liu K., Liang Z., Yang A., Yan J., Cong P., Han X., Zhang C.

Apple leaf spot, caused by the Alternaria alternata apple pathotype (AAAP), is an important fungal disease of apple. To understand the molecular basis of resistance and pathogenesis in apple leaf spot, the transcriptomes of two apple cultivars ‘Hanfu’ (HF) (resistant) and ‘Golden Delicious’(GD) (susceptible) were analyzed at 0, 6, 18, 24 and 48 hours after AAAP inoculation by RNA-seq. At each time point, a large number of significantly differentially expressed genes (DEGs) were screened between AAAP-inoculated and uninoculated apple leaves. Analysis of the common DEGs at four time points revealed significant differences in the resistance of ‘HF’ and ‘GD’ apple to AAAP infection. RLP, RNL, and JA signal-related genes were upregulated in both cultivars to restrict AAAP development. However, genes encoding CNLs, TNLs, WRKYs, and AP2s were only activated in ‘HF’ as part of the resistance response, of which, some play major roles in the regulation of ET and SA signal transduction. Further analysis showed that many DEGs with opposite expression trends in the two hosts may play important regulatory roles in response to AAAP infection. Transient expression of one such gene MdERF110 in ‘GD’ apple leaves improved AAAP resistance. Collectively, this study highlights the reasons for differential resistance to AAAP infection between ‘HF’ and ‘GD’ apples which can theoretically assist the molecular breeding of disease-resistant apple crops.

Yemets A., Shadrina R., Blume R., Plokhovska S., Blume Y.

AbstractAutophagy plays an important role in plant growth and development, pathogen invasion and modulates plant response and adaptation to various abiotic stress stimuli. The biogenesis and trafficking of autophagosomes involve microtubules (MTs) as important actors in the autophagic process. However, initiation of autophagy in plants under microgravity has not been previously studied. Here we demonstrate how simulated microgravity induces autophagy development involving microtubular reorganization during period of autophagosome formation. It was shown that induction of autophagy with maximal autophagosome formation in root cells of Arabidopsis thaliana is observed after 6 days of clinostating, along with MT disorganization, which leads to visible changes in root morphology. Gradual decrease of autophagosome number was indicated on 9th and 12th days of the experiment as well as no significant re-orientation of MTs were identified. Respectively, analysis of α- and β-tubulins and ATG8 gene expression was carried out. In particular, the most pronounced increase of expression on both 6th and 9th days in response to simulated microgravity was detected for non-paralogous AtATG8b, AtATG8f, AtATG8i, and AtTUA2, AtTUA3 genes, as well as for the pair of β-tubulin duplicates, namely AtTUB2 and AtTUB3. Overall, the main autophagic response was observed after 6 and 9 days of exposure to simulated microgravity, followed by adaptive response after 12 days. These findings provide a key basis for further studies of cellular mechanisms of autophagy and involvement of cytoskeletal structures in autophagy biogenesis under microgravity, which would enable development of new approaches, aimed on enhancing plant adaptation to microgravity.

Volkova P., Prazyan A., Podlutskii M., Saburov V., Kazakova E., Bitarishvili S., Duarte G.T., Shesterikova E., Makarenko E., Lychenkova M., Ben C., Gentzbittel L., Kazakov E., Moiseev A., Diuzhenko S., et. al.

Barley is a resilient crop with high nutritional value and adaptability, making it a promising candidate for phytoremediation and space agriculture. The study presents a comprehensive multi-omics analysis of the impact of ionising radiation (IR) on barley seedlings, intending to identify candidate pathways for creating radiation-resilient barley plants. We found that different IR treatments (gamma, electron, proton, neutron) increased the intensity of protein catabolism and led to the attenuation of translation. The impact of IRs on protein synthesis and degradation was accompanied by rearrangements in energy metabolism and reallocation of nitrogen, probably due to enhanced protein catabolism. At least partially, those changes seem to fuel secondary metabolites production, including riboflavin, various phytoalexins, phytosiderophores, ferulic and sinapic acids, kaempferol, quercetin, nictoflorin, gallate, and podophyllotoxin. Many of these compounds have antioxidant or radioprotective properties. To focus on possible targets for gene editing, we identified genes differentially regulated after all types of IR exposure and potential transcription factors regulating secondary metabolism, including AP2/ERF, WRKY, bHLH, bZIP, MYB, and NAC families.

Arikan B., Yildiztugay E., Ozfidan-Konakci C.

SA is a phytohormone that plays a key role in the regulation of the defense response against environmental variables in plants, and it provides increased yield and stress tolerance when exogenously applied to plants as a growth regulator. The role of SA-mediated signals in abiotic stress tolerance varies according to the species, stressor, application method, and dose. This study investigated the effects of salicylic acid (SA, 0.1 mg ml−1) or β-cyclodextrin encapsulated salicylic acid (e-SA, 0.1 mg ml−1) treatments on growth parameters, gas exchange, photosynthesis efficiency, and antioxidant capacity in lettuce seedlings exposed to polycyclic aromatic hydrocarbon pollution. Fluorene (FLN, 100 mg L−1) contamination resulted in a 27% growth rate and a 14% water content reduction in lettuce leaves. Significant suppressions of stomatal conductance, carbon assimilation, and PSII photochemistry were detected in plants under stress. FLN + SA and FLN + e-SA treatments regulated plant-water relations by stimulating proline accumulation and relieving stomatal limitations. As indicated by the high Fv/Fm ratio, photosynthesis efficiency was recovered in FLN + SA and FLN + e-SA group plants. FLN stress caused high oxidative stress in lettuce leaves and increased lipid peroxidation level by 40%. However, especially e-SA application to plants under stress, increased SOD activity by 3-fold and CAT activity by 80% and was successful in preventing H2O2 accumulation and lipid peroxidation. Both SA and e-SA treatments partially activated the AsA-GSH cycle. As a result, direct SA application was effective in mitigating stress-induced physiological limitations with high SA accumulation in the tissues, while encapsulated SA treatment was more effective in regulating photosynthetic and biochemical reactions, alleviating oxidative damage by activating the antioxidant defense, and promoting growth under stress with moderate SA accumulation.

Pixley K.V., Cairns J.E., Lopez-Ridaura S., Ojiewo C.O., Dawud M.A., Drabo I., Mindaye T., Nebie B., Asea G., Das B., Daudi H., Desmae H., Batieno B.J., Boukar O., Mukankusi C.T., et. al.

Climate change poses daunting challenges to agricultural production and food security. Rising temperatures, shifting weather patterns, and more frequent extreme events have already demonstrated their effects on local, regional, and global agricultural systems. Crop varieties that withstand climate-related stresses and are suitable for cultivation in innovative cropping systems will be crucial to maximize risk avoidance, productivity, and profitability under climate-changed environments. We surveyed 588 expert stakeholders to predict current and novel traits that may be essential for future pearl millet, sorghum, maize, groundnut, cowpea, and common bean varieties, particularly in sub-Saharan Africa. We then review the current progress and prospects for breeding three prioritized future-essential traits for each of these crops. Experts predict that most current breeding priorities will remain important, but that rates of genetic gain must increase to keep pace with climate challenges and consumer demands. Importantly, the predicted future-essential traits include innovative breeding targets that must also be prioritized; for example, (1) optimized rhizosphere microbiome, with benefits for P, N, and water use efficiency, (2) optimized performance across or in specific cropping systems, (3) lower nighttime respiration, (4) improved stover quality, and (5) increased early vigor. We further discuss cutting-edge tools and approaches to discover, validate, and incorporate novel genetic diversity from exotic germplasm into breeding populations with unprecedented precision, accuracy, and speed. We conclude that the greatest challenge to developing crop varieties to win the race between climate change and food security might be our innovativeness in defining and boldness to breed for the traits of tomorrow.

De Micco V., Amitrano C., Mastroleo F., Aronne G., Battistelli A., Carnero-Diaz E., De Pascale S., Detrell G., Dussap C., Ganigué R., Jakobsen Ø.M., Poulet L., Van Houdt R., Verseux C., Vlaeminck S.E., et. al.

AbstractLong-term human space exploration missions require environmental control and closed Life Support Systems (LSS) capable of producing and recycling resources, thus fulfilling all the essential metabolic needs for human survival in harsh space environments, both during travel and on orbital/planetary stations. This will become increasingly necessary as missions reach farther away from Earth, thereby limiting the technical and economic feasibility of resupplying resources from Earth. Further incorporation of biological elements into state-of-the-art (mostly abiotic) LSS, leading to bioregenerative LSS (BLSS), is needed for additional resource recovery, food production, and waste treatment solutions, and to enable more self-sustainable missions to the Moon and Mars. There is a whole suite of functions crucial to sustain human presence in Low Earth Orbit (LEO) and successful settlement on Moon or Mars such as environmental control, air regeneration, waste management, water supply, food production, cabin/habitat pressurization, radiation protection, energy supply, and means for transportation, communication, and recreation. In this paper, we focus on air, water and food production, and waste management, and address some aspects of radiation protection and recreation. We briefly discuss existing knowledge, highlight open gaps, and propose possible future experiments in the short-, medium-, and long-term to achieve the targets of crewed space exploration also leading to possible benefits on Earth.

De Micco V., Aronne G., Caplin N., Carnero-Diaz E., Herranz R., Horemans N., Legué V., Medina F.J., Pereda-Loth V., Schiefloe M., De Francesco S., Izzo L.G., Le Disquet I., Kittang Jost A.I.

AbstractAdvancements in plant space biology are required for the realization of human space exploration missions, where the re-supply of resources from Earth is not feasible. Until a few decades ago, space life science was focused on the impact of the space environment on the human body. More recently, the interest in plant space biology has increased because plants are key organisms in Bioregenerative Life Support Systems (BLSS) for the regeneration of resources and fresh food production. Moreover, plants play an important role in psychological support for astronauts. The definition of cultivation requirements for the design, realization, and successful operation of BLSS must consider the effects of space factors on plants. Altered gravitational fields and radiation exposure are the main space factors inducing changes in gene expression, cell proliferation and differentiation, signalling and physiological processes with possible consequences on tissue organization and organogenesis, thus on the whole plant functioning. Interestingly, the changes at the cellular and molecular levels do not always result in organismic or developmental changes. This apparent paradox is a current research challenge. In this paper, the main findings of gravity- and radiation-related research on higher plants are summarized, highlighting the knowledge gaps that are still necessary to fill. Existing experimental facilities to simulate the effect of space factors, as well as requirements for future facilities for possible experiments to achieve fundamental biology goals are considered. Finally, the need for making synergies among disciplines and for establishing global standard operating procedures for analyses and data collection in space experiments is highlighted.

Kim D., Nguyen Q.T., Lee S., Choi K., Lee E., Park J.Y.

AbstractOver the past few decades, research on life in space has increased. Owing to the expensive nature of and the challenges associated with conducting experiments in real space, clinostats, which continuously randomize the gravity vector by using motors, have been used to generate simulated microgravity (SMG) on Earth. Herein, by using a 3D printing method, we develop a customized small-sized clinostat (CS clinostat) that is easy to manufacture, inexpensive, and robust. Moreover, we develop and fabricate a gas-permeable polydimethylsiloxane culture dish that fits inside the CS clinostat. To validate SMG generation, ovarian cancer cells (OV- 90, TOV-21G, and Caov-3) were applied to demonstrate a significant reduction in caveolin-1 expression, a biomarker of SMG, indicating SMG generation. The proposed CS clinostat system has good accessibility for SMG research, which makes it useful as a tool for biologists, who are unfamiliar with conventional clinostat equipment, to conduct preliminary studies in the space environment.

Ishikawa E., Kanai S., Sue M.

Plants accumulate various secondary metabolites, and the biosynthetic reactions responsible for their scaffold construction are the key steps that characterize their structural categories. Gramine, an indole alkaloid, is a defensive secondary metabolite biosynthesized in barley (Hordeum vulgare) from tryptophan (Trp) via aminomethylindole (AMI). While the two sequential N-methylation steps following the formation of AMI have already been characterized both genetically and enzymatically, the step preceding AMI formation, which includes the Trp side chain-shortening, has not yet been revealed. To gain further insight into these biosynthetic reactions, barley seedlings were fed Trp labeled with stable isotopes (13C and 15N) at various positions, and the isotope incorporation into gramine was analyzed by liquid chromatography/mass spectrometry. Significant increases in the abundance of isotopic gramine were detected in experimental sets in which Trp was labeled at either the indole ring, the β-carbon, or the amino group, whereas the isotopolog composition was not affected by α-carbon-labeled Trp. Although absorbed Trp presumably undergoes transamination in plants, this reaction did not seem to be related to gramine productivity. The data indicated that AMI directly inherited the amino group from Trp, while the α-carbon was removed, suggesting that the Trp-AMI conversion includes a novel intramolecular rearrangement reaction. The results of this study provide novel insights into scaffold formation in plant secondary-metabolite synthesis.

Loy N.N., Sanzharova N.I., Kazakova E.A., Bitarishvili S.V.

The surveys were focused on assessing the opportunity for presowing treatment of barley seeds with low-energy electron beam radiation to improve the growth processes and to reduce the damage caused by phytopathogens. The laboratory experiment was carried out to study the impact of low-energy electron beam radiation (160 keV) at doses of 1 kGy, 3 kGy, and 5 kGy and a radiation dose rate of 500 Gy/imp on a range of plant parameters. They included seed germination characteristics and seedling morphometric traits along with the damage caused by fungal diseases at the reference of natural infection, enzyme activities, and phytohormone concentrations in 7-day-old seedlings. The seeds untreated with radiation were used to serve as a control group. Treatment at a dose of 3 kGy induced significant increases in the laboratory germination and the seed growth force by 6 and 10%, respectively, when compared to the control seed group. Irradiation at doses of 1 and 5 kGy did not have any effects on these parameter values. With respect to the doses of 1 and 5 kGy, increases in the lengths of a sprout and a rootlet by 6.8–8.2 and 5.9–24.6%, respectively were recorded, when compared to the control. A dose of 3 kGy had no effect on the values of these parameters. Irradiation had insignificant impacts on seedling’s fresh and dry mass and water contents in them. The electron beam radiation treatment of seeds at doses of 1, 3, and 5 kGy completely suppressed the spread of Penicillium spp. Irradiation at 3 and 5 kGy inactivated Fusarium spp. However, the treatment at a dose of 5 kGy is associated with a significant, 2.1-fold increase in the seedling damage caused by Bipolaris sorokiniana and a 1.8-fold increase in its spread. Irradiation had no impact on the activity of most enzymes and phytohormones in seedlings, except the 1.5- and 2.7-fold increases in the contents of indolylacetic and indolylbutyric acids at irradiation at 5 and 1 kGy, respectively, when compared to the control.

Fan P., Wu L., Wang Q., Wang Y., Luo H., Song J., Yang M., Yao H., Chen S.

Medicinal plants have a wide range of uses worldwide. However, the quality of medicinal plants is affected by severe cadmium pollution. Cadmium can reduce photosynthetic capacity, lead to plant growth retardation and oxidative stress, and affect secondary metabolism. Medicinal plants have complex mechanisms to cope with cadmium stress. On the one hand, an antioxidant system can effectively scavenge excess reactive oxygen species produced by cadmium stress. On the other hand, cadmium chelates are formed by chelating peptides and then sequestered through vacuolar compartmentalization. Cadmium has no specific transporter in plants and is generally transferred to plant tissues through competition for the transporters of divalent metal ions, such as zinc, iron, and manganese. In recent years, progress has been achieved in exploring the physiological mechanisms by which medicinal plants responding to cadmium stress. The exogenous regulation of cadmium accumulation in medicinal plants has been studied, and the aim is reducing the toxicity of cadmium. However, research into molecular mechanisms is still lagging. In this paper, we review the physiological and molecular mechanisms and regulatory networks of medicinal plants exposed to cadmium, providing a reference for the study on the responses of medicinal plants to cadmium stress.

Bitarishvili S., Dikarev A., Kazakova E., Bondarenko E., Prazyan A., Makarenko E., Babina D., Podobed M., Geras’kin S.

Cadmium leads to disturbance of plant growth, and the manifestation of toxicity can vary greatly in different genotypes within one species. In this work we studied the effect of Cd on growth, antioxidant enzyme activity, and phytohormonal status of four barley cultivars (cvs. Simfoniya, Mestnyj, Ca 220702, Malva). According to the earlier study on seedlings, these cultivars were contrast in tolerance to Cd: Simfoniya and Mestnyj are Cd-tolerant and Ca 220702 and Malva are Cd-sensitive. The results presented showed that barley plants accumulated more Cd in straw than in grain. Tolerant cultivars accumulated significantly less Cd in grain than sensitive ones. The leaf area appeared to be a growth parameter susceptible to Cd treatment. The significant differences in leaf area values depended on Cd contamination and were not associated with cultivars’ tolerance. Tolerance of cultivars was contingent on the activity of the antioxidant defense system. Indeed, activity of enzymes decreased in sensitive cultivars Ca 220702 and Malva under Cd stress. In contrast, in tolerant cultivars, increased activity of guaiacol peroxidase was revealed. The concentrations of abscisic acid and salicylic acid mostly increased as a result of Cd treatment, while the concentrations of auxins and trans-zeatin either decreased or did not change. The results obtained indicate that antioxidant enzymes and phytohormones play an important role in the response of barley plants to elevated concentrations of cadmium; however, these parameters are not able to explain the differentiation of barley cultivars in terms of tolerance to cadmium at the seedling stage. Therefore, barley intraspecific polymorphism for cadmium resistance is determined by the interplay of antioxidant enzymes, phytohormones, and other factors that require further elucidation.

Cuypers A., Vanbuel I., Iven V., Kunnen K., Vandionant S., Huybrechts M., Hendrix S.

Cadmium (Cd) is one of the most toxic compounds released into our environment and is harmful to human health, urging the need to remediate Cd-polluted soils. To this end, it is important to increase our insight into the molecular mechanisms underlying Cd stress responses in plants, ultimately leading to acclimation, and to develop novel strategies for economic validation of these soils. Albeit its non-redox-active nature, Cd causes a cellular oxidative challenge, which is a crucial determinant in the onset of diverse signalling cascades required for long-term acclimation and survival of Cd-exposed plants. Although it is well known that Cd affects reactive oxygen species (ROS) production and scavenging, the contribution of individual organelles to Cd-induced oxidative stress responses is less well studied. Here, we provide an overview of the current information on Cd-induced organellar responses with special attention to redox biology. We propose that an integration of organellar ROS signals with other signalling pathways is essential to finetune plant acclimation to Cd stress.

De Francesco S., Amitrano C., Vitale E., Costanzo G., Pugliese M., Arrichiello C., Ametrano G., Muto P., Arena C., De Micco V.

An adequate and balanced diet is fundamental in preserving the health of astronauts from several space-induced diseases. Therefore, the integration of a diet with fresh food, rich in bioactive compounds such as microgreens produced directly onboard, may be useful in space for human nutrition. However, ionizing radiation (IR) in space represents a significant hindrance for organisms, with potential critical outcomes on plant morpho-anatomical, eco-physiological, and biochemical aspects, depending on the plant and IR features (e.g., species, developmental stage, IR dose, and type). In this study, we analyzed the effect of different doses of X-rays (0-control, 0.3, 1, 10, 20, and 30 Gy) on the morpho-anatomical and nutritional traits of microgreens of Brassica rapa L., irradiated at the stage of germinated seeds. After the irradiation, microgreens were cultivated in controlled conditions. At harvest, the morpho-biometric traits were analyzed, along with the leaf functional anatomical traits and the phytochemical content of the aboveground biomass. The results showed that X-ray exposure does not induce detrimental effects on growth, while it stimulates the production of antioxidants, improving plant defense and nutritional value. The overall results support the idea of using this species in space as a supplemental functional food.

Li Z., Fu Z., Zhang S., Zhang X., Xue X., Chen Y., Zhang Z., Lai Z., Lin Y.

AbstractLongan (Dimocarpus longan Lour.) is an economically important subtropical fruit tree. Its fruit quality and yield are affected by embryo development. As a plant seed germination marker gene, the germin-like protein (GLP) gene plays an important role in embryo development. However, the mechanism underlying the role of the GLP gene in somatic embryos is still unclear. Therefore, we conducted genome-wide identification of the longan GLP (DlGLP) gene and preliminarily verified the function of DlGLP1-5–1. Thirty-five genes were identified as longan GLP genes and divided into 8 subfamilies. Based on transcriptome data and qRT‒PCR results, DlGLP genes exhibited the highest expression levels in the root, and the expression of most DlGLPs was upregulated during the early somatic embryogenesis (SE) in longan and responded to high temperature stress and 2,4-D treatment; eight DlGLP genes were upregulated under MeJA treatment, and four of them were downregulated under ABA treatment. Subcellular localization showed that DlGLP5-8–2 and DlGLP1-5–1 were located in the cytoplasm and extracellular stroma/chloroplast, respectively. Overexpression of DIGLP1-5–1 in the globular embryos (GEs) of longan promoted the accumulation of lignin and decreased the H2O2 content by regulating the activities of ROS-related enzymes. The results provide a reference for the functional analysis of DlGLPs and related research on improving lignin accumulation in the agricultural industry through genetic engineering.