Genetic diversity and population structure assessment of Indian bitter gourd accessions using nutritional content and molecular markers

Bitter gourd (Momordica charantia L.) is a nutritionally rich vegetable and the demand for bitter gourd with high nutritional value may have increased due to rising consumer knowledge about phytonutrient content and health. We characterized 45 genotypes comprising of 3 wild species, 14 landraces, 5 primitive cultivars and 23 other germplasms along with five standard cultivars in a randomized complete block design with two replications during 2020–2021. Significant genetic variation was observed for ascorbic acid, chlorophyll content, calcium, magnesium, phosphorus, iron and zinc in fruits of bitter gourd. The landraces IC-68309 for ascorbic acid and zinc and IC-505640 for magnesium and three germplasm accessions IC-599434 for calcium, IC-85603A for phosphorous and IC-541435 for iron contents exhibited superior performance over the best standard cultivars. The Ward’s clustering for chlorophyll, ascorbic acid and mineral contents revealed the vast genetic diversity among germplasm accessions and accessions were ascertained into four different clusters. The germplasm accessions placed in Cluster IV were the most divergent based on nutritional parameters. Characterization for 25 InDels and 37 SSR markers resulted in the identification of 47 polymorphic loci and 161 alleles. Polymorphism information content and gene diversity were lowest for MC_g61ind0600 and highest for BG_gSSR_247 markers. Both phylogenetic analysis based on neighbor-joining and population structure produced two main groups and four subgroups. The highest mean nutritional value was observed in phylogenetic subgroup IV and Cluster IV. Principal component analysis for nutritional traits identified the five (IC-68309, IC-50524A, IC-85603A, IC-505640 and IC-541435) genotypes as excellent sources of minerals and ascorbic acid. These genetically and nutritionally diversified accessions identified from our research serve as elite genetic material for utilization in breeding programs to generate high-yielding nutritionally rich cultivars and to broaden the genetic base.