Viral infection by CABMV-cowpea aphid-borne mosaic virus- reduces gas exchange in passion fruit leaves

Passion fruit (Passiflora spp.) is an important crop with increasing yields in recent years. However, its expansion in Brazil faces challenges, including diseases affecting the crop. The main disease is passion fruit woodiness, caused by cowpea aphid-borne mosaic virus (CABMV), which leads to leaf and fruit symptoms, compromising both quality and production. Viral infections directly affect plant physiology and often disrupt gas exchange by impacting leaf function. In this study, our aim was to analyze gas exchange caused by CABMV and to estimate genetic parameters to aid in the selection of genotypes with superior physiological performance. Gas exchange measurements were performed on passion fruit leaves from full-sib families showing varying symptoms of infection, as well as on leaves from resistant (P. setacea) and susceptible (P. edulis) individuals. Disease severity was assessed on a rating scale associated with the SPAD index. The estimation of genetic parameters facilitated the determination of variances, heritability and accuracy for each physiological variable examined. Our results confirmed that the presence of CABMV in leaves reduces photosynthetic rates and stomatal conductance, especially in the face of moderate and severe symptoms. Furthermore, genotypic variation played a more significant role in the photosynthetic rate, intercellular CO2 concentration and transpiration rate compared to phenotypic variation. Heritability values ranged from moderate to high, and accuracy values were high, validating the reliability of the analyses. In conclusion, the study demonstrates, for the first time, the negative impact of CABMV infection on gas exchange in passion fruit leaves. In addition, it highlights the potential use of physiological variables, such as photosynthesis, in the selection of individuals with superior physiological performance in passion fruit breeding programs.