Linking Genetic Determinants With Salinity Tolerance and Ion Relationships in Eggplant, Tomato, and Pepper

Abstract

The Solanaceae family includes commercially important vegetable crops characterized by their relative sensitivity to salinity. Evaluation of 24 heirloom cultivars of eggplant (Solanum melongena), tomato (Solanum lycopersicum), and pepper (Capsicum spp.) from different geographic regions under salinity revealed significant variation in salt tolerance. Relative fruit yield under salt treatment varied from 52 to 114% for eggplant, 56 to 84% for tomato, and 52 to 99% for pepper. Cultivars from all three crops, except Habanero peppers (C. chinense), restricted Na transport from roots to shoots under salinity. The high salt tolerance level showed a strong association with low leaf Na concentration. Additionally, the K-salinity/K-control ratio was critical in determining the salinity tolerance of a genotype. Differences in relative yield under salinity were regulated by several component traits, which was consistent with the gene expression of relevant genes. Gene expression analyses using 12 genes associated with plant salt tolerance showed that, for eggplant and pepper, Na+ exclusion was a vital component trait, while sequestration of Na+ into vacuoles was critical for tomato plants. The high variability for salt tolerance found in heirloom cultivars helped characterize genotypes based on component traits of salt tolerance, enabling breeders to increase the salt tolerance of Solanaceae cultivars.