Linking genetic determinants with salinity tolerance and ion relationships in eggplant, tomato and pepper

Authors: Suarez, Donald; Marquez Celis, Nydia; Ferreira, Jorge; REYNOLDS, TREVOR - University Of California; Sandhu, Devinder

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2021
Publication Date: 8/11/2021
Citation: Suarez, D.L., Celis, N., Ferreira, J.F.S., Reynolds, T., Sandhu, D. 2021. Linking genetic determinants with salinity tolerance and ion relationships in eggplant, tomato and pepper. Scientific Reports. 11. Article 16298. https://doi.org/10.1038/s41598-021-95506-5.
DOI: https://doi.org/10.1038/s41598-021-95506-5

Interpretive Summary: Plants in the Solanaceae family such as tomato, eggplant, and pepper are important vegetable crops that are extensively cultivated in arid and semi-arid regions and are known to be relatively sensitive to salinity. These regions face increasing scarcity of fresh water hence growers are turning to more saline groundwaters and wastewaters. To improve salt tolerance, one strategy is to evaluate different cultivars for salt tolerance and examine physiological, ion composition, and gene expression parameters that may relate to salt tolerance. We measured fruit yield of 24 cultivars of tomato, eggplant, and pepper under control and saline conditions and ranked plants in terms of relative yield (salt tolerance). We measured ion composition of plant parts and physiological parameters and selected a more- and less-salt tolerant cultivar for each of the species for gene expression analyses of 12 genes associated with plant salt tolerance. Relative yield under salt treatment varied from 56 to 84 % for tomato, from 52 to 114% for eggplant, and from 52 to 99% for pepper. Differences in cultivar relative yield were related to several factors (ability to maintain K accumulation under salt stress, ability to exclude Na, and ability to restrict Na transport to leaves) and were consistent with expression of relevant genes. This information is of direct use to growers selecting suitable cultivars as well as for plant geneticists seeking to develop new more salt tolerant cultivars of these species.

Technical Abstract: The Solanaceae family includes commercially important vegetable crops characterized by their relative sensitivity to salinity. Evaluation of 8 eggplant (Solanum melongena), 7 tomato (Solanum lycopersicum), and 8 pepper (Capsicum spp.) heirloom cultivars from different geographic regions 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, 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 leaf 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 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 and will enable breeders to increase the salt tolerance of Solanaceae cultivars.