Location: Crop Improvement and Protection Research
Project Number: 2038-21530-002-12-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Oct 1, 2016
End Date: Mar 31, 2019
Global warming has led to higher sea levels and farther saltwater intrusion beyond the city limits of Castroville and Salinas, California, and promotes water transpiration from plants and evaporation from soil, leaving more salts behind in soil. Central and Imperial Valleys face increasing salinity problems due to high salt levels in irrigation water, a shallow water table, and inadequate drainage. There is a pressing need for salt-tolerant varieties to mitigate the salinity stresses on, and improve sustainability of, lettuce production in California. The project aims to identify physiological traits, proteins and genes that underlie salt-tolerance in lettuce and incorporate them into commercial cultivars protecting yield and production. The project will help develop lettuce cultivars with increased salt tolerance, reduce water quality requirement and costs, and mitigate the effects of saline water, and therefore improve sustainability of lettuce production in California.
In the first year, lettuce physiological traits associated with salinity tolerance will be identified utilizing both greenhouse and growth chamber salt stress experiments, by comparing physiological responses in salt tolerant and susceptible genotypes. In the first and second year the protein response pattern to salt stress in salt tolerant and susceptible genotypes will be analyzed and compared using two-dimensional gel electrophoresis, and critical proteins involved in salt tolerance will be identified by mass spectrometry. Also in the second year the expression patterns of known salt-responsive genes will be analyzed using quantitative real-time polymerase chain reaction while simultaneously utilizing the lettuce genome to identify novel salt-responsive genes. The integrated analyses of physiological traits, proteins and genes will allow identification of critical factors in salt tolerance, which could be used to develop molecular markers to help create tolerant germplasms. Breeding to incorporate salt tolerance factors will begin immediately upon the start of the project. Salt-tolerant lettuce varieties identified in the previous project will be crossed to each other to further increase the level of tolerance, and the progenies of the crosses will be planted under salinity conditions. Salt-tolerant plants of different lettuce types will be selected and transplanted into pots to produce seeds in a greenhouse for next round of selection. Salt-tolerant breeding lines/cultivars developed will be evaluated in the field in Salinas, Central, and Imperial Valleys under salt-stress conditions to demonstrate results to producers and seed companies, which can incorporate these salt-tolerant trait containing lines into existing breeding programs to produce cultivars for commercial production by growers. Field trial results from multiple locations will be analyzed statistically to identify best-performing lines for public release.