Physiology of salt tolerance introgressions from Solanum galapagense in the domesticated tomato

Maria-Sole Bonarota ¹ Sean Fenstemaker ² Hans Vasquez-Gross ¹ Juli Petereit ¹ Patrícia C Ferreira dos Santos ¹ David M Francis ² Felipe H Barrios-Masias ^1*

• ¹ University of Nevada, Reno, Reno, United States
• ² The Ohio State University, Columbus, Ohio, United States

Wild trait introgression is a valuable breeding tool to increase tomato salinity tolerance, although it often results in deleterious linkage drag. This study aims to analyze the physiological and molecular mechanisms determining the salinity response of a tomato cultivar OH8245, Solanum galapagense accession LA1141, and two introgression lines derived from their crossing (ILs SG18_197 and SG18_247), which were previously screened for salt tolerance traits. The S. galapagense LA1141 had several salinity tolerance traits such as higher specific root length and root hydraulic conductivity, that maintained plant water status, along with better ion homeostasis and lower stomatal density than OH8245. On the other hand, OH8245 possessed traits that support increased biomass such as higher photosynthetic rate and relative growth rate than LA1141. LA1141 showed the lowest number of differentially expressed genes (706 DEGs) and OH8245 one of the highest (2524 DEGs), suggesting a constitutive set of genes that confer salinity tolerance or abiotic stress tolerance. LA1141 had 40 uniquely DEGs under salinity, of which nine and 16 were transferred to the ILs SG18_197 and SG18_247, respectively. Although salinity tolerance is a complex trait and has an energy cost to the plant, improved plant water potential, higher photosynthetic rate and lower sodium/potassium ratio were successfully transferred from LA1141 to at least one of the ILs. This study provides information to effectively support tomato breeding for salinity tolerance.