Alien introgression and morpho-agronomic characterization of diploid progenies of Solanum lycopersicoides monosomic alien addition lines (MAALs) toward pre-breeding applications in tomato (S. lycopersicum)

Solanum lycopersicoides is a wild relative of tomato with a natural adaptation to a wide array of biotic and abioticchallenges. In this study, we identified and characterized diploid plants segregating from the progenies of monosomic alienaddition lines (MAALs) of S. lycopersicoides to establish their potential as donors in breeding for target trait improvementin tomato. Molecular genotyping identified 28 of 38 MAAL progenies having the complete chromosome complement of thecultivated tomato parent and limited chromosome introgressions from the wild S. lycopersicoides parent. Analysis of SSR andindel marker profiles identified 34 unique alien introgressions in the 28 MAAL-derived introgression lines (MDILs) in thegenetic background of tomato. Conserved patterns of alien introgressions were detected among sibs of MDILs 2, 3, 4 and 8.Across MDILs, a degree of preferential transmission of specific chromosome segments was also observed. Morphologically,the MDILs closely resembled the cultivated tomato more than S. lycopersicoides. The appearance of novel phenotypes in theMDILs that are lacking in the cultivated parent or the source MAALs indicates the capture of novel genetic variation by thediploid introgression lines that can add commercial and agronomic value to tomato. In particular, screening of representativeMDILs for drought tolerance at the vegetative stage identified MDIL 2 and MDIL 11III as drought tolerant based on visualscoring. A regulated increase in stomatal conductance of MDIL 2 under drought stress indicates better water use efficiencythat allowed it to survive for 7 days under 0% moisture level.