Puneet Kaur Mangat, Junghyun Shim, Ritchel B. Gannaban, Joshua J. Singleton & Rosalyn B. Angeles-Shim

Theoretical and Applied Genetics April 2021; vol. 134: 1133–1146.

Key message

Alien introgressions that were captured in the genome of diploid plants segregating from progenies of monosomic alien addition lines of S. lycopersicoides confer novel phenotypes with commercial and agronomic value in tomato breeding.

Abstract

Solanum lycopersicoides is a wild relative of tomato with a natural adaptation to a wide array of biotic and abiotic challenges. In this study, we identified and characterized diploid plants segregating from the progenies of monosomic alien addition lines (MAALs) of S. lycopersicoides to establish their potential as donors in breeding for target trait improvement in tomato. Molecular genotyping identified 28 of 38 MAAL progenies having the complete chromosome complement of the cultivated tomato parent and limited chromosome introgressions from the wild S. lycopersicoides parent. Analysis of SSR and indel marker profiles identified 34 unique alien introgressions in the 28 MAAL-derived introgression lines (MDILs) in the genetic 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 the MDILs that are lacking in the cultivated parent or the source MAALs indicates the capture of novel genetic variation by the diploid introgression lines that can add commercial and agronomic value to tomato. In particular, screening of representative MDILs for drought tolerance at the vegetative stage identified MDIL 2 and MDIL 11III as drought tolerant based on visual scoring. A regulated increase in stomatal conductance of MDIL 2 under drought stress indicates better water use efficiency that allowed it to survive for 7 days under 0% moisture level.

See: https://link.springer.com/article/10.1007/s00122-020-03758-y

Figure 1: Graphical genotype of MDILs representing 19 distinct combinations of chromosome segment introgressions from S. lycopersicoides. Black and gray bars represent homozygous introgressions from S. lycopersicoides and heterozygous introgression from both parents, respectively. Striped and dotted bars represent homozygous and heterozygous, non-parental introgressions, respectively. Red dots indicate the 34 unique wild introgressions detected across all the identified MDILs that segregated from the MAALs. Representative, polymorphic markers used to genotype the MDILs are illustrated. Numbers following the marker name indicate the physical position (Mb) of the markers in the chromosome