QTLs for potato tuber resistance toDickeya solaniare located on chromosomes II and IV

Abstract

Soft rot is a bacterial disease that causes heavy losses in potato production worldwide. The goal of this study was to identify quantitative trait loci (QTLs) for potato tuber resistance to bacterium Dickeya solani and for tuber starch content to study the relationship between these traits. A highly resistant diploid hybrid of potato was crossed with a susceptible hybrid to generate the F1 mapping population. Tubers that were wound-inoculated with bacteria were evaluated for disease severity expressed as the mean weight of rotted tubers, and disease incidence measured as the proportion of rotten tubers. Diversity array technology (DArTseq) was used for genetic map construction and QTLs analysis. The most prominent QTLs for disease severity and incidence were identified in overlapping regions on potato chromosome IV and explained 22.4% and 22.9% of the phenotypic variance, respectively. The second QTL for disease severity was mapped to chromosome II and explained 16.5% of the variance. QTLs for starch content were detected on chromosomes III, V, VI, VII, VIII, IX, XI, and XII in regions different than the QTLs for soft rot resistance. Two strong and reproducible QTLs for resistance to Dickeya solani on potato chromosomes IV and II might be useful for further study of candidate genes and marker development in potato breeding programs. The relationship between tuber resistance to bacteria and the starch content in potato tubers was not confirmed by QTL mapping, which makes the selection of genotypes highly resistant to soft rot with a desirable starch content feasible.

Plant necrotrophic bacterial disease resistance phenotypes, QTL, and metabolites identified through integrated genetic mapping and metabolomics in Solanum species

“…For necrotrophic bacteria, wild species do exhibit some variation in quantitative measures of resistance and the germplasm tends to be highly heterozygous (McCauley, 2021;Lebecka et al, 2021b). Subsequent genetic mapping within wild potato species shows that many necrotrophic bacterial resistance traits are quantitative (Jansky et al, 2014;Chung et al, 2017;Lebecka et al, 2021a;Ma et al, 2022), showing that bacterial disease resistance can be improved via introgression breeding. Currently, the potato industry is experiencing a revolutionary shift in breeding towards diploid genetics, and double monoploid lines (DM) are being used for research (Xu et al, 2011;Jansky et al, 2016;Bethke et al, 2022).…”

“…While these genetic mapping populations tend to be small due to poor tuberization and fruit formation attributed to the mixing of very diverse genetics (i.e., wild x domesticated species crosses), they can still be studied to understand the distribution of resistance traits, their qualitative or quantitative nature, and to begin to understand the integrative relationship of Solanum genes, metabolites, and resistance traits. Some studies have performed quantitative trait loci (QTL) analysis of DM x wild diploid Solanum populations and identified soft rot resistance across multiple chromosomes (Zimnoch-Guzowska et al, 2000;Lebecka et al, 2021a), although the links between these QTL and biochemical resistance traits such as with S. chacoense are unknown.…”