Fine mapping of QTL for water use efficiency‐related traits on chromosome 9 of Solanum habrochaites in the field

Abstract

Fresh water is increasingly limited due to climate change. One way to reduce fresh water use by irrigated agriculture is to breed plants that can produce adequate yields with less water. A wild tomato, Solanum habrochaites, is more water stress tolerant than cultivated tomato, S. lycopersicum L. Our study aimed to fine map quantitative trait loci (QTL) for maturity, yield, and water use efficiency (WUE)-related traits (shoot dry weight and carbon isotope discrimination, ∆ 13 C) on chromosome 9 in S. habrochaites using a set of 21 sub-near isogenic lines (sub-NILs). These sub-NILs and controls were evaluated in field experiments grown under full and reduced irrigation treatments across 2 yr. Genotype × environment interactions were significant, so the data was separated into subsets of environments for further analyses. Significant QTL were detected for 20 trait-environment combinations. All QTL were partially or completely coincident. The presence of the S. habrochaites allele at QTL was associated with later maturity, lower yields, and greater WUE. However, yield and ∆ 13 C exhibited no or low correlations with each other, suggesting these traits could be selected for improvement independently during breeding. Two of 21 sub-NILs showed superior performance for WUE and yield compared to controls. These two genotypes may prove useful in breeding programs to improve the WUE of tomato cultivars without negative effects on yield. INTRODUCTIONFresh water is a limited resource in many parts of the world, such as the arid western United States that includes Abbreviations: ∆ 13 C, carbon isotope discrimination; DAPG, days after planting to first green fruit; DAPR, days after planting to first ripe fruit; ET c , crop evapotranspiration rate; ET o , reference evapotranspiration rate; GxE, genotype × environment interaction; LOD, logarithm of odds; NIL, near isogenic line; QTL, quantitative trait locus/loci; QTLxE, quantitative trait locus × environment interactions; RYLD, ripe fruit yield; SDW, shoot dry weight; SNP, single nucleotide polymorphism; sub-NIL, sub-near isogenic line; TYLD, total fruit yield; WUE, water use efficiency; δ 13 C, carbon isotopic composition.

Bin mapping of water stress tolerance‐related, fruit quality, and horticultural traits in tomato introgression lines derived from wild Solanum habrochaites

“…Other traits used to indirectly measure water stress tolerance that are negatively correlated with water stress tolerance include carbon isotope discrimination and dry biomass (Richards, 2006; Tuberosa, 2012). These various indirect measurements have been used in a wide variety of crops including corn (Payero et al., 2009; Richards, 2006; Tuberosa, 2012), tomato (Groh et al., 2022; Lounsbery et al., 2016), wheat (Richards, 2006; Tuberosa, 2012), sorghum (Richards, 2006), and soybean (Richards, 2006; Tuberosa, 2012). Previous studies of water stress tolerance in tomato have employed yield, shoot biomass, specific leaf area, and carbon isotope discrimination as indirect measurements (Groh et al., 2022; Lounsbery et al., 2016).…”