Quantitative Trait Loci for Water-Stress Tolerance Traits Localize on Chromosome 9 of Wild Tomato

A wild tomato species (Solanum habrochaites S. Knapp & D.M. Spooner) is tolerant to many abiotic stresses, including limited water, and can serve as a valuable genetic resource for breeding cultivated tomato (S. lycopersicum L.). Previously, we developed and used a set of 18 sub-near-isogenic lines (sub-NILs) containing introgressions from chromosome 9 of S. hab- rochaites to determine the genetic basis of tol- erance to rapid-onset water stress imposed by root chilling. In this study, we used this same set of 18 sub-NILs to investigate the genetic basis of tolerance to slow-onset water stress in the field imposed by restricted irrigation (with full water treatment as control) in replicated experiments for 2 yr in Davis, CA. The sub-NILs were evalu- ated for C isotope discrimination (D 13 C), specific leaf area (SLA), shoot dry weight (SDW), yield, and other horticultural traits. A total of 19 QTL for D 13 C, SLA, SDW, yield, and maturity traits were