Mapping quantitative trait loci for growth responses to exogenously applied stress induced hormones in wheat

Abstract

Biotic and abiotic stresses are responsible for much of the variation in wheat production worldwide. The plant, in responding to stress events, increases the endogenous synthesis of hormones such as Abscisic Acid, Ethylene, Jasmonic Acid and Salicylic Acid. This paper was aimed at determining the location of plant-defence genes triggered by treatment with stress-induced hormones in a set of recombinant doubled haploid substitution lines involving variation for a single chromosome, 6A, previously shown to carry genes for aphid resistance. Eighty-three doubled haploid recombinant substitution (DHR) lines for chromosome 6A derived from the F1 of “Chinese Spring” (CS) × “Chinese Spring (Synthetic 6A)” (S6A) substitution line, were used as a mapping population. Plants of every genotype at the fully expanded 3rd leaf stage were subjected to four hormone treatments: ethylene (E), jasmonic acid (J), salicylic acid (S) and abscisic acid (A), together with an untreated control. The changes in a range of phenotypic traits were measured, aerial fresh weight (AFWC), aerial dry weight (ADWC), root fresh weight (RFWC), root dry weight (RDWC), foliar area (FAC). These were recorded twice: at the onset of the experiment before spraying with hormones and 72 h later. Nine QTLs were detected which were significantly associated with 6A molecular markers, explaining the variation for ADWC, RDWC and FAC. Most of the QTLs were associated with the interval between loci Xgwm459 and Xgwm334a, located in the telomeric region of the short arm of 6A. The dissection of complex agronomic traits such as tolerance to stress and QTLs related to exogenous hormone treatments could be used in marker-assisted selection for breeding wheat with tolerance to stresses.