Prioritisation of candidate genes in QTL regions for seed germination and early seedling growth in bread wheat (Triticum aestivum) under salt-stress conditions

Abstract

Salinity and drought are major abiotic stresses affecting wheat (Triticum aestivum L.) production throughout the world, and discovery of loci for traits affecting yield under salinity may lead to the breeding for salt-tolerant plants. In the present study, 186 F10 recombinant inbred line (RIL) populations were evaluated under salt-stress conditions in order to identify main-effect and epistatic-effect quantitative trait loci (QTLs) for 15 traits in wheat during the germination and early-seedling stages. In total, 61 main-effect QTLs on 15 chromosomes and 21 epistatic interactions on 12 chromosomes were detected through composite interval mapping (CIM) and a mixed-model-based CIM method. Two major QTLs for primary-leaf fresh weight and coleoptile fresh weight were detected on chromosome (or linkage group) 5B2 and 2D, respectively, which contributed ~44% and 43% of the phenotypic variance. Additionally, 12 QTL clusters including different traits were detected on 1A1, 3A, 4A, 2B1, 3B, 5B1 and 2D1. Candidate genes were identified within QTL regions and gene ontology (GO) enrichment analysis was performed. In total, 9134 candidate genes were grouped into 274 GO terms (including 79 GO terms involved in the ‘biological process’ category). These genes directly or indirectly play a vital role such as lipid localisation, biological regulation, fatty acid biosynthetic process, cellular process, DNA conformation change, translational elongation, carbohydrate metabolic process, Fe ion homeostasis, hydrogen peroxide metabolic process, and pigment biosynthetic process at the germination and early-seedling stages under salt-stress conditions.