QTL analyses for three grain quality traits in bread wheat using intervarietal mapping populations

Abstract

QTL analysis in bread wheat for three grain quality traits, namely grain protein content (GPC), pre-harvest sprouting tolerance (PHST) and grain weight (GW) has been conducted by us utilizing four intervarietal mapping populations, two each for GPC and PHST and one for GW. The approaches used included simple regression analysis (SMA), simple interval mapping (SIM), composite interval mapping (CIM), and an analysis involving detection of epistatic QTLs (E-QTLs) using QTLMapper. A large number of QTLs were detected in each case, and markers were developed which may prove useful in marker-assisted selection (MAS). An important result of this investigation is that for some quantitative traits like GPC, the major part of the genetic variation is due to E-QTLs and the Q * E interactions, and that the main effects contributed very little to the genetic variation. In contrast to GPC, PHST was controlled mainly by main effect QTLs and E-QTLs. For more detailed studies, one chromosome (3A) carrying a major QTL was selected for PHST and three chromosomes (1A, 2B, 7A) were selected for GW. A major, new, definitive and stable QTL (QPhs.ccsu-3A.1) for PHST that is independent of red-grain colour was detected on 3AL at a distance of ~183 cM from centromere. This QTL explained 24.68% to 35.21% variation in individual environments and 78.03% variation in pooled environment. For GW, one QTL each was identified on 1AS (QGw.ccsu-1A.1), 2BS (QGw.ccsu-2B.1) and 7AS (QGw.ccsu-7A.1). The variation explained by these individual QTLs in GW in different environments ranged from 9.0% to 19.85%. These studies should prove useful in QTL cloning and wheat improvement through marker aided selection (MAS).