Genome-wide QTL analysis for pre-harvest sprouting tolerance in bread wheat

Abstract

A framework linkage map comprising 214 molecular marker (SSR, AFLP, SAMPL) loci was prepared using an intervarietal recombinant inbred line (RIL) mapping population of bread wheat. The RIL population that was developed from the cross SPR8198 (red-grained and PHS tolerant genotype) 9 HD2329 (white-grained and PHS susceptible genotype) following single seed descent segregated for pre-harvest sprouting (PHS). The RIL population and parental genotypes were evaluated in six different environments and the data on PHS were collected. Using the linkage map and PHS data, genome-wide single-locus and two-locus QTL analyses were conducted for PHS tolerance (PHST). Single-locus analysis following composite interval mapping (CIM) detected a total of seven QTL, located on specific arms of five different chromosome (1AS, 2AL, 2DL, 3AL and 3BL). These seven QTL included two major QTL one each on 2AL and 3AL. Two of these seven QTL were also detected following two-locus analysis, which resolved a total of four main-effect QTL (M-QTL), and 12 epistatic QTL (E-QTL), the latter involved in 7 QTL 9 QTL interactions. Interestingly, none of these M-QTL and E-QTL detected by two-locus analysis was involved in Q 9 E and Q 9 Q 9 E interactions, supporting the results of ANOVA, where genotype 9 environment interaction were non-significant. The QTL for PHS detected in the present study may be efficiently utilized for marker-aided selection for enhancing PHST in bread wheat.

Maximizing the identification of QTL for pre-harvest sprouting resistance using seed dormancy measures in a white-grained hexaploid wheat population

“…The continuous normal and skewed distributions of the population indicated that multiple minor alleles are involved in controlling seed dormancy. This complex genetic control of dormancy is consistent with earlier studies Kulwal et al 2004;Imtiaz et al 2008;Mohan et al 2009;Fofana et al 2009). The f Positive sign in germination resistance (GR) and negative sign in germination index (GI) and in percent germination (PG) indicated that SC8021-V2 allele contributed resistance for respective trait measure-duration relative to the AC Karma allele (values given in range for respective trait measure with multiple durations) g QTL designation (favourable parental allele) different durations of germination maximized differential under some conditions, revealing a bimodal distribution that indicated, in addition to minor genes, the presence of a major gene.…”

“…QTL, QPhs.spa-2A, for GI7d from the GH environment was in interval gwm294-cfa2058 on chromosome 2A, a different position from the previous reports (Mohan et al 2009;Kumar et al 2009;Kobayashi et al 2010;Jaiswal et al 2012;Knox et al 2012). The marker coverage was low on chromosome 2A which may affect the QTL position and this conclusion.…”

“…Lohwasser et al (2013) also reported dormancy QTL QD20.ipk-1D on chromosome 1D just 2.2 cM from QPhs.spa-1D. The minor effect QPhs.spa-1A1 QTL at cfa2135 coincides with a QTL reported by Knox et al (2012) and Jaiswal et al (2012), and is near to QTL reported in many other studies (Glein et al 2006;Munkvold et al 2009;Mohan et al 2009;Singh et al 2010;Rehman et al 2012;Singh et al 2014). Singh et al (2010) and Zanetti et al (2000) detected a QTL on chromosome 1A that was possibly involved with alpha-amylase activity, an important predictor of preharvest sprouting.…”

“…The QPhs.spa-7A2 QTL strongly identified in the field environment and mapped to the short arm of chromosome 7A at interval wmc17-barc154 which is in a similar region as QPhsd.spa-7A reported by Knox et al (2012) and QPhs.spa-7A reported by Singh et al (2014) in durum wheat, and QPhs.ccsu-7A.1 reported by Mohan et al (2009) in hexaploid wheat. This consistency suggests the 7A QTL is important for imparting pre-harvest sprouting resistance in different genetic backgrounds.…”

“…The genetic control of pre-harvest sprouting resistance is complex, factors responsible for resistance are dispersed on almost every wheat chromosome and complex interactions occur between QTL (Q 9 Q) and/or among environments (Q 9 Q 9 E) (Kulwal et al 2004;Imtiaz et al 2008;Kumar et al 2009;Mohan et al 2009). Also, the effects of QTL range from minor to major corresponding to a range in phenotypic expression from susceptible to resistant.…”