Identification and validation of a major chromosome region for high grain number per spike under meiotic stage water stress in wheat (Triticum aestivum L.)

Abstract

Grain number is a major trait for wheat yield under dryland farming. An International Triticeae Mapping Initiative (ITMI) mapping population comprising 105 recombinant inbred lines (RIL) developed from a cross between a Synthetic hexaploid wheat (Triticum aestivum) ‘W7984’ and a spring wheat variety ‘Opata M85’ was used to identify quantitative trait loci (QTL) associated with grain number per spike under two treatment conditions, normal watering and water stress during meiosis. Two major QTL for grain number per spike on the main stem Q.Gnu.uwa-5A-1 and Q.Gnu.uwa-5A-2 with phenotypic variations of 25.71% and 24.93%, respectively, were detected on the long arm of chromosome 5A when plants were exposed to water stress during meiosis. One QTL (Q.Gnu.uwa-2A) with a LOD score of 2.8 was detected on the long arm of chromosome 2A under normal watering condition. The alleles associated with higher grain number per spike under different treatment conditions came from the Synthetic W7984 parent. Two populations developed from crosses Synthetic W7984 × Lang and Synthetic W7984 × Westonia were used to validate the identified QTL under water stress during meiosis. SSR markers Xbarc230 and Xbarc319 linked with the identified QTL on chromosome 5AL were validated in the two F2:4 segregating populations. These closely linked SSR markers could potentially be utilized in marker-assisted selection to reduce yield loss in regions where water stress during meiosis occurs frequently. The identified QTL can be incorporated into elite lines / cultivars to improve wheat grain yield.

Determining the Genetic Architecture of Reproductive Stage Drought Tolerance in Wheat Using a Correlated Trait and Correlated Marker Effect Model

“…The vernalization gene VRN-A1 on chromosome 5A is an important wheat adaptability trait with pleiotropic effects on grain yield (Snape et al 1985). VRN-A1 frequently co-localises with QTL for abiotic stress “tolerance” and ABA accumulation when selection is based on grain number (Snape et al 1985; Quarrie et al 1994; Bálint et al 2009; Pinto et al 2010; Iehisa et al 2014; Wang et al 2016; Onyemaobi et al 2018). We therefore designed a QTL mapping approach aimed at identifying drought tolerance loci (that is, capacity to maintain spike grain number) rather than grain yield QTL.…”

QTL Mapping Using a High-Density Genetic Map to Identify Candidate Genes Associated With Metribuzin Tolerance in Hexaploid Wheat (Triticum aestivum L.)

“…Analysis of variance (ANOVA) was performed based on the fixed effects model of Y ij = μ + g j + Ɛ ij , where Y ij is the observed phenotypic mean, μ is the population mean, g j is the effect due to the j th genotype, and Ɛ ij is the random error. Heritability was measured using the formula of , where and are estimated genotypic and error variances as and , respectively, where MSg is the mean square of the RILs, MSe is the residual error, and r is the number of replicates ( Nyquist and Baker, 1991 ; Onyemaobi et al., 2018 ).…”

“…e are estimated genotypic and error variances as d 2 g = MSg−MSe r and d 2 e = MSe r , respectively, where MSg is the mean square of the RILs, MSe is the residual error, and r is the number of replicates (Nyquist and Baker, 1991;Onyemaobi et al, 2018).…”

Natural Variation in Ovule Morphology Is Influenced by Multiple Tissues and Impacts Downstream Grain Development in Barley (Hordeum vulgare L.)

“…The number of mature florets has been linked to barley yield (Alqudah and Schnurbusch, 2014), while the size and number of cells within the pistil has been linked to spike dry weight in wheat (Guo et al, 2015; Guo et al, 2016). Heat and drought stress have been shown to compromise aspects of pistil and ovule maturation, leading to defects in fertilization and grain development in wheat ( Triticum aestivum ) and maize ( Zea mays ; (Saini et al, 1983;Jäger et al, 2008; Oury et al, 2016; Onyemaobi et al, 2018). Thus, correct development of the female reproductive organs is an important determinant of floral fertility and yield, especially under conditions of environmental stress.…”