Heritability and QTL for late-tiller formation in wheat (Triticum aestivum L.)
摘要
In wheat (Triticum aestivum L.) grown under irrigation or when rains become more frequent later in the growing season, late-developing tillers are a nuisance. In this paper, we hypothesised that late-tiller formation is under genetic control, and using data from a controlled environment, late-tiller formation was found to exhibit high heritability (h2 = 0.82). In the field environment, however, estimates of line mean heritability were lower, but the correlation between the glasshouse and field growth environment was high (r = 0.73; P value = 0.03). We explored the genomic regions controlling the variation by quantitative trait locus (QTL) analysis of data from a diversity panel and three bi-parent populations. Under controlled conditions, genome-wide analysis identified a single-nucleotide polymorphic (SNP) locus on chromosome 5A, IWA1, which mapped to a position approximately 1.1 Mb distal from vernalization gene, Vrn-A1. Twenty-four QTL were detected across three bi-parent populations, and when these were projected onto the sequenced genome of hexaploid wheat, the long arm of chromosome 5A was detected in all four populations. Allele effects at the Vrn-A1 locus showed that wheat genotypes carrying vrn-A1v allele had lower number of late tillers, compared to genotypes carrying the spring-type allele, Vrn-A1a. This was demonstrated in both the glasshouse and field environments, and hence, it was concluded that late tiller formation in wheat might be a pleiotropic effect of the flowering time genes. Knowledge of the genetic basis for late-tiller formation would allow agronomic research to focus on managing the risk by varietal selection.