Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr 3, 06466, Stadt Seeland OT Gatersleben, Germany.
European Wheat Breeding Center, BASF Agricultural Solutions GmbH, Am Schwabeplan 8, 06466, Stadt Seeland OT Gatersleben, Germany.
Sci Rep. 2021 Jan 15;11(1):1585. doi: 10.1038/s41598-020-80473-0.
Total spikelet number per spike (TSN) is a major component of spike architecture in wheat (Triticum aestivum L.). A major and consistent quantitative trait locus (QTL) was discovered for TSN in a doubled haploid spring wheat population grown in the field over 4 years. The QTL on chromosome 7B explained up to 20.5% of phenotypic variance. In its physical interval (7B: 6.37-21.67 Mb), the gene FLOWERING LOCUS T (FT-B1) emerged as candidate for the observed effect. In one of the parental lines, FT-B1 carried a non-synonymous substitution on position 19 of the coding sequence. This mutation modifying an aspartic acid (D) into a histidine (H) occurred in a highly conserved position. The mutation was observed with a frequency of ca. 68% in a set of 135 hexaploid wheat varieties and landraces, while it was not found in other plant species. FT-B1 only showed a minor effect on heading and flowering time (FT) which were dominated by a major QTL on chromosome 5A caused by segregation of the vernalization gene VRN-A1. Individuals carrying the FT-B1 allele with amino acid histidine had, on average, a higher number of spikelets (15.1) than individuals with the aspartic acid allele (14.3) independent of their VRN-A1 allele. We show that the effect of TSN is not mainly related to flowering time; however, the duration of pre-anthesis phases may play a major role.
小穗总数每穗（TSN）是小麦（Triticum aestivum L.）穗结构的主要组成部分。在一个经过 4 年田间种植的双单倍体春小麦群体中，发现了一个与 TSN 相关的主要且一致的数量性状位点（QTL）。该 QTL 位于 7B 染色体上，可解释表型变异的 20.5%。在其物理区间（7B：6.37-21.67 Mb）内，开花时间基因 FLOWERING LOCUS T（FT-B1）成为观察到的效应的候选基因。在一个亲本系中，FT-B1 在编码序列的第 19 位发生了非同义突变。该突变将天冬氨酸（D）突变为组氨酸（H），发生在高度保守的位置。该突变在一个包含 135 个六倍体小麦品种和地方品种的群体中出现频率约为 68%，而在其他植物物种中未发现。FT-B1 对抽穗期和开花时间（FT）的影响较小，主要由 5A 染色体上的一个主效 QTL 引起，该 QTL 由 vernalization 基因 VRN-A1 的分离引起。携带天冬氨酸氨基酸等位基因的个体的小穗数（15.1）平均高于携带组氨酸氨基酸等位基因的个体（14.3），而与他们的 VRN-A1 等位基因无关。我们表明，TSN 的效应主要与开花时间无关；然而，开花前阶段的持续时间可能起主要作用。
