Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3 OT Gatersleben, 06466, Seeland, Germany.
Department of Plant Sciences, University of California, Davis, USA.
Theor Appl Genet. 2019 Jun;132(6):1661-1676. doi: 10.1007/s00122-019-03305-4. Epub 2019 Feb 14.
Modifying morphometric inflorescence traits is important for increasing grain yield in wheat. Mapping revealed nine QTL, including new QTL and a new allele for the q locus, controlling wheat spike morphometric traits. To identify loci controlling spike morphometric traits, namely spike length (SL), internode length (IL), node number per spike (NPS), and node density (ND), we studied 146 Recombinant Inbred Lines of tetraploid wheat (Triticum turgidum L.) derived from standard spike and spike-branching mutant parents. Phenotypic analyses of spike morphometric traits showed low genetic coefficients of variation, resulting in high heritabilities. The phenotypic correlation between NPS with growing degree days (GDD) suggested the importance of GDD in the determination of node number in wheat. The major effect QTL for GDD or heading date was mapped to chromosome 7BS carrying the flowering time gene, Vrn3-B1. Mapping also identified nine QTL controlling spike morphometric traits. Most of these loci controlled more than a single trait, suggesting a close genetic interrelationship among spike morphometric traits. For example, this study identified a new QTL, QND.ipk-4AL, controlling ND (up to 17.6% of the phenotypic variance), IL (up to 11% of the phenotypic variance), and SL (up to 20.8% of the phenotypic variance). Similarly, the major effect QTL for IL was mapped to the q locus. Sequencing of the Q/q gene further revealed a new q allele, q-5A, in spike-branching accessions possessing a six base pair deletion close to the miR172 target site. The identification of q-5A suggested that the spike-branching tetraploid wheats are double mutants for the spikelet meristem (SM) identity gene, i.e., branched head (TtBH), and the q gene, which is believed to be involved in the SM indeterminacy complex in wheat.
修饰形态计量学花序性状对于提高小麦的籽粒产量很重要。图谱分析揭示了控制小麦穗形态计量学性状的 9 个 QTL，包括 q 位点的新 QTL 和新等位基因。为了鉴定控制穗形态计量学性状的基因座，即穗长（SL）、节间长度（IL）、穗上小穗数（NPS）和节点密度（ND），我们研究了 146 个来自四倍体小麦（Triticum turgidum L.）标准穗和穗分枝突变体亲本的重组自交系。穗形态计量学性状的表型分析显示，遗传系数变异较低，导致遗传力较高。NPS 与生长度日（GDD）之间的表型相关性表明 GDD 在决定小麦节点数方面的重要性。控制 GDD 或抽穗期的主效 QTL 被映射到携带开花时间基因 Vrn3-B1 的 7BS 染色体上。图谱分析还鉴定了控制穗形态计量学性状的 9 个 QTL。这些基因座中的大多数控制一个以上的性状，这表明穗形态计量学性状之间存在密切的遗传关系。例如，本研究鉴定了一个新的 QTL，QND.ipk-4AL，控制 ND（可达表型方差的 17.6%）、IL（可达表型方差的 11%）和 SL（可达表型方差的 20.8%）。同样，IL 的主效 QTL 被映射到 q 基因座上。q 基因的测序进一步揭示了一个新的 q 等位基因 q-5A，它存在于穗分枝材料中，其靠近 miR172 靶位点的六碱基对缺失。q-5A 的鉴定表明，穗分枝四倍体小麦是小穗分生组织（SM）身份基因，即分叉头（TtBH）和 q 基因的双突变体，后者被认为参与小麦 SM 不定性复合体。
