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Genetic insights into morphometric inflorescence traits of wheat
Gizaw M. Wolde, Corinna Trautewig, Martin Mascher, Thorsten Schnurbusch
Theoretical and Applied Genetics, June 2019, Volume 132, Issue 6, pp 1661–1676
Abstract
Key message
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.
Abstract
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, qdel-5A, in spike-branching accessions possessing a six base pair deletion close to the miR172 target site. The identification of qdel-5A suggested that the spike-branching tetraploid wheats are double mutants for the spikelet meristem (SM) identity gene, i.e., branched headt (TtBHt), and the q gene, which is believed to be involved in the SM indeterminacy complex in wheat.
Fig. 2
Genetic maps of chromosomes showing QTL for spike length (SL), node number per spike (NPS), node density (ND), heading date (HD), and internode length (IL). Effect of the QTL is shown as box plots computed after grouping the RILs into two sets based on the closest marker flanking each QTL. Grouping was made based on the closest marker for each QTL (shown below the box plot). (+) shows the phenotype of the RILs carrying the QTL, and (−) shows the phenotype of the RILs without the QTL. B, allele from Bellaroi; T, allele from TRI 19165. ‘Miracle Wheat’ allele or the bht-A1 allele on chromosome 2A (39.1 cM) is underlined. Pink dash shows the putative centromeric position per chromosome
