Characterization of a QTL on 7B for tiller number at the seedling stage in wheat landrace Yanda 1817

Effective tillers contribute to yield through adjusting plant population and affect 1000-kernel weight and kernel number per spike, which are favorable for wheat (Triticum aestivum L.) improvement. Wheat landraces show strong tillering ability and thus considerable potential for utilization in breeding. In this study, tiller number under nutrient solution condition was evaluated for 269 wheat recombinant inbred lines and their parents: the modern cultivar Beinong 6 and the landrace Yanda 1817, which exhibit strong tillering ability. A QTL, qTN-7B.1, significant in three independent experiments, was mapped between genetic marker Xgwm333 and 7ABD_wsnp_be518436B_Ta_2_1. The positive allele of qTN-7B.1 was from Yanda 1817, explained 10.21%-18.89% phenotypic variations. Pathway enrichment among tiller-bud transcriptome data for the two parents suggested that tillering ability was mainly associated with lignin biosynthesis and energy metabolism. Comparative genomic indicated that rice homologous gene TaMoc1-7B was located within qTN-7B.1 but was excluded for candidate since no high-impact sequence variations between parents and no transcript abundance during tiller bud development. Compared with published QTL for tiller suggested that qTN-7B.1 was most likely the novel. Further analysis the differentially gene expression analysis and variant through transcriptome data identified 33 nonsynonymous SNVs on 20 DEGs. In particular, TraesCS7B02G282100 encoded cinnamyl alcohol dehydrogenase crucially in lignin biosynthesis that the expression level of Beinong 6 exhibited 3.179-fold up-regulated and a synonymous SNP at conserved domain between parents, Therefore, TraesCS7B02G282100 was considered as candidate gene. Based on this SNP, a KASP marker was developed that anchored within qTN-7B.1 genetic region. This study laid the foundation for map-based cloning of qTN-7B.1 and provided genetic marker for plant architecture improvement through molecular breeding.

Automated summary

Effective tillers play a crucial role in wheat improvement by adjusting plant population, affecting 1000-kernel weight and kernel number per spike. This study identified a significant QTL, qTN-7B.1, for tillering ability in wheat, which explained a considerable proportion of phenotypic variations. Pathway enrichment analysis showed that lignin biosynthesis and energy metabolism were associated with tillering ability. A candidate gene, TraesCS7B02G282100, encoding cinnamyl alcohol dehydrogenase, was identified and a genetic marker within the qTN-7B.1 region was developed for plant architecture improvement.