Würschum Tobias, Jähne Felix, Phillips Andrew L, Langer Simon M, Longin C Friedrich H, Tucker Matthew R, Leiser Willmar L
State Plant Breeding Institute, University of Hohenheim, Stuttgart, Germany.
Rothamsted Research, Harpenden, UK.
J Exp Bot. 2020 Jun 22;71(12):3428-3436. doi: 10.1093/jxb/eraa106.
Awns are bristle-like structures formed at the tip of the lemma on the florets of some cereal grasses. Wild-type wheat is awned, but awnletted and awnless variants have been selected and nowadays all forms are cultivated. In this study, we dissected the genetic control underlying variation of this characteristic feature by association mapping in a large panel of 1110 winter wheat cultivars of worldwide origin. We identified the B1 (Tipped 1) locus on chromosome 5A as the major determinant of awnlessness globally. Using a combination of fine-mapping and expression analysis, we identified a putative C2H2 zinc finger protein with an EAR domain, characteristic of transcriptional repressors, as a likely candidate for Tipped 1. This gene was found to be up-regulated in awnless B1 compared with awned b1 plants, indicating that misexpression of this transcriptional regulator may contribute to the reduction of awn length in B1 plants. Taken together, our study provides an entry point towards a better molecular understanding of the evolution of morphological features in cereals through selection and breeding.
芒是一些禾本科谷物小花外稃顶端形成的刚毛状结构。野生型小麦有芒，但已选育出了无芒和短芒变种，如今所有类型都有种植。在本研究中，我们通过对来自世界各地的1110个冬小麦品种的大型群体进行关联分析，剖析了这一特征变异背后的遗传控制。我们确定5A染色体上的B1（Tipped 1）位点是全球范围内无芒的主要决定因素。通过精细定位和表达分析相结合，我们鉴定出一种具有EAR结构域的假定C2H2锌指蛋白，这是转录抑制因子的特征，它可能是Tipped 1的候选基因。与有芒的b1植株相比，该基因在无芒的B1植株中上调，表明这种转录调节因子的错误表达可能导致B1植株芒长度的缩短。综上所述，我们的研究为通过选择和育种更好地从分子层面理解谷物形态特征的进化提供了切入点。
