Debernardi Juan Manuel, Lin Huiqiong, Chuck George, Faris Justin D, Dubcovsky Jorge
Department of Plant Sciences, University of California, Davis, CA 95616, USA.
Plant Gene Expression Center, University of California, Berkeley, Albany, CA 94710, USA.
Development. 2017 Jun 1;144(11):1966-1975. doi: 10.1242/dev.146399. Epub 2017 Apr 28.
Wheat domestication from wild species involved mutations in the gene. The allele (wild wheats) is associated with elongated spikes and hulled grains, whereas the mutant allele (domesticated wheats) confers subcompact spikes and free-threshing grains. Previous studies showed that encodes an AP2-like transcription factor, but the causal polymorphism of the domestication traits remained unclear. Here, we show that the interaction between microRNA172 (miR172) and the allele is reduced by a single nucleotide polymorphism in the miRNA binding site. Inhibition of miR172 activity by a miRNA target mimic resulted in compact spikes and transition from glumes to florets in apical spikelets. By contrast, overexpression of miR172 was sufficient to induce elongated spikes and non-free-threshing grains, similar to those observed in three loss-of-function mutations. These lines showed transitions from florets to glumes in the basal spikelets. These localized homeotic changes were associated with opposing miR172/ gradients along the spike. We propose that the selection of a nucleotide change at the miR172 binding site of contributed to subcompact spikes and free-threshing grains during wheat domestication.
小麦从野生种驯化而来涉及该基因的突变。野生型等位基因（野生小麦）与细长的穗和带壳籽粒相关，而突变型等位基因（驯化小麦）则赋予紧密的穗和易脱粒的籽粒。先前的研究表明，该基因编码一种AP2类转录因子，但驯化性状的因果多态性仍不清楚。在这里，我们表明，miRNA172（miR172）与该等位基因之间的相互作用因miRNA结合位点的单核苷酸多态性而降低。通过miRNA靶标模拟物抑制miR172活性导致穗紧密，并使顶端小穗从颖片转变为小花。相比之下，miR172的过表达足以诱导出细长的穗和不易脱粒的籽粒，这与在三个该基因功能丧失突变体中观察到的情况相似。这些品系在基部小穗中表现出从小花到颖片的转变。这些局部的同源异型变化与沿穗轴相反的miR172/梯度相关。我们提出，在小麦驯化过程中，该基因miR172结合位点的核苷酸变化选择导致了紧密的穗和易脱粒的籽粒。
