microRNA172 plays a crucial role in wheat spike morphogenesis and grain threshability.
microRNA172 plays a crucial role in wheat spike morphogenesis and grain threshability.
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DOI：
10.1242/dev.146399
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发表时间：
2017-06-01
期刊：
影响因子：
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通讯作者：
Dubcovsky J
中科院分区：
文献类型：
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作者：
Debernardi JM;Lin H;Chuck G;Faris JD;Dubcovsky J
小麦从野生种驯化涉及到Q基因的突变。q等位基因（野生小麦）与长穗和脱壳粒有关，而突变q等位基因（驯化小麦）赋予亚紧凑的穗和自由脱粒的籽粒。以往的研究表明，Q编码ap2样转录因子，但驯化性状的因果多态性尚不清楚。在这里，我们发现microRNA172 （miR172）和Q等位基因之间的相互作用由于miRNA结合位点的单核苷酸多态性而减少。miRNA靶模拟物对miR172活性的抑制导致了顶端小穗的紧密化和从颖片到小花的转变。相比之下，miR172的过表达足以诱导长穗和非自由脱粒，类似于在三个Q功能丧失突变中观察到的结果。这些谱显示了基部小穗从小花到颖片的转变。这些局部同源性变化与沿尖刺方向相反的miR172/Q梯度有关。我们认为，在小麦驯化过程中，Q的miR172结合位点的一个核苷酸变化的选择促成了亚紧凑的穗和自由脱粒。AP2基因Q的microRNA172结合位点的核苷酸变化在小麦驯化和现代自由脱粒小麦的起源中发挥了关键作用。参见本期Greenwood等人的文章。
Wheat domestication from wild species involved mutations in the Q gene. The q allele (wild wheats) is associated with elongated spikes and hulled grains, whereas the mutant Q allele (domesticated wheats) confers subcompact spikes and free-threshing grains. Previous studies showed that Q 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 Q 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 Q 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/Q gradients along the spike. We propose that the selection of a nucleotide change at the miR172 binding site of Q contributed to subcompact spikes and free-threshing grains during wheat domestication. A nucleotide change in the microRNA172 binding site of the AP2 gene Q played a critical role in wheat domestication and the origin of free-threshing modern wheats. See also Greenwood et al. in this issue.