Inhibition of Tiller Bud Outgrowth in the tin Mutant of Wheat Is Associated with Precocious Internode Development
Inhibition of Tiller Bud Outgrowth in the tin Mutant of Wheat Is Associated with Precocious Internode Development
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DOI：
10.1104/pp.112.197954
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发表时间：
2012-09-01
期刊：
影响因子：
7.4
通讯作者：
Spielmeyer, Wolfgang
中科院分区：
文献类型：
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作者：
Kebrom, Tesfamichael H.;Chandler, Peter M.;Spielmeyer, Wolfgang
分蘖(分枝)是产量的主要组成部分，因此也是提高作物产量的目标。然而，分蘖受到内源信号和环境信号的复杂相互作用的调控，通过遗传和农艺手段获得最佳分蘖数所需的知识仍然缺乏。通过对主要作物中自然发生的和诱导的分蘖突变体进行生理和分子鉴定，可以揭示其调控机制。在这里，我们描述了小麦(Triticum Aestivum)的一个减少分蘖(TIN，用于抑制分蘖)突变体。TIN的分蘖减少是由于枝尖从营养生长阶段向生殖阶段过渡期间分蘖芽生长提前停止所致。TIN与野生型在主茎顶端发育上无明显差异。然而，TIN启动节间发育的时间较早，与野生型不同，TIN的节间是实心的而不是中空的。我们推测，TIN代表了一种新型的减少分蘖的突变体，与早熟节间伸长相关，这种突变体将蔗糖(Suc)从发育中的分蘖中转移出来。与这一假设一致，我们观察到了Suc饥饿诱导的基因上调，Suc诱导基因的下调，以及休眠锡芽中Suc含量的减少。小麦休眠相关基因(DRM1-like)和teosinte Branched1(Tb1-like)基因的表达增加，细胞周期基因的表达降低，也表明TIN处于芽休眠状态。这些结果突出了Suc在枝条分枝中的重要性，以及通过操纵节间伸长的时间来优化分蘖的可能性。
Tillering (branching) is a major yield component and, therefore, a target for improving the yield of crops. However, tillering is regulated by complex interactions of endogenous and environmental signals, and the knowledge required to achieve optimal tiller number through genetic and agronomic means is still lacking. Regulatory mechanisms may be revealed through physiological and molecular characterization of naturally occurring and induced tillering mutants in the major crops. Here we characterize a reduced tillering (tin, for tiller inhibition) mutant of wheat (Triticum aestivum). The reduced tillering in tin is due to early cessation of tiller bud outgrowth during the transition of the shoot apex from the vegetative to the reproductive stage. There was no observed difference in the development of the main stem shoot apex between tin and the wild type. However, tin initiated internode development earlier and, unlike the wild type, the basal internodes in tin were solid rather than hollow. We hypothesize that tin represents a novel type of reduced tillering mutant associated with precocious internode elongation that diverts sucrose (Suc) away from developing tillers. Consistent with this hypothesis, we have observed upregulation of a gene induced by Suc starvation, downregulation of a Suc-inducible gene, and a reduced Suc content in dormant tin buds. The increased expression of the wheat Dormancy-associated (DRM1-like) and Teosinte Branched1 (TB1-like) genes and the reduced expression of cell cycle genes also indicate bud dormancy in tin. These results highlight the significance of Suc in shoot branching and the possibility of optimizing tillering by manipulating the timing of internode elongation.