Dynamics of Strigolactone Function and Shoot Branching Responses in Pisum sativum
Dynamics of Strigolactone Function and Shoot Branching Responses in Pisum sativum
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DOI：
10.1093/mp/sss131
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发表时间：
2013-01-01
期刊：
影响因子：
27.5
通讯作者：
Beveridge, Christine A.
中科院分区：
文献类型：
--
作者：
Dun, Elizabeth A.;de Saint Germain, Alexandre;Beveridge, Christine A.
独脚金内酯（SL），或其代谢产物，最近被确定为内源性抑制剂的枝条分枝。然而，SL作用的某些关键特征和动力学仍有待生理学表征。在这里，我们表明，连续直接应用SL腋芽在每个节点沿着干可以完全抑制分支。SL抑制早期生长并不需要从其他生长芽或茎尖的抑制信号。除了这种非常早期或最初的抑制生长，我们还发现SL是有效的，在一定程度上，在缓和腋生分支的持续生长。SL影响芽和分支生长的有效性与SL调节PsBRC1表达的能力相关。PsBRC1是一种在腋芽中强烈表达的转录因子，是SL抑制芽分枝所必需的。与激素的动态作用相一致，SL抑制芽生长并没有阻止芽后来响应断头处理，即使SL处理后立即断头抑制生长反应。此外，正如植物中假设的分支控制网络所预期的那样，外源SL处理在2 h内引起SL生物合成基因的反馈下调。总之，这些结果揭示了新的见解SL功能的动态和支持的前提，SL或SL衍生的代谢产物的功能动态作为一个芽分支激素，他们直接在腋芽。
Strigolactones (SLs), or their metabolites, were recently identified as endogenous inhibitors of shoot branching. However, certain key features and dynamics of SL action remained to be physiologically characterized. Here we show that successive direct application of SL to axillary buds at every node along the stem can fully inhibit branching. The SL inhibition of early outgrowth did not require inhibitory signals from other growing buds or the shoot tip. In addition to this very early or initial suppression of outgrowth, we also found SL to be effective, up to a point, at moderating the continuing growth of axillary branches. The effectiveness of SL at affecting bud and branch growth correlated with the ability of SL to regulate expression of PsBRC1. PsBRC1 is a transcription factor that is expressed strongly in axillary buds and is required for SL inhibition of shoot branching. Consistent with a dynamic role of the hormone, SL inhibition of bud growth did not prevent buds from later responding to a decapitation treatment, even though SL treatment immediately after decapitation inhibits the outgrowth response. Also, as expected from the hypothesized branching control network in plants, treatment of exogenous SL caused feedback down-regulation of SL biosynthesis genes within 2 h. Altogether, these results reveal new insights into the dynamics of SL function and support the premise that SLs or SL-derived metabolites function dynamically as a shoot branching hormone and that they act directly in axillary buds.