Carlactone-independent seedling morphogenesis in Arabidopsis
Carlactone-independent seedling morphogenesis in Arabidopsis
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DOI：
10.1111/tpj.12265
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发表时间：
2013-10-01
期刊：
影响因子：
7.2
通讯作者：
Smith, Steven M.
中科院分区：
文献类型：
--
作者：
Scaffidi, Adrian;Waters, Mark T.;Smith, Steven M.
独脚金内酯激素通过己内酯衍生自类胡萝卜素，并通过β-水解酶D14和F-盒蛋白D3/MAX2起作用以抑制植物芽分支。虽然MAX2也是正常的幼苗发育所必需的，但D14和已知的独脚金内酯生物合成基因不是，这就提出了一个问题，即内源性的、规范的独脚金内酯是否来源于己内酯，在幼苗形态发生中起作用。在这里，我们报告的独脚金内酯前体carlactone的化学合成，并表明，它抑制拟南芥芽分支和影响叶形态建成通过依赖于细胞色素P450 MAX 1的机制。相比之下，生理活性的Z-己内酯和非生理E异构体在幼苗中表现出类似的弱活性，并且主要通过D14而不是其副产物KAI 2以MAX2依赖但MAX 1独立的方式发出信号。KAI 2是必不可少的幼苗形态建成，因此，这一早期阶段的发展采用carlactone独立的形态，其中karrikins从野火烟雾是特定的替代品。虽然通常使用的合成独脚金内酯GR 24通过D14和KAI 2两者非特异性地起作用，但carlactone是独脚金内酯信号传导的特异性效应物，其通过MAX 1和D14起作用。
Strigolactone hormones are derived from carotenoids via carlactone, and act through the /-hydrolase D14 and the F-box protein D3/MAX2 to repress plant shoot branching. While MAX2 is also necessary for normal seedling development, D14 and the known strigolactone biosynthesis genes are not, raising the question of whether endogenous, canonical strigolactones derived from carlactone have a role in seedling morphogenesis. Here, we report the chemical synthesis of the strigolactone precursor carlactone, and show that it represses Arabidopsis shoot branching and influences leaf morphogenesis via a mechanism that is dependent on the cytochrome P450 MAX1. In contrast, both physiologically active Z-carlactone and the non-physiological E isomer exhibit similar weak activity in seedlings, and predominantly signal through D14 rather than its paralogue KAI2, in a MAX2-dependent but MAX1-independent manner. KAI2 is essential for seedling morphogenesis, and hence this early-stage development employs carlactone-independent morphogens for which karrikins from wildfire smoke are specific surrogates. While the commonly employed synthetic strigolactone GR24 acts non-specifically through both D14 and KAI2, carlactone is a specific effector of strigolactone signalling that acts through MAX1 and D14.