Umehara Mikihisa, Hanada Atsushi, Yoshida Satoko, Akiyama Kohki, Arite Tomotsugu, Takeda-Kamiya Noriko, Magome Hiroshi, Kamiya Yuji, Shirasu Ken, Yoneyama Koichi, Kyozuka Junko, Yamaguchi Shinjiro
RIKEN Plant Science Center, Tsurumi, Yokohama 230-0045, Japan.
Nature. 2008 Sep 11;455(7210):195-200. doi: 10.1038/nature07272.
Shoot branching is a major determinant of plant architecture and is highly regulated by endogenous and environmental cues. Two classes of hormones, auxin and cytokinin, have long been known to have an important involvement in controlling shoot branching. Previous studies using a series of mutants with enhanced shoot branching suggested the existence of a third class of hormone(s) that is derived from carotenoids, but its chemical identity has been unknown. Here we show that levels of strigolactones, a group of terpenoid lactones, are significantly reduced in some of the branching mutants. Furthermore, application of strigolactones inhibits shoot branching in these mutants. Strigolactones were previously found in root exudates acting as communication chemicals with parasitic weeds and symbiotic arbuscular mycorrhizal fungi. Thus, we propose that strigolactones act as a new hormone class-or their biosynthetic precursors-in regulating above-ground plant architecture, and also have a function in underground communication with other neighbouring organisms.
茎分枝是植物结构的主要决定因素，并且受到内源和环境信号的高度调控。长期以来，人们已知两类激素，即生长素和细胞分裂素，在控制茎分枝方面发挥重要作用。此前使用一系列茎分枝增强的突变体进行的研究表明，存在一类源自类胡萝卜素的第三类激素，但其化学特性尚不清楚。在此，我们表明，在一些分枝突变体中，一类萜类内酯独脚金内酯的水平显著降低。此外，独脚金内酯的施用会抑制这些突变体中的茎分枝。独脚金内酯此前在根分泌物中被发现，作为与寄生杂草和共生丛枝菌根真菌的通讯化学物质。因此，我们提出独脚金内酯作为一类新的激素——或者其生物合成前体——在调节地上部植物结构中发挥作用，并且在与其他邻近生物体的地下通讯中也具有功能。
