Localized hormone fluxes and early haustorium development in the hemiparasitic plant Triphysaria versicolor
Localized hormone fluxes and early haustorium development in the hemiparasitic plant Triphysaria versicolor
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DOI：
10.1104/pp.104.057836
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发表时间：
2005-07-01
期刊：
影响因子：
7.4
通讯作者：
Yoder, JI
中科院分区：
文献类型：
--
作者：
Tomilov, AA;Tomilova, NB;Yoder, JI
也许最明显的表型与植物之间的化学信号相关的表现是寄生种的龙葵科。吸器是一种侵入性的根结构，它允许半寄生植物从自养生长过渡到异养生长，它的发育是快速的、高度同步的，并且很容易在体外观察到。当暴露于与寄主根分泌物和根际生物活性相关的酚分子时，兼性寄生虫花斑三泡菌的无菌根中开始了吸器的发育。早期吸器本体发育的形态学特征包括根部伸长、扩张和表皮细胞分化为吸器毛的迅速停止，以及皮层细胞的扩张。这些发育过程通过外源植物激素的施用而受到刺激，通过激素拮抗剂的施用而受到抑制。如果根在解剖前暴露于吸器诱导因素，手术切除的根尖会形成吸器。相比之下，在诱导因子处理前切开的根尖除非补充吲哚-3-乙酸，否则无法形成吸器。瞬时转化实验表明，当暴露于外源激素或纯化的吸器诱导因子时，T. versicolor的生长素和乙烯响应启动子上调。这些实验表明，局部生长素和乙烯积累是吸器发育的早期事件，寄生植物利用已建立的植物发育机制来实现寄生虫的特定功能。
Perhaps the most obvious phenotypes associated with chemical signaling between plants are manifested by parasitic species of Orobanchaceae. The development of haustoria, invasive root structures that allow hemiparasitic plants to transition from autotrophic to heterotrophic growth, is rapid, highly synchronous, and readily observed in vitro. Haustorium development is initiated in aseptic roots of the facultative parasite Triphysaria versicolor when exposed to phenolic molecules associated with host root exudates and rhizosphere bioactivity. Morphological features of early haustorium ontogeny include rapid cessation of root elongation, expansion, and differentiation of epidermal cells into haustorial hairs, and cortical cell expansion. These developmental processes were stimulated in aseptic T. versicolor seedlings by the application of exogenous phytohormones and inhibited by the application of hormone antagonists. Surgically dissected root tips formed haustoria if the root was exposed to haustorial-inducing factors prior to dissection. In contrast, root tips that were dissected prior to inducing-factor treatment were unable to form haustoria unless supplemented with indole-3-acetic acid. A transient transformation assay demonstrated that auxin and ethylene-responsive promoters were up-regulated when T. versicolor was exposed to either exogenous hormones or purified haustoria-inducing factors. These experiments demonstrate that localized auxin and ethylene accumulation are early events in haustorium development and that parasitic plants recruit established plant developmental mechanisms to realize parasite-specific functions.