植物荫蔽胁迫的激素信号响应

植物的生长发育与光信号密切相关, 外界光强、光质的变化会改变植物的生长发育状态。在自然或人工生态系统中, 植株个体的光环境往往会被其周围植物所影响, 导致荫蔽胁迫, 其主要表现为光合有效辐射以及红光与远红光比值(R:FR)降低。荫蔽胁迫对植物生长发育的多个时期均有影响, 如抑制种子萌发、促进幼苗下胚轴伸长及促进植物花期提前等, 这对农业生产不利, 会导致作物产量以及品质的降低。植物激素是调控植物生长发育的关键内源因子。大量研究表明, 生长素(IAA)、赤霉素(GA)及油菜素甾醇(BR)等植物激素均参与介导植物的荫蔽胁迫响应。当植物处于荫蔽胁迫时, 光信号的改变会影响植物激素的合成及信号转导。不同植物激素对荫蔽胁迫的响应各不相同, 但其信号通路之间却存在互作关系, 从而形成复杂的网络状调控路径。该文总结了几种主要植物激素(生长素、赤霉素、油菜素甾醇及乙烯)响应荫蔽胁迫的机理, 重点论述了荫蔽胁迫对植物激素合成及信号通路的影响, 以及植物激素调控荫蔽胁迫下植物生长的分子机理, 并对未来潜在的研究热点进行了分析。

Phytohormone-mediated Plant Shade Responses

Plant survival and reproduction are closely related to light signal transduction. Both light intensity and light quality regulate plant growth and development. In natural or artificial ecosystems, the light received by an individual plant can be modified by its neighbors, and the photosynthetically active radiation and ratio of red light to far red light (R:FR) will significantly decrease, called shade. Shade stress has many effects during distinct stages of plant growth and development, including seed germination inhibition, seedling hypocotyl elongation and early flowering. Subsequently, shade decreases crop yield and quality; thus, it is unfavorable for agricultural production. Phytohormones are key endogenous factors in regulating plant growth and development. Numerous studies demonstrated that auxin, gibberellin and brassinosteroids are involved in the shade stress response. Under shade conditions, light signaling will be perceived and integrated by the plant, and the integrated signal can affect the biosynthesis and signal transduction of phytohormones. Different phytohormones have distinct pathways in response to shade stress. The crosstalk among phytohormone signaling pathways under shade stress are still unclear. In this review, we summarize the mechanisms of response of the main phytohormones (auxin, gibberellin, brassinosteroid) to shade stress, then the effects of shade on phytohormone synthesis and signal transduction, and the molecular mechanism of phytohormone regulation of growth of plants under shade stress. Finally, we propose future research directions.