植物荫蔽胁迫的激素信号响应

doi:10.11983/CBB17014

摘要/Abstract

摘要： 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。

关键词: 植物激素, 荫蔽, 下胚轴, 生长素, 赤霉素, 油菜素甾醇

Abstract: 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.

Key words: phytohormones, shade, hypocotyl, auxin, gibberellin, brassinosteroid

帅海威, 孟永杰, 陈锋, 周文冠, 罗晓峰, 杨文钰, 舒凯. 植物荫蔽胁迫的激素信号响应. 植物学报, 2018, 53(1): 139-148.

Haiwei Shuai, Yongjie Meng, Feng Chen, Wenguan Zhou, Xiaofeng Luo, Wenyu Yang, Kai Shu. Phytohormone-mediated Plant Shade Responses. Chinese Bulletin of Botany, 2018, 53(1): 139-148.

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链接本文: https://www.chinbullbotany.com/CN/10.11983/CBB17014

https://www.chinbullbotany.com/CN/Y2018/V53/I1/139

图/表 1

图1 几种重要植物激素响应荫蔽胁迫的信号通路网络荫蔽胁迫下, 光敏色素由活化态Pfr形式转变为非活化态Pr形式, 由此减弱对PIFs的抑制作用。不同植物激素对荫蔽胁迫的响应不同, 但最终都会与PIFs产生互作。在荫蔽胁迫下, 赤霉素(GA)合成基因GA3ox和GA20ox的表达量增加, 进而导致GA含量升高, GA含量的增加又会促进DELLA蛋白的降解, 而DELLA蛋白能抑制PIF4行使功能。油菜素甾醇(BR)合成基因ROT3在荫蔽胁迫下表达量也会增加, 进而促进BR含量的升高, BR的增加能促进BR转录因子基因BZR1的转录, 而BZR1能与PIF4蛋白产生结构上的互作。在荫蔽胁迫下, 乙烯(ETH)的含量也会增加, ETH的增加能促进ETH转录因子基因EIN3的转录, 而EIN3被证明能上调PIF3基因的表达。生长素(IAA)的合成和信号转导均受PIFs的影响, 其中PIF4、PIF5和PIF7对IAA的合成具有促进作用, 且PIF4和PIF5还促进IAA下游转录因子基因ARF6的表达, IAA也是促进下胚轴伸长的主要植物激素。荫蔽胁迫下, 不同信号通路之间存在互作关系。例如, 在调控下胚轴伸长时, PIF4、BZR1和ARF6被证明具有协同作用。

Figure 1 The proposed plant shade response signaling networks mediated by several important phytohormones Phytochrome is transferred from active Pfr to inactive Pr statuses under shade conditions, and this further attenuates the inhibition effect on PIFs. Although the shade response is distinct among different phytohormones, finally the interaction between all phytohormones with PIFs is documented. Under shade conditions, the transcription level of GA biosynthesis genes GA3ox and GA20ox were increased, which further promotes degradation of DELLA and finally inhibits the functions of PIFs. The expression of BR biosynthesis gene ROT3 is also increased under shade conditions, and further enhances BR biosynthesis and promotes BZR1 transcription, and finally the interaction between BZR1 and PIF4 was detected. Similar to GA and BR, ethylene level was also increased under shade conditions. The increase of ethylene then induces EIN3 transcription, and transcription factor EIN3 further enhances the transcription of PIF3. Both auxin biosynthesis and signaling pathways are regulated by PIFs; in detail, PIF4, PIF5 and PIF7 enhance IAA biogenesis, and PIF4 and PIF5 also promote ARF6 expression. So far, auxin is the most important phytohormone mediates plant shade response. In a word, under shade conditions, the crosstalk networks among different phytohormones signaling pathways were documented. For example, the synergy effect of PIF4, BZR1 and ARF6 was detected under shade conditions, with regard to hypocotyl elongation.

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