Q21介导花粉与柱头相互作用的分子机制研究

In plants, double fertilization is a key process of plant sexual reproduction, and in this process, correct recognition between pollen and stigma is a prerequisite for successful fertilization. Therefore, the molecular regulatory mechanism underlying the process is one of the core questions in the field of plant developmental biology. Early rearseaches indicated that during the process of pollen adhesion and hydration, the interaction of pollen and stigma might occur. However，so far the molecular mechanism regulating the interaction between pollen and stigma is largely unknown and needs to be explored. In our previous work, a hydration-defective mutant called q21/Q21 was identified and the mutant pollen cannot hydrate when pollinated on the wild-type stigma, but in high humidity it can hydrate and germinate. Moreover, q21 pollen grain showed no discernible abnormalities and could germinate normally in vitro. Thus it is likely that Q21 could take part in the interaction between pollen and stigma for hydration completion, which provides an opportunity for us to study the molecular mechanism of pollen and stigma interaction. In this project, we will focus on Q21 functioning in the recognition between pollen and stigma, and hope to provide new insight in understanding the molecular mechanism of pollen and stigma interaction in plants.

植物的双受精是有性生殖关键的过程。其中，花粉与柱头的正确识别是完成双受精过程的前提与保障，长期以来其分子调控机制一直是植物有性生殖研究领域的热点及核心问题之一。早期研究表明在花粉粘附和水合两个过程中，花粉与柱头之间可能存在相互识别，然而其具体的分子调控机制，迄今仍知之甚少。在前期的研究过程中，我们鉴定到一个水合缺陷突变体q21/Q21。q21/Q21突变体花粉发育正常并且体外能够正常萌发；当突变体花粉授到野生型柱头上，花粉不能水合，然而在高湿度下突变体花粉能够水合并且萌发。这些表型暗示了Q21参与了花粉与柱头的相互识别过程，同时也证实了这种识别是花粉水合必需的。这为我们探讨花粉与柱头相互作用的分子调控机制提供了难得的契机。本项目拟以q21/Q21突变体为切入点，探讨Q21在花粉与柱头相互识别中的作用，从而揭示花粉与柱头相互作用的具体途径，为认识植物花粉与柱头相互作用的分子机理提供突破点。

在植物有性生殖过程中，花粉与柱头的正确识别是确保花粉萌发、完成受精的重要环节，长期以来备受人们的关注。然而, 其具体的分子信号调控途径目前尚不清楚。我们筛选并鉴定到一个水合缺陷突变体q21/Q21，确认一类JAZ（Jasmonate ZIM domain）蛋白可以与Q21相互作用。进一步的分析表明由于T-DNA的插入,在突变体花粉中存在一个短的转录本Q21-2，其可以削弱JAZ11蛋白与COI1 (CORONATINE INSENSITIVE1) 的结合，并且在体内证明了相比于野生型，突变体花粉中JAZ11蛋白对JA更不敏感，表明q21花粉中JA信号途径受阻。此外，JA相关突变体(opr3 和coi1)的柱头在接受亲和花粉方面存在缺陷，同时有一半的coi1花粉在野生型柱头上不能水合。这些结果充分说明Q21通过茉莉酸信号通路调控花粉与柱头的相互作用，同时证明了在花粉与柱头相互作用过程中，JA很可能作为一个新的交流信号分子，来调控花粉水合过程。因此，我们的研究结果解析了一条新的调控花粉与柱头相互作用的途径，回答了亲和花粉如何在柱头上得以水合，为解析花粉与柱头相互作用提供了新思路。