POD1调控被子植物花粉管导向的分子机理研究

The sexual reproduction of flowering plants largely relies on the successful delivery of sperm cells by the pollen tube to the embryo sac, a phenomenon called pollen tube guidance. Pollen tube guidance is a cell-cell communication process between the pollen tube and the pistil and the embryo sac. The pollen tube perceives and responds to the attracting signal derived from the female tissues to achieve directional growth towards the embryo sac. Peptides have been identified as the female attracting signal in some plant species, however, how the pollen tube perceives and responds to the signal is still unknown. Our previous work proved that mutations in POLLEN DEFECTIVE IN GUIDANCE 1 (POD1) gene, encoding an ER luminal protein that interacts with the ER chaperone CALRETICULIN 3(CRT3), abolish micropylar pollen tube response in Ararbidopsis. It suggests that ER plays a critical role in pollen tube guidance. Based on these findings, we propose to further decipher POD1's role in pollen tube guidance by the identification and functional study on POD1 interacting partners and candidates that are regulated by the POD1-CRT3 complex. The results of the study will provide insights into the molecular mechanism controlling pollen tube guidance in flowering plants, and also new ideas on enhancing reproduction efficiency and breeding in crops.

被子植物受精过程中，花粉中的精细胞不能自主运动，需依赖花粉管的定向生长传送到胚囊，来完成受精。花粉管朝向胚囊定向生长的过程称为花粉管导向。在花粉管导向过程中，花粉管通过接受雌蕊及胚囊分泌的吸引信号并作出响应，来实现定向生长。胚囊分泌的吸引信号已被证实为多肽类分子，但花粉管如何接受该吸引信号并对其作出响应的机理还不清楚。研究表明，内质网蛋白在花粉管响应信号过程中起重要作用。我们在前期工作中，发现一个新的与分子伴侣CALRETICULIN3（CRT3）相互作用的内质网蛋白POLLEN DEFFECTIVE IN GUIDANCE1（POD1）特异地控制花粉管对胚囊信号的响应。本项目旨在研究POD1的作用机理，对POD1与其它蛋白的相互作用以及POD1参与内质网蛋白滞留的方式等关键问题进行探讨。研究结果将有助于深入解析花粉管响应吸引信号的分子机理，并为打破生殖隔离和提高杂交育种效率提供理论依据。

本项目旨在研究POD1调控花粉管响应胚囊信号的作用机制，探索POD1 与其它蛋白的相互作用及其分子机理。通过互作蛋白筛选得到三个POD1互作蛋白ECO，并对ECO的功能及作用机制进行了系统的研究。 研究发现ECO是一个全新的内质网结构调控蛋白，并发现了ECO整合内质网质量控制体系及调控LRR-RLK受体蛋白的分泌。该结果提出了POD1-CRT3-ECO蛋白复合体在调控营养生长及花粉管生长和导向过程中的分子模型。

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