拟南芥RAB5调控花粉管生长的功能和机理研究

花粉管极性生长是保障植物雄配子体育性和双受精顺利完成的前提。液泡在花粉管生长过程中至关重要，RAB5作为介导液泡运输的主要调控因子影响液泡的形成及动态变化。申请人前期研究发现RAB5成员RHA1和ARA7双突变后，雄配子体无法传代，初步分析表明RAB5介导了花粉管生长过程。然而RAB5通过影响花粉管生长调控雄配子体育性的机理尚不清楚。本项目拟利用遗传学、细胞生物学、分子生物学等技术手段揭示RAB5对花粉管中液泡发生及动态的影响，解析花粉管生长过程中液泡运输途径与ROP信号等细胞活动的关系，阐明RAB5介导花粉管生长的机理。本项目的开展可以揭示RAB5调控雄配子体育性方面的功能，有助于深入了解液泡在花粉管极性生长中的作用机理，并为理解液泡对于其它细胞活动的影响提供新的信息。

The development of male gametophytes and pollen tube growth are critical pre-requisites for double fertilization of angiosperms. Vacuolar biogenesis, trafficking, and dynamics are essential for the survival of plant cells. Three vacuolar trafficking routes have been reported in plant cells, which are mediated by RAB5, by RAB5-RAB7, or by AP-3. Our laboratory previously reported that functional loss of the AP-3-mediated vacuolar trafficking pathway compromised pollen tube growth. However, whether RAB5-dependent vacuolar trafficking routes are involved in pollen development and pollen tube growth is unclear..In Arabidopsis, two genes, RHA1 and ARA7, encode the canonical RAB5. Although extensive studies have demonstrated their roles in regulating vacuolar trafficking, their physiological role in plant development has yet to be characterized. .By using a reverse genetic approach, we aimed to characterized the functionality of Arabidopsis RAB5 members RHA1 and ARA7. Our preliminary results indicated that RAB5 is essential for male gametophytic functionality such that male gametophytes carrying the rha1;ara7 genotype could not be transmitted. We also have data suggesting that functional loss of the canonical RAB5 compromised pollen tube growth..In this study, we propose to 1) understand the role of RAB5 in male gametophytic function; 2) uncover the influence of RAB5-mediated trafficking on vacuolar dynamics in pollen tubes; 3) understand the influence of RAB5-mediated vacuolar trafficking on other key intracellular activities during pollen tube growth. Our results will not only provide novel insights into how RAB5 regulates male gametophytic function, but also give clues to the influence of vacuolar trafficking on other intracellular activities.