天然橡胶在橡胶树的乳管细胞中特异合成，并在割胶过程中以胶乳（即细胞质）的形式被排出。胶乳的含水量高达70%，水分通过调节胶乳的粘稠度和乳管膨压进而影响橡胶树的产排胶能力，是决定胶乳产量的关键因素。由于用于割胶的成熟乳管与邻近的薄壁细胞间不存在胞间连丝，故水分只能通过水通道蛋白进入乳管。我们前期的研究表明，橡胶树含有51个水通道蛋白基因，而单细胞类型乳管组织的水分平衡主要由受乙烯诱导的HbPIP2;3介导。为揭示HbPIP2;3调控乳管水分平衡的分子机制，本项目拟采用split-ubiquitin酵母双杂交和双分子荧光互补相结合的方法筛选与HbPIP2;3互作的PIP类蛋白；研究蛋白互作对HbPIP2;3水分转运活性的影响；分离和鉴定调控HbPIP2;3响应乙烯利刺激的转录因子。项目的实施不仅可为水分高效利用高产品种的选育创造条件，同时还可为新型产排胶调节剂的研发提供理论基础和技术支撑。

Natural rubber (cis-1,4-polyisoprene), an important industrial raw material, is specially synthesized in the highly differentiated vessels termed laticifers in rubber tree (Hevea brasiliensis Muell. Arg.). Upon bark tapping, rubber is expelled out in the form of latex which represents the cytoplasmic content of laticiferous cells. Water, accounting for approximately 70% of the latex upon each tapping, plays a crucial role in latex production by regulating the latex viscosity and laticifer turgor. Due to devoid of functional plasmodesmata with neighboring parenchyma cells, the water inflow into laticifers is mainly governed by aquaporins (AQPs). Our previous studies indicated that the rubber genome encodes 51 AQP genes, and the water balance of the single-type-tissue laticifer was mainly controlled by one ethylene-induced AQP gene named HbPIP2;3. To reveal the regulation mechanisms of HbPIP2;3 in laticifer water balance, in this project, split-ubiquitin based membrane yeast two-hybrid (MYTH) and bimolecular fluorescence complementation (BiFC) are carrying out to identify PIP proteins that can interact with HbPIP2;3; to study the effects of interacting proteins in the regulation of water transport activity of HbPIP2;3; and, to identify transcription factors that mediate the response of HbPIP2;3 to ethephon stimulation. This study promises to lay a solid foundation not only for molecular assisted breeding on yield and efficient use of water, but also for the development of new latex stimulators.