橡胶树水通道蛋白基因HbPIP1和HbPIP2的功能鉴定及其表达分析

Functional Characterization and Expression Analysis of Aquaporin Genes(HbPIP1 and HbPIP2)in Hevea brasiliensis

利用非洲爪蟾卵母细胞对橡胶树水通道蛋白基因HbPIP1和HbPIP2进行功能鉴定,发现HbPIP1具有快速水分传输功能而HbPIP2不具该功能。推测HbPIP1基因表达可能与乙烯利刺激橡胶树增产机制有关。因此,选择对乙烯利较敏感的橡胶树PR107品种,利用RT-qPCR和Western blot技术检测HbPIP1在转录和翻译水平的表达变化,探讨其与乙烯利刺激后橡胶树排胶体积、排胶时间、干含和总固形物变化的关系。结果表明:HbPIP1在树皮、胶乳和次生木质部中具有较高的表达量;胶乳中HbPIP1的表达量随乙烯利刺激时间延长呈上升趋势,而树皮中HbPIP1的表达量则呈降低的趋势;乙烯利通过调节HbPIP1的基因表达促进水分向乳管细胞的运输,从而降低胶乳干含和总固形物,延迟排胶时间,增加排胶体积和产量。

In this study,Xenopus laevis oocytes were used to test the functional characterization of our previously cloned HbPIP1 and HbPIP2 aquaporin genes from rubber trees （Hevea brasiliensis）.The result showed that HbPIP1 had the function of transmembrane water transport however HbPIP2 has not.We therefore infer that HbPIP1 is involved in the mechanism of Ethrel-induced latex promotion.An Ethrel sensitive rubber clone PR107 was selected as the plant material.The gene expression profiles of HbPIP1 at both transcript level and translation level were examined by RT-qPCR and Western blot to investigate their link with the effect of Ethrel on latex flow duration,latex volume,dry rubber content （DRC） and total solids content （TSC）.It was found that the expression of HbPIP1 in latex,bark and xylem was higher than that in petioles and blades of various periods.The expression of HbPIP1 in PR107 latex presented an increase trend with the Ethrel treatment duration,while it was down-regulated in the bark.This expression might facilitate the water transport into rubber laticifers and therefore can decrease latex DRC and TSC,prolong latex flow and enhance the latex yield.