Analysis of the Rac/Rop Small GTPase Family in Rice: Expression, Subcellular Localization and Role in Disease Resistance
Analysis of the Rac/Rop Small GTPase Family in Rice: Expression, Subcellular Localization and Role in Disease Resistance
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DOI：
10.1093/pcp/pcq024
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发表时间：
2010-04-01
影响因子：
4.9
通讯作者：
Shimamoto, Ko
中科院分区：
文献类型：
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作者：
Chen, Letian;Shiotani, Kenji;Shimamoto, Ko
植物特异性Rac/Rop小GTP酶作为分子开关在包括防御反应在内的许多信号转导事件中发挥作用。为了了解Rac/Rop家族7个成员在水稻中的功能，我们采用半定量逆转录PCR（RTPCR）技术研究了Rac/Rop基因在水稻中的组织特异性表达模式，并利用绿色荧光蛋白（GFP）融合蛋白在瞬时表达系统中进行了Rac/Rop基因的亚细胞定位。我们还研究了这些基因在抗病性中的作用，通过测试单一的Rac/Rop-RNAi（RNA干扰）植物对稻瘟病病原体稻瘟病菌。我们的研究表明OsRac 2、6和7在叶片中的表达量很低，并揭示了Rac/Rop GTP酶多碱基区的赖氨酸和/或精氨酸（KR）残基的数量与它们在体内的亚细胞分布之间的强相关性。感染试验表明，OsRac 1是稻瘟病抗性的正调控因子，证实了以前的观察，而OsRac 4和OsRac 5是稻瘟病抗性的负调控因子。OsRac 6可能对抗病性有较小的贡献，而OsRac 3和OsRac 7可能不参与防御。因此，我们的研究表明，水稻Rac/Rop家族在不同的细胞活动中发挥着多重作用，在抗病性方面既有积极的作用，也有消极的作用。
Plant-specific Rac/Rop small GTPases function as molecular switches for numerous signal transduction events, including defense responses. To understand the function of each of the seven Rac/Rop family members in rice, we studied the tissue-specific expression patterns of Rac/Rop genes by semi-quantitative reverse transcriptionPCR (RTPCR), and also Rac/Rop subcellular localization using green fluorescent protein (GFP) fusion proteins in transient expression systems. We also investigated the roles of these genes in disease resistance by testing single Rac/Rop-RNAi (RNA interference) plants against the rice blast pathogen Magnaporthe grisea. Our studies show that expression of OsRac2, 6 and 7 is very low in leaf blades, and reveal a strong correlation between the number of lysine and/or arginine (KR) residues in the polybasic region of Rac/Rop GTPases and their subcellular distribution invivo. Infection assays showed that OsRac1 is a positive regulator of blast resistance, confirming previous observations, whereas OsRac4 and OsRac5 are negative regulators of blast resistance. OsRac6 may make minor contributions to disease resistance, while OsRac3 and OsRac7 are probably not involved in defense. Therefore, our study suggests that the rice Rac/Rop family plays multiple roles in diverse cellular activities and has both positive and negative functions in disease resistance.