水稻几丁质酶基因的转录与表达特征

Transcriptional and Translational Characterization of Rice Chitinase Genes

几丁质酶与植物的生长发育、抗逆和防御反应相关。水稻PR3家族几丁质酶编码基因有19个成员,本文分析其转录特征,了解到有些基因属于组成型转录,有些基因属于组织特异型转录,分析几丁质酶蛋白质的结构域,并对其进行聚类和亚家族分类。利用免疫印迹技术分析几丁质酶蛋白质的表达谱,发现CHIT5的表达量在水稻叶片生长过程中下调,而CHIT6、CHIT14、CHITC1和CHITC2的表达量上调。在水稻与白叶枯病菌(Xoo)的不亲和反应中,CHIT1、CHIT2、CHIT5、CHIT6、CHIT10、CHIT15和CHIT16的表达量上调,CHIT14、CHITC1和CHITC2的表达下调。进一步比较几丁质酶蛋白质在水稻-Xoo不同互作反应中的表达,发现其在亲和及不亲和反应中的表达模式类似,但一般在亲和反应中强度变化较大。此外,CHIT6蛋白质在对照反应中的表达量上调,提示CHIT6的表达受创伤的诱导。本文比较系统地揭示了水稻PR3家族几丁质酶编码基因的转录和蛋白质表达特征,为其功能解析提供了线索。

Plant chitinases play roles in plant development and stress responses. Nineteen chitinase genes, belonging to patho- genesis related PR3 family, were found in rice genome. In this study, constitutive and tissue-specific transcripted chitinase genes were identified, and the domain architecture of chitinase protein was predicted. Clustering analysis and subfamily classification were also carried out. Furthermore, chitinase protein expression profiling was surveyed using western blot （WB）, it was found that the expression of CHIT5 was down-regulated in normal growth rice leaves, while the expressions of CHIT6, CHIT14, CHITC1, and CHITC2 were up-regulated. In the incompatible interaction between rice and Xanthomonas oryzae pv. oryzae （Xoo）, the ex- pressions of CHIT1, CHIT2, CHIT5, CHIT6, CHITI0, CHIT15, and CHIT16 were enhanced after inoculation and three of CHIT14, CHITC1 and CHITC2 down-regulated. In addition, the comparison of chitinase protein expression in different rice-Xoo interactions showed that these were similar alternation patterns between compatible and incompatible reactions, with a higher extent of alterations in incompatible interactions for most of chitinases. It is interesting to note that the expression of CHIT6 was enhanced in mock-treated samples, suggesting that the expression of CHIT6 may be induced by a mechanic wound. The data revealed in this research will provide useful clues for the understanding of the function of PR3 family chitinase genes.