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为了阐明水稻白叶枯病菌(Xanthomonas oryzaepv.oryzae,简称Xoo)应答调节蛋白FlgRRxoo的生物学功能,本研究通过基因克隆和序列分析、用标记交换法构建突变体以及表型测定,对flgRRxoo基因进行了分子鉴定。通过设计引物进行特异性扩增,成功地从Xoo野生型菌株PXO99A中克隆了flgRRxoo。FlgRRxoo为N端具有REC结构域的单一结构应答调节蛋白,其基因序列与其他黄单胞病菌中的同源序列高度保守。与PXO99A相比,△flgRRxoo胞外多糖(EPS)合成能力以及对水稻的毒性显著降低,基因互补可以使之恢复;△flgRRxooEPS合成基因gumBDGKM表达均有所下降;但其运动性、胞外纤维素酶和木聚糖酶活性无明显改变。表明FlgRRxoo可能主要通过调控EPS合成能力,影响了病菌在水稻上的毒性。
In order to elucidate the biological function of FlgRRxoo, a regulator of Xanthomonas oryzaepv. Oryzae (Xoo), in this study, by using gene cloning and sequence analysis, mutants and phenotypes were constructed by the marker exchange method, and the flgRRxoo gene Molecular identification. FlgRRxoo was successfully cloned from Xoo wild-type strain PXO99A by designing primers for specific amplification. FlgRRxoo is a single structural response regulator protein with an REC domain at the N-terminus and its gene sequence is highly conserved among homologous sequences in other X. oryzae bacteria. Compared with PXO99A, △ flgRRxoo exopolysaccharide (EPS) biosynthesis ability and its toxicity to rice were significantly reduced, complementarity could make it recover; △ flgRRxooEPS synthetic gene gumBDGKM expression decreased; but its motility, extracellular cellulose No significant changes in enzyme and xylanase activity. This indicated that FlgRRxoo may affect the viability of rice in rice mainly through regulating EPS synthesis ability.