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由水稻黄单胞菌引起的水稻白叶枯病是水稻最严重的细菌性病害。通过筛选18000个XooTn5转座子插入突变体,得到其中一个致病力缺失的突变体XOG11。TAIL-PCR方法分离该突变体中插入转座子的侧翼序列,发现转座子插入到位于hrp基因簇的hpaB基因中。对该基因进一步的分析表明该基因编码一个含有156个氨基酸,等电点为4.28,亮氨酸含量为14.4%的蛋白HpaB。Southern blot和PCR验证表明Tn5在该突变体中为单拷贝插入且未发生转座子携带侧翼序列的转移。将hpaB克隆到具有广泛寄主的质粒pHM1中,转化重组质粒进入突变体后,突变体恢复了在其寄主水稻IR24上的致病力,而转化空质粒pHM1后的突变体仍然表现为致病力缺失。证实了水稻黄单胞菌中hpaB基因与该细菌的致病力相关,在侵染水稻的过程中起着不可缺失的作用。
Rice bacterial blight caused by X. aeruginosa is the most serious bacterial disease in rice. By selecting 18,000 XooTn5 transposons for insertion into the mutant, one of the mutants, XOG11, that lack virulence was obtained. The TAIL-PCR method was used to isolate the transposon flanking sequence in this mutant. The transposon was found to be inserted into the hpaB gene located in the hrp gene cluster. Further analysis of this gene revealed that the gene encodes a protein HpaB containing 156 amino acids with an isoelectric point of 4.28 and a leucine content of 14.4%. Southern blot and PCR validation demonstrated that Tn5 was inserted as a single copy in this mutant and no transfer of transposon-carrying flanking sequences occurred. The hpaB was cloned into the plasmid pHM1 with a wide range of hosts. After the recombinant plasmid was transformed into the mutant, the mutant restored the virulence on its host rice IR24, while the mutant transformed with the empty plasmid pHM1 still showed virulence Missing. It was confirmed that the hpaB gene in X. aeruginosa is related to the pathogenicity of this bacterium and plays an indispensable role in the process of infecting rice.