1887

Abstract

Genes in the regulon encode component proteins of the type III secretion system and are essential for the pathogenicity of . The regulon is controlled by HrpB. We isolated several genes regulating expression from the Japanese strain OE1-1 using minitransposon mutagenesis. Among them, we mainly focused on two genes, and , which are the positive regulators of . Although the global virulence regulator PhcA negatively regulated expression via , it positively regulated expression. We further investigated the contrasting regulation of and by PhcA and speculated that may switch from HrpG to PrhG for activation in a cell density-dependent manner. Although the mutant proliferated similarly to the wild-type in leaf intercellular spaces and in xylem vessels of the host plants, it was less virulent than the wild-type. The expression of the operon, which belongs to the regulon, was significantly reduced in the mutant by more than half in the leaf intercellular spaces and more than two-thirds in the xylem vessels when compared with the wild-type.

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2013-08-01
2019-10-23
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