The HrpX Protein Activates Synthesis of the RaxX Sulfopeptide, Required for Activation of XA21-Mediated Immunity to Xanthomonas oryzae pv. oryzae
The HrpX Protein Activates Synthesis of the RaxX Sulfopeptide, Required for Activation of XA21-Mediated Immunity to Xanthomonas oryzae pv. oryzae
复制标题
DOI：
10.1094/mpmi-05-21-0124-r
复制
发表时间：
2021-11-01
影响因子：
3.5
通讯作者：
Ronald, Pamela C.
中科院分区：
文献类型：
--
作者：
Joe, Anna;Stewart, Valley;Ronald, Pamela C.
在遇到易感植物宿主时，细菌病原体表达特异性毒力因子。例如，在植物中，黄单胞菌HrpX蛋白激活大约150个基因的转录，所述基因编码III型分泌系统的组分或其易位效应物，以及与发病机理有关的其它分泌蛋白。在这里，我们展示X。oryzaepv.稻在植物中或在HrpX诱导的XOM 2培养基中的生长导致了raxX和raxST基因的HrpX依赖性转录，所述基因控制通过I型分泌系统输出的RaxX磺肽的产生。在Xa 21（+）水稻品系中，RaxX蛋白是激活XA 21介导的免疫所必需的。我们鉴定了raxX和raxST转录物的可能5“端上游的潜在植物诱导型启动子元件。缺失和核苷酸取代证实了这些元件是raxX和raxST的HrpX依赖性表达所必需的。我们得出结论，raxX-raxST基因表达在植物生长过程中由HrpX诱导，因此与致病所需的其他基因协同表达。
Upon encountering a susceptible plant host, a bacterial pathogen expresses specific virulence factors. For example, in planta, the Xanthomonas HrpX protein activates transcription of roughly 150 genes encoding components of the type III secretion system or its translocated effectors, as well as other secreted proteins implicated in pathogenesis. Here, we show that X. oryzae pv. oryzae growth in planta or in HrpX-inducing XOM2 media resulted in HrpX-dependent transcription of the raxX and raxST genes that control production of the RaxX sulfopeptide, exported through a type I secretion system. The RaxX protein is required for activation of XA21-mediated immunity in Xa21(+) rice lines. We identified potential plant-inducible promoter elements upstream of the likely 5' ends of the raxX and raxST transcripts. Deletions and nucleotide substitutions confirmed that these elements are required for HrpX-dependent expression of raxX and raxST. We conclude that raxX-raxST gene expression is induced by HrpX during growth in planta and, therefore, is coordinately expressed with other genes required for pathogenesis.