Regulation Involved in Colonization of Intercellular Spaces of Host Plants in Ralstonia solanacearum.
Regulation Involved in Colonization of Intercellular Spaces of Host Plants in Ralstonia solanacearum.
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DOI：
10.3389/fpls.2017.00967
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发表时间：
2017
影响因子：
5.6
通讯作者：
Kai K
中科院分区：
文献类型：
--
作者：
Hikichi Y;Mori Y;Ishikawa S;Hayashi K;Ohnishi K;Kiba A;Kai K
一种土传细菌青枯雷尔氏菌（Ralstonia solanacearum）侵入植物根部，首先定殖于根部的细胞间隙，并最终进入木质部导管，在那里它以高水平复制，导致萎蔫症状。侵入细胞间隙后，R.青枯菌菌株OE 1 -1附着于宿主细胞并表达编码III型分泌系统（T3 SS）组分的hrp基因。然后OE 1 -1构建T3 SS并将效应子分泌到宿主细胞中，诱导编码磷脂酸磷酸酶的宿主基因的表达。这导致抑制植物先天免疫。然后，OE 1 -1在宿主细胞上生长，诱导群体感应（QS）。QS有助于调节OE 1 -1在细胞间隙的定殖，包括在宿主细胞上形成蘑菇型生物膜，从而导致其毒力。R.青枯菌菌株AW 1和K60产生3-羟基棕榈酸甲酯（3-OH PAME）作为QS信号。甲基转移酶PhcB合成3-OH PAME。当3-OH PAME达到阈值水平时，它增加组氨酸激酶PhcS磷酸化反应调节剂PhcR的能力。这导致功能性PhcA（全球毒力调节因子）水平升高。另一方面，菌株OE 1 -1和GMI 1000产生3-羟基肉豆蔻酸甲酯（3-OH MAME）作为QS信号。在R.青枯菌菌株中，推测的PhcB和PhcS氨基酸序列与QS信号的产生有关。R.青枯菌产生芳基-呋喃酮次级代谢物，即ralfuranones，其是细胞外分泌的，并且是其毒力所需的，依赖于QS。有趣的是，ralfuranones影响QS反馈回路。综上所述，通过ralfuranones整合信号影响QS，有助于病原体毒力。
A soil-borne bacterium Ralstonia solanacearum invading plant roots first colonizes the intercellular spaces of the root, and eventually enters xylem vessels, where it replicates at high levels leading to wilting symptoms. After invasion into intercellular spaces, R. solanacearum strain OE1-1 attaches to host cells and expression of the hrp genes encoding components of the type III secretion system (T3SS). OE1-1 then constructs T3SS and secrets effectors into host cells, inducing expression of the host gene encoding phosphatidic acid phosphatase. This leads to suppressing plant innate immunity. Then, OE1-1 grows on host cells, inducing quorum sensing (QS). The QS contributes to regulation of OE1-1 colonization of intercellular spaces including mushroom-type biofilm formation on host cells, leading to its virulence. R. solanacearum strains AW1 and K60 produce methyl 3-hydroxypalmitate (3-OH PAME) as a QS signal. The methyltransferase PhcB synthesizes 3-OH PAME. When 3-OH PAME reaches a threshold level, it increases the ability of the histidine kinase PhcS to phosphorylate the response regulator PhcR. This results in elevated levels of functional PhcA, the global virulence regulator. On the other hand, strains OE1-1 and GMI1000 produce methyl 3-hydroxymyristate (3-OH MAME) as a QS signal. Among R. solanacearum strains, the deduced PhcB and PhcS amino acid sequences are related to the production of QS signals. R. solanacearum produces aryl-furanone secondary metabolites, ralfuranones, which are extracellularly secreted and required for its virulence, dependent on the QS. Interestingly, ralfuranones affect the QS feedback loop. Taken together, integrated signaling via ralfuranones influences the QS, contributing to pathogen virulence.