Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA.
Mol Plant Microbe Interact. 2010 Jun;23(6):727-39. doi: 10.1094/MPMI-23-6-0727.
The type III secretion system (T3SS) of Pseudomonas syringae translocates into plant cells multiple effectors that suppress pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). P. syringae pv. tomato DC3000 no longer delivers the T3SS translocation reporter AvrPto-Cya in Nicotiana benthamiana leaf tissue in which PTI was induced by prior inoculation with P. fluorescens(pLN18). Cosmid pLN18 expresses the T3SS system of P. syringae pv. syringae 61 but lacks the hopA1(Psy61) effector gene. P. fluorescens(pLN18) expressing HrpH(PtoDC3000) or HopP1(PtoDC3000), two T3SS-associated putative lytic transglycosylases, suppresses PTI, based on multiple assays involving DC3000 challenge inoculum (AvrPto-Cya translocation, hypersensitive response elicitation, and colony development in planta) or on plant responses (vascular dye uptake or callose deposition). Analysis of additional mutations in pHIR11 derivatives revealed that the pLN18-encoded T3SS elicits a higher level of reactive oxygen species (ROS) than does P. fluorescens without a T3SS, that enhanced ROS production is dependent on the HrpK1 translocator, and that HopA1(Psy61) suppresses ROS elicitation attributable to both the P. fluorescens PAMPs and the presence of a functional T3SS.
丁香假单胞菌的 III 型分泌系统（T3SS）将多个效应子转运到植物细胞中，这些效应子抑制与病原体相关的分子模式（PAMP）触发的免疫（PTI）。在之前用荧光假单胞菌（pLN18）接种诱导 PTI 的烟草原生质体中，丁香假单胞菌 pv.番茄 DC3000 不再输送 T3SS 转运报告蛋白 AvrPto-Cya。cosmid pLN18 表达了丁香假单胞菌 pv.丁香 61 的 T3SS 系统，但缺乏 hopA1(Psy61)效应基因。表达 HrpH(PtoDC3000)或 HopP1(PtoDC3000)的荧光假单胞菌（pLN18），这两种 T3SS 相关的假定溶葡糖苷酶，抑制了 PTI，这基于涉及 DC3000 挑战接种物（AvrPto-Cya 转运、过敏反应诱导和植物体内菌落发育）或植物反应（血管染料摄取或胼胝质沉积）的多个测定。对 pHIR11 衍生物的其他突变分析表明，与没有 T3SS 的荧光假单胞菌相比，pLN18 编码的 T3SS 引发了更高水平的活性氧（ROS），增强的 ROS 产生依赖于 HrpK1 转运器，HopA1(Psy61)抑制了归因于荧光假单胞菌 PAMPs 和功能 T3SS 存在的 ROS 诱导。
