Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA.
Mol Plant Microbe Interact. 2011 Jul;24(7):773-86. doi: 10.1094/MPMI-06-10-0143.
The broad-host-range bacterial soft rot pathogen Pectobacterium carotovorum causes a DspE/F-dependent plant cell death on Nicotiana benthamiana within 24 h postinoculation (hpi) followed by leaf maceration within 48 hpi. P. carotovorum strains with mutations in type III secretion system (T3SS) regulatory and structural genes, including the dspE/F operon, did not cause hypersensitive response (HR)-like cell death and or leaf maceration. A strain with a mutation in the type II secretion system caused HR-like plant cell death but no maceration. P. carotovorum was unable to impede callose deposition in N. benthamiana leaves, suggesting that P. carotovorum does not suppress this basal immunity function. Within 24 hpi, there was callose deposition along leaf veins and examination showed that the pathogen cells were localized along the veins. To further examine HR-like plant cell death induced by P. carotovorum, gene expression profiles in N. benthamiana leaves inoculated with wild-type and mutant P. carotovorum and Pseudomonas syringae strains were compared. The N. benthamiana gene expression profile of leaves infiltrated with Pectobacterium carotovorum was similar to leaves infiltrated with a Pseudomonas syringae T3SS mutant. These data support a model where Pectobacterium carotovorum uses the T3SS to induce plant cell death in order to promote leaf maceration rather than to suppress plant immunity.
广谱细菌软腐病原菌果胶杆菌（Pectobacterium carotovorum）在接种后 24 小时内（hpi）引起拟南芥叶片细胞死亡，并在 48 hpi 内导致叶片软化。在 III 型分泌系统（T3SS）调节和结构基因（包括 dspE/F 操纵子）发生突变的果胶杆菌菌株不会引起过敏性细胞死亡或叶片软化。II 型分泌系统发生突变的菌株会引起类似 HR 的植物细胞死亡，但不会导致叶片软化。果胶杆菌不能阻止在拟南芥叶片中几丁质的沉积，表明果胶杆菌不会抑制这种基础免疫功能。在 24 hpi 时，沿叶脉有几丁质沉积，检查表明病原体细胞定位于叶脉处。为了进一步研究果胶杆菌诱导的类似 HR 的植物细胞死亡，比较了接种野生型和突变型果胶杆菌和丁香假单胞菌菌株的拟南芥叶片中的基因表达谱。用果胶杆菌浸润的拟南芥叶片的基因表达谱与浸润丁香假单胞菌 T3SS 突变体的叶片相似。这些数据支持果胶杆菌利用 T3SS 诱导植物细胞死亡以促进叶片软化而不是抑制植物免疫的模型。
