An avrPto/avrPtoB mutant of Pseudomonas syringae pv. tomato DC3000 does not elicit Pto-mediated resistance and is less virulent on tomato
An avrPto/avrPtoB mutant of Pseudomonas syringae pv. tomato DC3000 does not elicit Pto-mediated resistance and is less virulent on tomato
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DOI：
10.1094/mpmi-18-0043
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发表时间：
2005-01-01
影响因子：
3.5
通讯作者：
Martin, GB
中科院分区：
文献类型：
--
作者：
Lin, NC;Martin, GB
AvrPto和AvrPtoB是丁香假单胞菌pv表达的III型效应蛋白。每个效应物都与番茄Pto激酶相互作用，当在含有Pto的番茄叶片中表达时，会引起过敏反应。先前的研究表明，DC3000的avrPto缺失突变体对表达pto的番茄植株保持无毒活性。我们开发了一个DC3000的avrPtoB缺失突变体，发现它在番茄上也保持了pto特异性的无毒。这些观察结果表明，avrPto和avrPtoB都有助于无毒。为了验证这一假设，我们在DC3000中开发了DeltaavrPtoDeltaavrPtoB双突变体。该双突变体能够在表达pto的番茄系上引起疾病。因此，avrPto和avrPtoB是DC3000中唯一引起番茄pto介导的防御反应的无毒基因。将突变体DC3000DeltaavrPto和DC3000DeltaavrPtoB接种到易感番茄叶片上，与野生型DC3000相比，突变体DC3000DeltaavrPto和DC3000DeltaavrPtoB引起的疾病症状略轻，但其生长速度未受影响。然而，DC3000Deltaavr PtoDeltaavrPtoB在易感叶片上的发病症状比单突变体更轻，生长速度也比单突变体慢。结果表明，AvrPto和AvrPtoB对表达pto的番茄具有表型冗余毒力，对番茄易感植株具有加性毒力。
AvrPto and AvrPtoB are type III effector proteins expressed by Pseudomonas syringae pv. tomato strain DC3000, a pathogen of both tomato and Arabidopsis spp. Each effector physically interacts with the tomato Pto kinase and elicits a hypersensitive response when expressed in tomato leaves containing Pto. An avrPto deletion mutant of DC3000 previously was shown to retain avirulence activity on Pto-expressing tomato plants. We developed an avrPtoB deletion mutant of DC3000 and found that it also retains Pto-specific avirulence on tomato. These observations suggested that avrPto and avrPtoB both contribute to avirulence. To test this hypothesis, we developed an DeltaavrPtoDeltaavrPtoB double mutant in DC3000. This double mutant was able to cause disease on a Pto-expressing tomato line. Thus, avrPto and avrPtoB are the only avirulence genes in DC3000 that elicit Pto-mediated defense responses in tomato. When inoculated onto susceptible tomato leaves and compared with wild-type DC3000, the mutants DC3000DeltaavrPto and DC3000DeltaavrPtoB each caused slightly less severe disease symptoms, although their growth rate was unaffected. However, DC3000Deltaavr PtoDeltaavrPtoB caused even less severe disease symptoms than the single mutants and grew more slowly than them on susceptible leaves. Our results indicate that AvrPto and AvrPtoB have phenotypically redundant avirulence activity on Pto-expressing tomato and additive virulence activities on susceptible tomato plants.