Genetic and molecular requirements for function of the Pto/Prf effector recognition complex in tomato and Nicotiana benthamiana
Genetic and molecular requirements for function of the Pto/Prf effector recognition complex in tomato and Nicotiana benthamiana
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DOI：
10.1111/j.1365-313x.2007.03199.x
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发表时间：
2007-09-01
期刊：
影响因子：
7.2
通讯作者：
Rathjen, John P.
中科院分区：
文献类型：
--
作者：
Balmuth, Alexi;Rathjen, John P.
番茄（Solanum lycopersicum）的Pto基因能够特异性识别不相关的细菌效应蛋白AvrPto和AvrPtoB。Pto位于与核苷酸结合位点-富含亮氨酸的重复蛋白Prf组成的分子复合体中。对于两种效应器的特定识别，Prf是绝对需要的。通过稳定的转基因株系，我们发现Pto基因组启动子在易感番茄中的表达足以补充丁香假单胞菌pv的识别。表达avrPto或avrPtoB的番茄（Pst）细菌。特异性免疫绝对需要Pto激酶活性。Pto n -肉豆肉酰化突变体Pto （G2A）的表达可以识别Pst (avrPtoB)，但不能识别Pst (avrPto)，尽管这些品系的细菌生长介于抗性和易感品系之间。pto（G2A）的过表达补充了avrPto的识别。过表达野生型Pto的转基因番茄植株表现出组成型生长表型，但在过表达Pto的品系中没有这些表型（G2A）。因此，Pto肉豆蔻酰化是番茄中效应识别的一个定量因子，但对于过表达表型是绝对必需的。Pto在异种benthamiana中的原生表达并未使其对紫丁香疫病产生抗性。烟草（Pta）表达avrPto或avrPtoB，但识别这两种效应是由Prf共表达补充。因此，仅由Pto在benthamiana中赋予的特异性抗性是过度表达的人工产物。最后，无论Prf是否存在，pto（G2A）都不能在benthamiana中识别avrPto或avrPtoB。因此，在benthamiana中，Prf的共表达补充了正常Pto功能的许多方面，但不是所有方面。
The Pto gene of tomato (Solanum lycopersicum) confers specific recognition of the unrelated bacterial effector proteins AvrPto and AvrPtoB. Pto resides in a constitutive molecular complex with the nucleotide binding site-leucine rich repeats protein Prf. Prf is absolutely required for specific recognition of both effectors. Here, using stable transgenic lines, we show that expression of Pto from its genomic promoter in susceptible tomatoes was sufficient to complement recognition of Pseudomonas syringae pv. tomato (Pst) bacteria expressing either avrPto or avrPtoB. Pto kinase activity was absolutely required for specific immunity. Expression of the Pto N-myristoylation mutant, pto(G2A), conferred recognition of Pst (avrPtoB), but not Pst (avrPto), although bacterial growth in these lines was intermediate between resistant and susceptible lines. Overexpression of pto(G2A) complemented recognition of avrPto. Transgenic tomato plants overexpressing wild-type Pto exhibited constitutive growth phenotypes, but these were absent in lines overexpressing pto(G2A). Therefore, Pto myristoylation is a quantitative factor for effector recognition in tomato, but is absolutely required for overexpression phenotypes. Native expression of Pto in the heterologous species Nicotiana benthamiana did not confer resistance to P. syringae pv. tabaci (Pta) expressing avrPto or avrPtoB, but recognition of both effectors was complemented by Prf co-expression. Thus, specific resistance conferred solely by Pto in N. benthamiana is an artefact of overexpression. Finally, pto(G2A) did not confer recognition of either avrPto or avrPtoB in N. benthamiana, regardless of the presence of Prf. Thus, co-expression of Prf in N. benthamiana complements many but not all aspects of normal Pto function.