Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka 1-1-1, Okayama 700-8530, Japan.
Mol Plant Pathol. 2011 Sep;12(7):709-14. doi: 10.1111/j.1364-3703.2011.00705.x. Epub 2011 Feb 21.
The HrpZ harpin of Pseudomonas syringae is known to induce a hypersensitive response (HR) in some plants. In P. syringae pv. tabaci (Pta), the harpin gene hrpZ has been spontaneously disrupted by an internal deletion in its open reading frame and a frame shift. The loss of the ability of the recombinant harpin polypeptide of Pta to induce HR despite the high sensitivity of tobacco plants to harpin led us to investigate the meaning of the disrupted hrpZ gene in the virulence of Pta 6605. The hrpZ gene from P. syringae pv. pisi was introduced into wild-type (WT) Pta. The hrpZ-complemented Pta secreted harpin into the culture medium, but failed to cause disease symptoms by both infiltration and spray inoculation. Inoculation with the hrpZ-complemented Pta induced defence responses in tobacco plants, whereas the defence responses of tobacco plants were not prominent on inoculation with WT Pta. These results indicate that an ancestor of Pta might have disrupted hrpZ by an internal deletion to evade plant defences and confer the ability to cause disease in tobacco plants.
丁香假单胞菌的 HrpZ 菌毛已知会在某些植物中引发过敏反应 (HR)。在丁香假单胞菌 pv. 番茄 (Pta) 中，hrpZ 基因的开放阅读框内发生了自发缺失和移码突变，导致重组 Pta 菌毛多肽丧失了诱导 HR 的能力，尽管烟草植物对菌毛高度敏感。这促使我们研究 Pta 6605 毒力中缺失的 hrpZ 基因的意义。从豌豆细菌性斑点病菌中引入了 hrpZ 基因到野生型 (WT) Pta 中。hrpZ 互补的 Pta 将菌毛分泌到培养基中，但通过浸润和喷雾接种均未能引起病症。用 hrpZ 互补的 Pta 接种会诱导烟草植物的防御反应，而用 WT Pta 接种则不会引起烟草植物的防御反应明显。这些结果表明，Pta 的一个祖先可能通过内部缺失破坏了 hrpZ，以逃避植物防御，并赋予在烟草植物中引起疾病的能力。
