Maldonado Ana M, Doerner Peter, Dixon Richard A, Lamb Chris J, Cameron Robin K
The Salk Institute, La Jolla, California 92037, USA.
Nature. 2002 Sep 26;419(6905):399-403. doi: 10.1038/nature00962.
Localized attack by a necrotizing pathogen induces systemic acquired resistance (SAR) to subsequent attack by a broad range of normally virulent pathogens. Salicylic acid accumulation is required for activation of local defenses, such as pathogenesis-related protein accumulation, at the initial site of attack, and for subsequent expression of SAR upon secondary, distant challenge. Although salicylic acid moves through the plant, it is apparently not an essential mobile signal. We screened Agrobacterium tumefaciens transfer DNA (tDNA) tagged lines of Arabidopsis thaliana for mutants specifically compromized in SAR. Here we show that Defective in induced resistance 1-1 (dir1-1) exhibits wild-type local resistance to avirulent and virulent Pseudomonas syringae, but that pathogenesis-related gene expression is abolished in uninoculated distant leaves and dir1-1 fails to develop SAR to virulent Pseudomonas or Peronospora parasitica. Petiole exudate experiments indicate that dir1-1 is defective in the production or transmission from the inoculated leaf of an essential mobile signal. DIR1 encodes a putative apoplastic lipid transfer protein and we propose that DIR1 interacts with a lipid-derived molecule to promote long distance signalling.
坏死性病原体的局部侵染会诱导植物产生系统获得性抗性（SAR），从而抵御随后多种通常具有毒性的病原体的侵染。水杨酸的积累对于在侵染初始部位激活局部防御（如病程相关蛋白的积累）以及在二次远距离侵染时随后表达SAR是必需的。尽管水杨酸在植物体内移动，但它显然不是必需的移动信号。我们筛选了拟南芥根癌农杆菌转移DNA（tDNA）标签系，以寻找在SAR中存在特异性缺陷的突变体。在此我们表明，诱导抗性缺陷1-1（dir1-1）对无毒和有毒的丁香假单胞菌表现出野生型局部抗性，但在未接种的远距离叶片中病程相关基因的表达被消除，并且dir1-1不能对有毒的丁香假单胞菌或寄生霜霉产生SAR。叶柄渗出液实验表明，dir1-1在产生或从接种叶片传递必需的移动信号方面存在缺陷。DIR1编码一种假定的质外体脂质转运蛋白，我们提出DIR1与一种脂质衍生分子相互作用以促进长距离信号传导。
