Song Jong Tae, Lu Hua, McDowell John M, Greenberg Jean T
Department of Molecular Genetics and Cell Biology, Erman Biology Center, The University of Chicago, 1103 East 57th Street, Chicago, IL 60637, USA.
Plant J. 2004 Oct;40(2):200-12. doi: 10.1111/j.1365-313X.2004.02200.x.
The Arabidopsis thaliana agd2-like defense response protein1 (ald1) mutant was previously found to be hypersusceptible to the virulent bacterial pathogen Pseudomonas syringae and had reduced accumulation of the defense signal salicylic acid (SA). ALD1 was shown to possess aminotransferase activity in vitro, suggesting it generates an amino acid-derived defense signal. We now find ALD1 to be a key defense component that acts in multiple contexts and partially requires the PHYTOALEXIN DEFICIENT4 (PAD4) defense regulatory gene for its expression in response to infection. ald1 plants have increased susceptibility to avirulent P. syringae strains, are unable to activate systemic acquired resistance and are compromised for resistance to the oomycete pathogen Peronospora parasitica in mutants with constitutively active defenses. ALD1 and PAD4 can act additively to control SA, PATHOGENESIS RELATED GENE1 (PR1) transcript and camalexin (an antimicrobial metabolite) accumulation as well as disease resistance. Finally, ALD1 and PAD4 can mutually affect each other's expression in a constitutive defense mutant, suggesting that these two genes can act in a signal amplification loop.
拟南芥类agd2防御反应蛋白1（ald1）突变体先前被发现对毒性细菌病原体丁香假单胞菌高度敏感，且防御信号水杨酸（SA）的积累减少。ALD1在体外显示具有转氨酶活性，表明它能产生一种氨基酸衍生的防御信号。我们现在发现ALD1是一个关键的防御成分，在多种情况下发挥作用，并且在响应感染时其表达部分需要植物抗毒素缺陷4（PAD4）防御调节基因。ald1植物对无毒丁香假单胞菌菌株的易感性增加，无法激活系统获得性抗性，并且在具有组成型活性防御的突变体中对卵菌病原体寄生霜霉的抗性受损。ALD1和PAD4可以协同作用来控制SA、病程相关基因1（PR1）转录本和camalexin（一种抗菌代谢物）的积累以及抗病性。最后，在组成型防御突变体中，ALD1和PAD4可以相互影响彼此的表达，表明这两个基因可以在信号放大环中发挥作用。
