Iavicoli Annalisa, Boutet Emmanuel, Buchala Antony, Métraux Jean-Pierre
Département de Biologie, Unité Biologie végétale, Université de Fribourg, ch. du musée 10, 1700 Fribourg, Switzerland.
Mol Plant Microbe Interact. 2003 Oct;16(10):851-8. doi: 10.1094/MPMI.2003.16.10.851.
Root inoculation of Arabidopsis thaliana ecotype Columbia with Pseudomonas fluorescens CHA0r partially protected leaves from the oomycete Peronospora parasitica. The molecular determinants of Pseudomonas fluorescens CHA0r for this induced systemic resistance (ISR) were investigated, using mutants derived from strain CHA0: CHA400 (pyoverdine deficient), CHA805 (exoprotease deficient), CHA77 (HCN deficient), CHA660 (pyoluteorin deficient), CHA631 (2,4-diacetylphloroglucinol [DAPG] deficient), and CHA89 (HCN, DAPG- and pyoluteorin deficient). Only mutations interfering with DAPG production led to a significant decrease in ISR to Peronospora parasitica. Thus, DAPG production in Pseudomonas fluorescens is required for the induction of ISR to Peronospora parasitica. DAPG is known for its antibiotic activity; however, our data indicate that one action of DAPG could be due to an effect on the physiology of the plant. DAPG at 10 to 100 microM applied to roots of Arabidopsis mimicked the ISR effect. CHA0r-mediated ISR was also tested in various Arabidopsis mutants and transgenic plants: NahG (transgenic line degrading salicylic acid [SA]), sid2-1 (nonproducing SA), npr1-1 (non-expressing NPR1 protein), jar1-1 (insensitive to jasmonic acid and methyl jasmonic acid), ein2-1 (insensitive to ethylene), etr1-1 (insensitive to ethylene), eir1-1 (insensitive to ethylene in roots), and pad2-1 (phytoalexin deficient). Only jar1-1, eir1-1, and npr1-1 mutants were unable to undergo ISR. Sensitivity to jasmonic acid and functional NPR1 and EIR1 proteins were required for full expression of CHA0r-mediated ISR. The requirements for ISR observed in this study in Peronospora parasitica induced by Pseudomonas fluorescens CHA0r only partially overlap with those published so far for Peronospora parasitica, indicating a great degree of flexibility in the molecular processes leading to ISR.
用荧光假单胞菌CHA0r对拟南芥生态型哥伦比亚进行根部接种，可部分保护叶片免受寄生霜霉这种卵菌的侵害。利用源自CHA0菌株的突变体研究了荧光假单胞菌CHA0r诱导系统抗性（ISR）的分子决定因素：CHA400（缺乏绿脓菌素）、CHA805（缺乏胞外蛋白酶）、CHA77（缺乏HCN）、CHA660（缺乏绿胶霉素）、CHA631（缺乏2,4-二乙酰基间苯三酚[DAPG]）以及CHA89（缺乏HCN、DAPG和绿胶霉素）。只有干扰DAPG产生的突变会导致对寄生霜霉的ISR显著降低。因此，荧光假单胞菌产生DAPG是诱导对寄生霜霉的ISR所必需的。DAPG以其抗菌活性而闻名；然而，我们的数据表明DAPG的一种作用可能是由于对植物生理学的影响。将10至100微摩尔的DAPG施用于拟南芥根部可模拟ISR效应。还在各种拟南芥突变体和转基因植物中测试了CHA0r介导的ISR：NahG（降解水杨酸[SA]的转基因株系）、sid2-1（不产生SA）、npr1-1（不表达NPR1蛋白）、jar1-1（对茉莉酸和茉莉酸甲酯不敏感）、ein2-1（对乙烯不敏感）、etr1-1（对乙烯不敏感）、eir1-1（根部对乙烯不敏感）以及pad2-1（缺乏植保素）。只有jar1-1、eir1-1和npr1-1突变体无法产生ISR。对茉莉酸的敏感性以及功能性NPR1和EIR1蛋白是CHA0r介导的ISR充分表达所必需的。本研究中观察到的荧光假单胞菌CHA0r诱导的寄生霜霉ISR的要求与迄今为止已发表的寄生霜霉的要求仅部分重叠，这表明导致ISR的分子过程具有很大的灵活性。
