Agrocampus Ouest, UMR1349 IGEPP, 35000 Rennes, France.
Plant Physiol Biochem. 2012 Aug;57:23-31. doi: 10.1016/j.plaphy.2012.05.006. Epub 2012 May 15.
Physiological and molecular mechanisms underlying quantitative resistance of plants to pathogens are still poorly understood, but could depend upon differences in the intensity or timing of general defense responses. This may be the case for the biosynthesis of phenolics which are known to increase after elicitation by pathogens. We thus tested the hypothesis that differences in quantitative resistance were related to differential induction of phenolics by pathogen-derived elicitors. Five potato cultivars (Solanum tuberosum, L.) spanning a range of quantitative resistance were treated with a concentrated culture filtrate (CCF) of Phytophthora infestans or purified lipopolysaccharides (LPS) from Pectobacterium atrosepticum. The kinetic of phenolics accumulation was followed and a set of typical phenolics was identified: chlorogenic acid, phenolamides and flavonols including rutin (quercetin-3-O-rutinoside) and nicotiflorin (kaempferol-3-O-rutinoside). Our results showed that CCF but not LPS induced differential accumulation of major phenolics among cultivars. Total phenolics were related with resistance to P. atrosepticum but not to P. infestans. However, nicotiflorin was inversely related with resistance to both pathogens. Rutin, but not nicotiflorin, inhibited pathogen growth in vitro at physiological concentrations. These data therefore suggest that (i) several phenolics are candidate markers for quantitative resistance in potato, (ii) some of these are pathogen specific although they are produced by a general defense pathway, (iii) resistance marker molecules do not necessarily have antimicrobial activity, and (iv) the final content of these target molecules-either constitutive or induced-is a better predictor of resistance than their inducibility by pathogen elicitors.
植物对病原体定量抗性的生理和分子机制仍知之甚少，但可能取决于一般防御反应的强度或时间的差异。这种情况可能适用于酚类物质的生物合成，已知这些物质在受到病原体激发后会增加。因此，我们检验了以下假设：定量抗性的差异与病原体衍生的激发子对酚类物质的差异诱导有关。我们用致病疫霉浓缩培养滤液（CCF）或果胶杆菌脂多糖（LPS）处理了五个马铃薯品种（茄属），这些品种的定量抗性范围很广。跟踪了酚类物质积累的动力学，并鉴定了一组典型的酚类物质：绿原酸、酚酰胺和类黄酮，包括芦丁（槲皮素-3-O-芸香糖苷）和烟碱素（山奈酚-3-O-芸香糖苷）。我们的结果表明，CCF 而非 LPS 诱导了品种之间主要酚类物质的差异积累。总酚类物质与对果胶杆菌的抗性有关，但与致病疫霉无关。然而，烟碱素与两种病原体的抗性呈负相关。芦丁（但不是烟碱素）在生理浓度下抑制病原体在体外的生长。因此，这些数据表明：（i）几种酚类物质是马铃薯定量抗性的候选标志物，（ii）其中一些是病原体特异性的，尽管它们是通过一般防御途径产生的，（iii）抗性标记分子不一定具有抗菌活性，（iv）这些靶分子的最终含量（无论是组成型还是诱导型）比它们对病原体激发子的诱导能力更好地预测抗性。
