Unidad de Biotecnología e Ingeniería Genética de Plantas, (Cinvestav-Unidad Irapuato), Km 9.6 del Libramiento Norte Carretera Irapuato-León, Apartado Postal 629, C.P. 36821, Irapuato, Gto., Mexico.
Planta. 2011 Mar;233(3):507-21. doi: 10.1007/s00425-010-1314-7. Epub 2010 Nov 23.
Transgenic tobacco plants capable of over-expressing Xenopus PPARα (xPPARα), a transcription factor known to be required for peroxisome proliferation in animals, were recently generated. These plants (herewith referred to as PPAR-OE) were found to have increased peroxisome abundance, higher peroxisomal acyl-CoA oxidase and catalase activity and modified fatty acid metabolism. Further characterization of PPAR-OE plants revealed a higher susceptibility to virulent and a partial loss of resistance to avirulent Pseudomonas syringae pathogens, whereas the basal resistance response remained unaffected. Biochemical- and defense-related gene expression analyses showed that increased susceptibility to bacterial invasion coincided with the generalized reduction in H(2)O(2) and salicylic acid (SA) levels observed within the first 24 h of bacterial contact. Decreased H(2)O(2) levels were correlated with modified activity levels of catalase and other antioxidant enzymes. A correspondence between a rapid (within 1-24 hpi; ACCO and AOC) and sustained increase (up to 6 days pi; ACCO) in the expression levels of ethylene (ACCO) and jasmonic acid (AOC) biosynthetic genes and a higher susceptibility to virulent bacterial invasion was also observed in PPAR-OE plants. Conversely, no apparent differences in the short- and/or long-term expression levels of markers for the hypersensitive-response, oxidative burst and systemic-acquired resistance were observed between wild type and PPAR-OE plants. The results suggest that peroxisome proliferation could lead to increased susceptibility to bacterial pathogens in tobacco by altering the redox balance of the plant and the expression pattern of key defense signaling pathway genes.
最近生成了能够过表达 Xenopus PPARα（xPPARα）的转基因烟草植物，xPPARα 是一种已知在动物中过氧化物酶体增殖所必需的转录因子。这些植物（以下简称 PPAR-OE）被发现过氧化物酶体丰度增加，过氧化物酶体酰基辅酶 A 氧化酶和过氧化氢酶活性更高，以及脂肪酸代谢发生改变。对 PPAR-OE 植物的进一步表征表明，它们对毒性更强的病原体的敏感性增加，对非毒性 Pseudomonas syringae 病原体的部分抗性丧失，而基础抗性反应不受影响。生化和防御相关基因表达分析表明，对细菌入侵的敏感性增加与在接触细菌后的前 24 小时内观察到的 H2O2 和水杨酸（SA）水平的普遍降低相吻合。H2O2 水平的降低与过氧化氢酶和其他抗氧化酶的活性水平改变有关。在 PPAR-OE 植物中，还观察到乙烯（ACCO）和茉莉酸（AOC）生物合成基因的快速（1-24 hpi；ACCO 和 AOC）和持续（高达 6 天 pi；ACCO）表达水平的对应关系，以及对毒性更强的细菌入侵的敏感性增加。相反，在野生型和 PPAR-OE 植物之间，没有观察到与过敏反应、氧化爆发和系统获得性抗性相关的标记物的短期和/或长期表达水平的明显差异。结果表明，过氧化物酶体增殖可能通过改变植物的氧化还原平衡和关键防御信号通路基因的表达模式，导致烟草对细菌病原体的敏感性增加。
