番茄木虱取食对含Mi-1.2番茄抗氧化酶活性及防御反应相关基因表达的影响

Effects of Tomato Psyllid Infestation on Activity of Anti-oxidant Enzymes and Expression Levels of Defense Response Related Genes in the Tomato Carrying Resistance Gene Mi-1.2

Mi-1.2基因编码CC-NBS-LRR家族抗病蛋白,对线虫及刺吸式昆虫具有广谱抗性。以番茄木虱和携带Mi-1.2基因的番茄品系‘Motelle’作为研究体系,研究番茄木虱取食对番茄叶片抗氧化酶活性及防御反应相关基因表达的影响。结果表明:番茄木虱的取食显著提高了番茄叶片抗氧化酶POD、CAT、APX等的活性,同时诱导Mi-1.2基因表达;番茄木虱的取食上调SA合成有关基因PAL、SA信号途径标志基因PR-1(P4)及与Mi-1.2功能相关基因WRKY70、WRKY72a、WRKY72b的表达。JA/systemin信号途径和伤害有关的Pin II、TPI-1、PR-6、PR-7、PR-5等及Prosystemin编码基因Psy的表达未发生变化;JA合成途径相关酶编码基因AOS2、Lox D下调表达,AOC的表达没有变化。SA信号途径可能参与Mi-1.2介导的番茄对于刺吸式昆虫番茄木虱的防御反应。另外,Mi-1.2的RNAi沉默不会改变上述基因的m RNA水平,说明Mi-1.2基因产物对这些基因的表达无调控作用。

Mi-1.2 is a CC-NBS-LRR protein encoding gene in tomato that confers broad-spectrum resistance toward nematode and piercing-sucking insects such as aphid,whitefly and psyllid.In this study,we investigated the mechanism of Mi-1.2 resistance toward tomato psyllid by measuring the activity of anti-oxidant enzymes and transcript levels of defense response related genes in resistant tomato cultivar＇Motelle＇challenged with tomato psyllid infestation.Feeding of tomato psyllid elevated the activity of protective enzymes POD,CAT and APX,and also induced the expression of the gene coding for PAL,a key enzyme in SA synthesis,SA signaling marker gene PR-1 and also three WRKY family genes required for Mi-1.2 mediated defense response.Mi-1.2 itself is also upregulated by tomato psyllid feeding.Expression level of JA/systemin signaling pathway related genes such as Pin II,TPI-1,PR-6,PR-7,PR-5 and prosystemin encoding gene Psy did not change,while the expression of JA synthesis related genes AOS2 and Lox D was repressed by tomato psyllid infestation.The results indicated that SA signaling pathway is involved in Mi-1.2 mediated tomato resistance against piercing-sucking insect tomato psyllid.Expression of those genes mentioned above was not altered by RNAi knockdown of Mi-1.2,suggesting that Mi-1.2 has no regulatory role on the expression of these genes.