西花蓟马取食对菜豆防御基因表达的诱导作用

为探讨菜豆对西花蓟马Frankliniella occidentalis取食的防御反应分子机制， 本实验利用荧光定量PCR（RT-qPCR）研究了西花蓟马取食、 机械损伤及外源水杨酸甲酯（MeSA）和茉莉酸（JA）处理对菜豆叶片防御相关基因（LOX, AOS, PAL及PR-2）相对表达量的影响。结果表明： 脂氧合酶基因（LOX）的相对表达量在外源JA和机械损伤诱导后分别在24 h和48 h时达到最大值， 但与对照相比差异不显著（P>0.05）， 外源MeSA处理后LOX几乎没有表达， 西花蓟马取食后LOX的相对表达量在24 h显著升高， 约为对照的41.9倍， 且明显高于其余3个处理（P<0.05）。不同诱导处理后丙二烯氧化物合成酶基因（AOS）的相对表达量较低， 其中外源MeSA处理后在整个诱导时间内几乎没有表达。苯丙氨酸解氨酶基因（PAL）在机械损伤和外源JA处理后在整个诱导时间内几乎没有表达， 外源MeSA处理后PAL的表达量在24 h时最高， 为对照的1.9倍左右。PAL的相对表达量在遭受蓟马取食诱导后迅速升高， 在24 h时约为CK的4.3倍， 显著高于其他3种处理诱导的（P<0.05）。β-1, 3-葡聚糖酶基因（PR-2）的相对表达量在蓟马取食和外源JA处理的整个诱导时间内受到抑制， 机械损伤诱导后PR-2的表达水平在24 h时有所升高， 之后诱导期间内受到抑制。外源MeSA诱导后菜豆叶片中PR-2的相对表达量在24 h就急剧升高， 达到对照的6.63倍， 且显著高于其余3种处理诱导的（P<0.05）， 但48 h后却几乎检测不到。研究结果提示， 西花蓟马取食不仅能够诱导SA和JA介导的信号传导途径， 且两通路间存在交互作用。

Expression of some defense enzyme genes in kidney bean leaves fed by Frankliniella occidentalis (Thysanoptera: Thripidae)

In order to investigate the molecular mechanisms of defense responses of kidney bean to feeding of the western flower thrips (WFT), Frankliniella occidentalis (Pergande), the expression of defense enzyme genes (LOX, AOS, PAL and PR-2) in kidney bean leaves induced by WFT feeding, mechanical damage, exogenous methyl salicylate (MeSA), and exogenous jasmonic acid (JA), respectively, were detected by real-time quantitative PCR (RT-qPCR). The results showed that the expression level of lipoxygenase gene (LOX) reached the peak at 24 h after JA induction and at 48 h after mechanical damage, respectively, but was not significantly different from the controls (P>0.05). LOX was hardly expressed after kidney bean leaves were treated by MeSA. The relative expression level of LOX was about 41.9 times as high as that of the control at 24 h after WFT feeding and was significantly higher than that in other three treatments (P<0.05). The allene oxide synthase gene (AOS) was expressed at a relatively lower level in different treatments and was barely expressed in the entire time of MeSA induction. The phenylalanine ammonialyase gene (PAL) was scarcely expressed during the induction of mechanical damage and JA, and reached the maximum, and its expression was 1.9 times as high as that of the control at 24 h after MeSA treatment. The expression level of PAL rose rapidly after WFT feeding, and was about 4.3 times as high as that of the control at 24 h, significantly higher than in other three treatments (P<0.05). The expression of β-1,3-glucanase gene (PR-2) was suppressed during the induction of WFT feeding and JA. The expression level of PR-2 increased at 24 h after mechanical damage and then decreased during the induction. The expression level of PR-2 dramatically increased in 24 h after MeSA induction, and was nearly 6.63 times as high as that of the control, significantly higher than that in other three treatments (P<0.05), but hardly expressed after 48 h. The findings suggest that WFT feeding could induce the SA- and JA-mediated signal transduction pathways and there are crosstalks between them.