昆虫对植物蛋白酶抑制素的诱导及适应机制

Plant proteinase inhibitor: induction and adaptation in insects

植物蛋白酶抑制素是植物重要的防御物质之一 ,一般是分子量较小的多肽或蛋白质 ,能够与昆虫消化道内的蛋白酶形成复合物 ,阻断或削弱蛋白酶对食物中蛋白的水解 ,使昆虫厌食或消化不良而致死。植物蛋白酶抑制素在植物体内一般是诱导表达的 ,昆虫取食危害后 ,导致某些植物在伤口产生一种寡聚糖信息素———蛋白酶抑制素诱导因子 ,蛋白酶抑制素诱导因子诱导叶片局部产生植物蛋白酶抑制素 ,并刺激产生信号物质系统肽 ,通过十八烷酸途径在一系列酶的作用下产生茉莉酸 ,茉莉酸与受体结合 ,活化植物蛋白酶抑制素基因。昆虫在长期取食植物蛋白酶抑制素后会在生理及行为上产生适应性而导致不敏感 ,适应方式主要包括 :(1)改变肠道蛋白酶对蛋白酶抑制素的敏感性 ;(2 )水解蛋白酶抑制素 ;(3)过量取食及干扰产生蛋白酶抑制素的信号通道。由于昆虫能够对植物蛋白酶抑制素产生适应 。

The induction of plant proteinase inhibitor (PPI ) by insects has been the subject of considerable research interest. After being attacked by insects some plants can release proteinase inhibitor inducing factor (PIIF) at the site of injury. PIIF stimulates the production of systemin which activates the synthesis of jasmonic acid through the octadecanoid pathway. Jasmonic acid activates the PPI gene causing new PPI to be synthesized. On the other hand, insects can develop adaptations to PPI through the following mechanisms: (1) changing the sensitivity of the insect proteinase to PPI; (2)decomposing PPIs; (3) feeding excessively and interfering with the PPI production signal pathway. The signal molecules and their functions in inducing PPI production and the adaptation to PPI by insects are reviewed.