硅对植物抗虫性的影响及其机制

硅不是植物必需营养元素,但硅在提高植物对一系列非生物和生物胁迫的抗性方面都具有重要作用。综述了硅对植物抗虫性的影响及其机制。在多数植物中,增施硅肥可增强其抗虫性;所增强的抗性与硅肥种类和施用方式之间存在关系。植物组织中沉积的硅可增加其硬度和耐磨度,降低植物可消化性,从而增强植物组成性防御,包括延缓昆虫生长发育、降低繁殖力、减轻植物受害程度;植物体内的硅含量以及硅沉积的位点和排列方式影响组成性防御作用的强度。此外,硅可以调节植物诱导性防御,包括直接防御和间接防御,直接防御涉及增加有毒物质含量、产生局部过敏反应或系统获得抗性、产生有毒化合物和防御蛋白,从而延缓昆虫发育;间接防御主要通过释放挥发性化合物吸引植食性昆虫的捕食性和寄生性天敌而导致植食性昆虫种群下降。

Role of silicon in regulating plant resistance to insect herbivores

Although silicon (Si) is not an essential element for the majority of plant species, it plays an important role in plant resistance to a range of abiotic and biotic stresses. In this paper, we review the role of Si in regulating host plant resistance to herbivorous insects. Si can enhance resistance to insect herbivores in the majority of plant species, which depends on the sources and the application modes of Si fertilizer. Si can enhance constitutive resistance of plants to herbivorous insects by increasing hardness and abrasiveness of plant tissues and/or reducing digestibility. This leads to a reduction in insect growth and reproduction with a concomitant reduction in crop damage. Si content, sediment position and alignment in plants affects the subsequent strength of constitutive resistance. In addition, Si can regulate induced direct plant defenses as well as indirect defenses. Induced direct defense comprises producing toxic substances, producing localized hypersensitive response and systemic acquired resistance, and releasing toxic compounds and defensive proteins, which slow herbivore growth and development. Induced indirect defense is realized through the emission of volatile compounds that attract parasitic and/or predatory natural enemies of the herbivorous insects.