Singh Archana, Kumar Amit, Hartley Susan, Singh Indrakant Kumar
Department of Botany, Hansraj College, University of Delhi, Delhi, India.
Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, UK.
J Exp Bot. 2020 Dec 2;71(21):6730-6743. doi: 10.1093/jxb/eraa300.
Plants protect themselves against pest attack utilizing both direct and indirect modes of defense. The direct mode of defense includes morphological, biochemical, and molecular barriers that affect feeding, growth, and survival of herbivores whereas the indirect mode of defense includes release of a blend of volatiles that attract natural enemies of the pests. Both of these strategies adopted by plants are reinforced if the plants are supplied with one of the most abundant metalloids, silicon (Si). Plants absorb Si as silicic acid (Si(OH)4) and accumulate it as phytoliths, which strengthens their physical defense. This deposition of Si in plant tissue is up-regulated upon pest attack. Further, Si deposited in the apoplast, suppresses pest effector molecules. Additionally, Si up-regulates the expression of defense-related genes and proteins and their activity and enhances the accumulation of secondary metabolites, boosting induced molecular and biochemical defenses. Moreover, Si plays a crucial role in phytohormone-mediated direct and indirect defense mechanisms. It is also involved in the reduction of harmful effects of oxidative stress resulting from herbivory by accelerating the scavenging process. Despite increasing evidence of its multiple roles in defense against pests, the practical implications of Si for crop protection have received less attention. Here, we highlight recent developments in Si-mediated improved plant resistance against pests and its significance for future use in crop improvement.
植物利用直接和间接防御模式来保护自身免受害虫侵害。直接防御模式包括影响食草动物取食、生长和生存的形态、生化和分子屏障，而间接防御模式包括释放吸引害虫天敌的挥发性混合物。如果给植物供应最丰富的类金属元素之一硅（Si），那么植物所采用的这两种策略都会得到加强。植物以硅酸（Si(OH)4）形式吸收硅，并将其积累为植硅体，从而增强其物理防御。硅在植物组织中的这种沉积在受到害虫攻击时会上调。此外，沉积在质外体中的硅会抑制害虫效应分子。此外，硅上调防御相关基因和蛋白质的表达及其活性，并增强次生代谢产物的积累，从而增强诱导的分子和生化防御。此外，硅在植物激素介导的直接和间接防御机制中起着关键作用。它还通过加速清除过程来减少食草动物引起的氧化应激的有害影响。尽管越来越多的证据表明硅在抵御害虫方面具有多种作用，但硅在作物保护中的实际应用却较少受到关注。在此，我们重点介绍硅介导的植物抗虫性改善方面的最新进展及其在未来作物改良中的意义。
