作 者 ：宁东峰 梁永超
期 刊 ：植物营养与肥料学报 2014年 20卷 5期 页码：1280-1287
关键词：硅；植物；病菌；防御；物理机制；生物化学机制；分子机制；
Keywords:silicon, plant, pathogen, resistance, physical mechanism, biochemical mechanism, molecular mechanism.,
摘 要 ：【目的】硅素营养增强作物对病虫害的防御能力已得到充分证实，但其作用机理至今仍然没有明确。本文对国内外有关硅素营养与作物病害发展的相互关系及相关机理的最新研究进展进行了归纳总结，为通过植物营养调节技术来提高作物病害防御能力的研究提供理论支撑。【内容】土壤有效硅包括土壤溶液中的单硅酸和易转化为单硅酸的盐类，土壤中有效硅含量一般在50～260 mg/kg。硅虽然不是植物生长发育的必需矿质营养元素，但是硅在减轻植物多种生物和非生物胁迫以及提高植物对病菌的抵抗能力等方面起着重要作用。施硅可以显著地抑制水稻稻瘟病、 纹枯病、 白叶枯病、 胡麻叶斑病，小麦、黄瓜、番茄等植物白粉病等多种病害的发生。关于硅调节植物抗病性的机理，首先提出了机械或物理屏障假设，认为施硅促进了细胞硅化作用的增强，细胞壁角质-硅双层以及表皮细胞乳突的增强，对病菌的入侵起到了物理防御作用。但随着研究的深入，发现物理屏障并非唯一机制，而后提出硅积极参与了生物化学防御过程，发现硅可以诱导感病植物产生酚醛类、黄酮类等抗毒素物质，以及施硅可以提高植物中几丁质酶、过氧化物酶、多酚氧化酶的活性、苯丙氨酸解氨酶等感病植物中病程相关蛋白酶的活性，从而通过化学防御过程提高植物对病害的抵抗能力。随着现代分子技术的发展，从基因组、转录组水平对其防御机制进行了阐明。研究认为硅通过主动的上调感病植物防卫基因及病程相关蛋白基因的表达，以应对病菌侵染。硅诱导植物产生乙烯、茉莉酸、活性氧等系列信号，使植物处于预激活化状态，从而减轻生物胁迫，但是硅在调节植物胁迫信号转导方面的机制还需要深入的研究。【结论】在缺硅土壤中施用硅肥，可以增强作物对病害的抵抗能力，从而大量降低杀菌剂的使用。关于硅调节植物抗病性机理，不能单一归因于某一方面，物理屏障防御机制与生物化学防御过程兼在。硅可能与关键的植物胁迫信号系统相互作用，而最终诱导产生对病原菌的抵抗, 但是这方面的确切机制还不是很清楚，是今后的研究重点。
Abstract:Although silicon (Si) has not been recognized as an essential element for plant growth, its beneficial effects have been demonstrated for a wide variety of plant species under abiotic and biotic stress conditions. Silicon can increase the resistance of plant disease, such as rice blast, rice sheath blight, rice bacterial leaf blight, rice brown spot, powdery mildew, root rot, rust disease and so on. In regard to mechanisms of silicon-mediated plant resistance to pathogen, several different mechanisms have been proposed. The first hypothesis proposed is mechanical or physical barrier, which claims that silicon application leads to more intensive cell silicification, as well as the formation of cuticle-Si double layer and papilla on rice leaf epidermis cells thus impeding pathogen penetration. However, subsequent studies show that the physical barrier mechanism is not the sole mechanism, and an additional biochemical mechanism exists. This novel mechanism supports that silicon application induced more phytoalexins accumulation in plant epidermal cells. Meanwhile, it is found that silicon application enhanced the activities of peroxidase, polyphenoloxidase and chitinase. It is concluded that silicon plays an active and complex role in mediating plant resistance to pathogen. With the development of molecular technique, more studies involve using gene microarray to analyze the interaction of silicon application and pathogen inoculation on the transcriptional profile of plant. It seems to suggest that Si-treated plants react in response to pathogen inoculation through the up-regulation of defense- and pathogenesis-related genes. However, further studies are needed for exploring the detailed mechanisms by which Si mediates plant stress-signaling transduction.
全 文 ：