Potassium-induced plant resistance against soybean cyst nematode via root exudation of phenolic acids and plant pathogen-related genes

Soybean cyst nematode (SCN) is a severe soil borne disease. The control of this disease is still a worldwide problem in agriculture. In this study, we found that application of potassium (K) fertilizer could decrease the occurrence of SCN at two field sites. Furthermore, the application of K could suppress Heterodera glycines with the activation of Phenylalanine Ammonia Lyase (PAL) and Polyphenol Oxidase (PPO) expression via pot experiments in a greenhouse. The release of cinnamic, ferulic and salicylic acids was significantly enhanced by K application of 3 mM, and each of three acids can dramatically constrain Heterodera glycines in vitro. This research indicated that K induce multiple mechanisms to improve the resistance of soybean against SCN and provide a new strategy to control SCN in fields with nutrient application.大豆胞囊线虫（Soybean cyst nematode, SCN）是一种危害性极强的土传病害，其防控至今仍是全球农业生产面临的共性难题。本研究发现，在两个田间试验点施用钾肥（钾，K）均可降低大豆胞囊线虫的发病概率。此外，通过温室盆栽试验证实，钾肥施用可通过激活苯丙氨酸解氨酶（Phenylalanine Ammonia Lyase, PAL）与多酚氧化酶（Polyphenol Oxidase, PPO）的基因表达，抑制大豆孢囊线虫（Heterodera glycines）的增殖。当钾肥施用量为3 mM时，大豆根系分泌的肉桂酸、阿魏酸与水杨酸含量显著提升，且这三种物质在离体条件下均可显著抑制大豆孢囊线虫的活性。本研究表明，钾肥可通过多重调控机制提升大豆对大豆胞囊线虫的抗病性，为田间通过养分施用防控该病害提供了全新策略。