链格孢菌Alternaria alternata引起的棉花轮纹斑病,是导致棉花早衰发生的主要成因之一,严重危害棉花生产。香豆素合成途径作为合成植保素的一条代谢支路,其产物能够抑制病原菌,增强植物的抗病性。为了揭示该途径在棉花抗链格孢菌中的作用,本文利用棉花皱缩病毒介导的基因沉默技术,通过对棉花香豆素合成途径中编码关键酶基因的沉默抑制,来解析其在棉花抗链格孢菌中的作用,所选择的基因有编码苯丙氨酸解氨酶(PAL)的基因Ghpal、肉桂-4-羟化酶(C4H)基因Ghc4h和4香豆酸-辅酶-A(4CL)的基因Gh4cl。结果显示,Ghpal、Ghc4h和Gh4cl基因受链格孢菌诱导转录,表明这些基因可能参与了棉花对链格孢菌的抗性反应。Ghpal、Ghc4h和Gh4cl基因分别被沉默后,结果显示各基因沉默植株对链格孢菌的抗性下降,表现为接种链格孢菌后,基因沉默植株的病情指数分别为43.36、38.27和44.78,显著高于野生型和VIGS空载体对照植株。这表明,Ghpal、Ghc4h和Gh4cl参与了棉花对链格孢菌的抗性反应。此外,离体条件下给Ghpal、Ghc4h和Gh4cl基因沉默植株叶片饲喂外源香豆素,结果发现基因沉默植株对链格孢菌的抗性得到恢复。这一结果进一步表明香豆素合成途径在棉花抗链格孢菌中起着重要作用。 Alternaria alternata caused by cotton leaf spot disease is one of the major causes of premature aging in cotton, seriously endangering the cotton production. Coumarin synthesis pathway As a metabolic branch of phytoalexin, its products can inhibit pathogens and enhance plant disease resistance. In order to reveal the function of this pathway in Alternaria solani, we used the cotton shrinkage virus-mediated gene silencing technology to analyze the silencing of the key enzyme gene in cotton coumarin synthesis pathway, The selected genes were Ghpal, which codes for phenylalanine ammonia lyase (PAL), Ghc4h, a cinnamic-4-hydroxylase (C4H) gene, and 4 coumaric acid-coenzyme-A (4CL) gene Gh4cl. The results showed that Ghpal, Ghc4h and Gh4cl genes were induced by Alternaria alternata, indicating that these genes may be involved in the resistance of cotton to Alternaria. Ghpal, Ghc4h and Gh4cl genes were silenced, the results showed that the resistance of each gene silencing Alternaria alternata decreased, the performance of inoculation Alternaria, gene silence plants disease index were 43.36,38.27 and 44.78, respectively, Significantly higher than wild-type and VIGS empty vector control plants. This indicates that Ghpal, Ghc4h and Gh4cl are involved in cotton's resistance to Alternaria. In addition, Ghpal, Ghc4h and Gh4cl gene silencing plant leaves were fed exogenous coumarin in vitro and the results showed that the resistance of gene silencing plants to Alternaria was restored. This result further indicates that the coumarin synthesis pathway plays an important role in Alternaria alternata.