Virus-induced gene silencing (VIGS) is a reverse genetic tool used to identify the function of individual genes by reducing their expression. Here VIGS was applied to identify the role of four genes in G. hirsutum; Polyphenol Oxidase (GhPPO), Phosphatidylserine Synthase (GhPSS), Anthocyanidin synthase (GhANS), and Anthocyanidin Reductase (GhANR) in verticillium wilt disease occurring in cotton. Silencing of GhPPO and GhPSS showed abnormal leaf growth such as leaf thinning, reduced leaf size, and leaf curling phenotype which indicates their importance in normal leaf development. RT-PCR and qPCR results showed reduced transcript levels of GhPPO, GhPSS, GhANS, and GhANR in TRV inoculated plants. Moreover silencing of four genes in cotton cultivar FM9160, partially resistant to Verticillium wilt disease compromised resistance by infecting with “King isolate” which is a more aggressive defoliating strain of Verticillium dahliae. The reduced mRNA level of GhPPO and GhPSS makes the cotton plants more susceptible approximately 80% and 76% of leaf wilting were observed while in GhANS and GhANR 66% and 62% leaf wilting were shown. In conclusion, this is the first report showing that the cotton gene GhPPO, GhPSS involved in resistance to Verticillium dahliae and have an important role in normal leaf development in G. hirsutum.

病毒诱导的基因沉默 (VIGS) 是一种反向遗传工具，用于通过减少单个基因的表达来识别它们的功能。这里应用 VIGS 鉴定了四个基因在G. hirsutum 中的作用；棉花黄萎病中的多酚氧化酶( GhPPO )、磷脂酰丝氨酸合酶( GhPSS )、花色素合酶( GhANS ) 和花色素还原酶( GhANR )。GhPPO和GhPSS 的沉默表现出异常的叶片生长，例如叶片变薄、叶片尺寸减小和叶片卷曲表型，这表明它们在正常叶片发育中的重要性。RT-PCR 和 qPCR 结果显示，TRV 接种植物中GhPPO、GhPSS、GhANS和GhANR 的转录水平降低。此外，棉花栽培品种 FM9160 中的四个基因的沉默，部分抗黄萎病，通过感染“国王分离株”，这是一种更具攻击性的大丽轮枝菌脱叶菌株，从而削弱了抗性。GhPPO和GhPSS 的mRNA 水平降低使棉花植株更易感，大约 80% 和 76% 的叶枯萎被观察到，而显示了 GhANS和GhANR 66% 和 62% 的叶子萎蔫。综上所述，这是首次报道棉花基因GhPPO、GhPSS参与大丽轮枝菌抗性并在陆地棉正常叶片发育中发挥重要作用。