陆地棉PPO基因全基因组鉴定及对黄萎病菌的响应分析

Genome-Wide Identification of PPO Gene Family Members and Their Response to Verticillium dahliae in Upland Cotton

【目的】多酚氧化酶(Polyphenol oxidases,PPO)广泛参与植物抵抗病虫害等生物逆境胁迫的过程。本研究旨在研究棉花中的PPO基因及其表达模式,验证多酚氧化酶与棉花抗黄萎病的关系。【方法】分析了黄萎病菌V991侵染下异源四倍体陆地棉TM-1根系中PPO酶活力变化,并利用TM-1的基因组数据库,鉴定相关基因,并进行生物信息学和表达分析。【结果】共筛选到13个候选GhPPO基因。这些基因都不含内含子,所编码的蛋白包含2个铜离子结合位点和PPO的保守序列(酪氨酸酶、DWL和KFDV保守结构域)。进化分析显示,陆地棉PPO基因的种内相似性大于种间相似性,并且相互之间形成了多对重复基因。GhPPO的表达量差异较大,少数基因具有组织特异表达的特性,多数基因在棉花不同组织中表达量都很低。实时荧光定量聚合酶链式反应分析结果表明:GhPPO6D在棉花根系中表达量较高,且在黄萎病菌V991侵染后上调。【结论】GhPPO6D可能参与了棉花与黄萎病菌的互作过程,与V991侵染后棉花根系PPO酶活力上升相关。

b[Objective] Polyphenol oxidases（PPOs） are ubiquitous among plants and have been shown to be involved in defense responses to biotic stresses, such as pathogens and insects. The aim of this study was to verify PPO genes and their expression patterns in upland cotton and determine the relationship between PPO and cotton resistance to Verticillium dahliae. [Method] We analyzed changes in PPO activity in allotetraploid cotton TM-1 roots after V991（V. dahliae） inoculation, and isolated related genes from the TM-1 genome database. Bioinformatics and expression analysis were used to characterize the isolated genes.[Result] 13 putative PPO genes were isolated, all of which were intron-free and encoded proteins containing two copper ion binding sites and conserved PPO domains（tyrosinase, DWL and KFDV domain）. Phylogenetic analysis revealed that there was greater genetic diversity in PPO genes within species than between species. GhPPO genes were duplicated, most of which were lowly expressed in all tissues examined, only a few showed tissue-specific expression in different organs. Quantitative real-time polymerase chain reaction showed that GhPPO6 D was highly expressed in cotton roots and induced by V. dahliae inoculation.[Conclusion] These results indicated that GhPPO6 D may participate in the interaction between cotton and V. dahliae and could be responsible for the up-regulation of PPO activity after V991 infection.