Transcriptional characterization and response to defense elicitors of mevalonate pathway genes in cotton (Gossypium arboreum L. )

The mevalonate (MVA) pathway is responsible for the biosynthesis of cytosolic terpenes including gossypol and its derivatives, which play an important role in the cotton plant's defense against pathogens and herbivores. In this study, we identified and cloned 17 potentially functional genes encoding enzymes that catalyze the six steps of the MVA pathway in Gossypium arboreum. Expression pattern analysis by qRT-PCR demonstrated that these genes had tissue-specific expression profiles and were most prevalently expressed in roots. Moreover, these genes were up-regulated in response to several elicitors, including methyl jasmonate and salicylic acid, as well as Verticillium dahliae infection and Helicoverpa arm igera infestation. This indicates that the MVA pathway genes are involved in the signaling pathway regulated by exogenous hormones and the resistance of cotton plants to pathogens and herbivores. Our results improve the understanding of cytosolic terpene biosynthesis in Gossypium species and lay the foundation for further research on gossypol biosynthesis.