GhMYB18 confers Aphis gossypii Glover resistance through regulating the synthesis of salicylic acid and flavonoids in cotton plants

Abstract Accumulating researches confirmed that plant MYB transcription factors are involved in the defense response to herbivores. However, little is known about the target genes and signaling pathways that MYB transcription factors regulate. In this research, we identified the R2R3 MYB transcription factor GhMYB18 from upland cotton (Gossypium hirsutum L.). GhMYB18 is localized throughout the cell and is a functional transcription activation factor. The expression level of GhMYB18 was significantly up-regulated under aphid infestation and exogenous salicylic acid (SA) treatment. Overexpression of GhMYB18 in cotton cotyledons conferred enhanced tolerance of cotton plants to aphid (Aphis gossypii Glover) feeding, expectedly silencing GhMYB18 increased susceptibility of cotton plants to aphid. Subsequent analysis showed that GhMYB18 positively regulates defense-related enzyme activities including catalase (CAT), peroxidase (POD), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL), and increases the synthesis of salicylic acid and flavonoids to participate in the defense response against aphid. These results collectively suggest that the cotton MYB gene GhMYB18 is involved in the plant defense response to aphid attack, which may contribute to cotton aphid control strategies.