An R2R3 MYB Transcription Factor Ghmyb18 Confers Cotton Aphid Resistance Through Regulating The Synthesis of Flavonoids in Cotton Plants

Abstract Accumulating researches confirmed that plant MYB transcription factors are involved in the defense response to insect herbivores. However, the target genes and signaling pathways they regulate are still unknown. Here, we identified the R2R3 MYB transcription factor GhMYB18 from upland cotton (Gossypium hirsutum L.). GhMYB18 was a functional transcription activation factor. The expression level of GhMYB18 was significantly up-regulated under the conditions of aphid infestation and exogenous SA treatment. Overexpression of GhMYB18 in cotton cotyledons conferred enhanced tolerance to the aphid (Aphis gossypii Glover), while the silence of GhMYB18 expression led to increased susceptibility of cotton plants to aphid. Subsequent analysis showed that GhMYB18 activated defense-related enzymes including CAT, POD, PPO and PAL, induced the synthesis of salicylic acid and flavonoids to participate in the defense response against aphid. These results collectively prove that the cotton MYB gene GhMYB18 modulated the plant defense response to aphid attack, which may offer guide strategies for the prevention of cotton aphid.