The lre‐miR159a‐LrGAMYB pathway mediates resistance to grey mould infection in Lilium regale

Grey mould is one of the most determinative factors of lily growth and plays a major role in limiting lily productivity. MicroRNA159 (miR159) is a highly conserved microRNA in plants, and participates in the regulation of plant development and stress responses. Our previous studies revealed that lre‐miR159a participates in the response of Lilium regale to Botrytis elliptica according to deep sequencing analyses; however, the response mechanism remains unknown. Here, lre‐miR159a and its target LrGAMYB gene were isolated from L. regale. Transgenic Arabidopsis overexpressing lre‐MIR159a exhibited larger leaves and smaller necrotic spots on inoculation with Botrytis than those of wild‐type and overexpressing LrGAMYB plants. The lre‐MIR159a overexpression also led to repressed expression of two targets of miR159, AtMYB33 and AtMYB65, and enhanced accumulation of hormone‐related genes, including AtPR1, AtPR2, AtNPR1, AtPDF1.2, and AtLOX for both the jasmonic acid and salicylic acid pathways. Moreover, lower levels of H(2)O(2) and [Formula: see text] were observed in lre‐MIR159a transgenic Arabidopsis, which reduced the damage from reactive oxygen species accumulation. Taken together, these results indicate that lre‐miR159a positively regulates resistance to grey mould by repressing the expression of its target LrGAMYB gene and activating a defence response.