Abstract:In order to study the function of MAX1 in the regulation of apple branching, we cloned the MdMAX1 gene by PCR from the axillary buds of Malus domestica ‘Nagafu 2’, and carried out the bioinformatics and expression level analysis. We further analyzed the promoter activity of MdMAX1 by GUS staining. The results showed that: (1) apple MAX1 was successfully cloned and its ORF was 1 620 bp, encoding 539 amino acids. Phylogenetic analysis and motif analysis showed that MdMAX1 was similar to known A1 type MAX1. (2) qRTPCR analysis showed that MAX1 was highly expressed in the stems of ‘Changfu 2’ grafted seedlings, and also in axillary buds. RNAseq analysis showed that the expression level of MAX1 in apple axillary buds decreased significantly after treated with 6BA for 96 h. (3) The promoter sequence of ‘Changfu 2’ MdMAX1 (1 500 bp) was successfully cloned. The cis acting element prediction showed that there was a light response element in the promoter sequence of MdMAX1. GUS activity analysis showed that the activity of MAX1 promoter was weakened by light treatment. This study provides a basis for further research on the function of MAX1 involved in the synthesis of SLs in regulating apple branches in the future.