[Cloning and expression of AeMYB4 gene related to stolon development of Amana edulis]

Stolon is an important organ for reproduction and regeneration of Amana edulis. Previous analysis of transcriptome showed that MYB was one of the most active transcription factor families during the development of A. edulis stolon. In order to study the possible role of MYB transcription factors in stolon development, the authors screened out an up-regulated MYB gene named AeMYB4 was by analyzing the expression profile of MYB transcription factors. In the present study, sequence analysis demonstrated that AeMYB4 contained an open reading frame of 756 bp encoding 251 amino acids, and domain analysis revealed that the predicted amino acids sequence contained two highly conserved SANT domains and binding sites for cold stress factor CBF. By multiple sequence alignment and phylogenetic analysis, it is indicated that AeMYB4 clustered with AtMYB15 from Arabidopsis thaliana, belonging to subgroup S2 of R2 R3-MYB. And most of the transcription factors in this subfamily are related to low temperature stress. The GFP-AeMYB4 fusion protein expression vector for subcellular localization was constructed and transferred into Agrobacterium tumefaciens to infect the leaves of Nicotiana benthamiana, and the results showed the protein was located in the nucleus. To investigate the transcriptional activation, the constructed pGBKT7-AeMYB4 fusion expression vector was transferred into Y2 H Gold yeast cells, which proved that AeMYB4 was a transcription activator with strong transcriptional activity. Real-time quantitative PCR was used to detect the expression of AeMYB4 gene in three different development stages of stolon and in leaves, flowers, and bulbs of A. edulis, which indicated that AeMYB4 transcription factor was tissue-specific in expression, mainly in the stolon development stage, and that the expression was the most active in the middle stage of stolon development, suggesting that AeMYB4 gene may play an important role in stolon development. This study contributes to the further research on the function of AeMYB4 transcription factor in stolon development of A. edulis.