Abstract：MdMYB1 is an important transcription factor to promote the accumulation of anthocyanin on apples. The yellowgreen apple turns red after bag removal. In order to study the regulatory mechanisms of anthocyanin biosythetic genes expression, we analyzed the effects on the expression level of the MdMYB1 gene in peels of yellowgreen apple Golden Delicious and Mutsu, red apple Fuji and deep red apple Starking by light; The studys showed that the colouring rate and area on different varieties were related with the transcript expression rate and cumulation of the transcription factor MdMYB1. We studied the changes on the relative expression levels of the structural gene phenylalanine ammonia-lyase (MdPAL), anthocyanin synthase (MdANS), Chalcone isomerase (MdCHI) and flavonoid-3-O-glycosyltransferase (MdUFGT) during the period of the pigmentation by paper-covering treatment on Golden Delicious and Starking fruits. The analysis results showed that the transcription factor MdMYB1 and structural gene MdPAL,MdANS, MdCHI and MdUFGT expressed continuously in the process of colouring, but the Golden Delicious not. The expression patterns of the gene MdMYB1 was the same as the structural gene MdCHI, and was similar to the MdPAL. By analyzing the transcription factor MdMYB1 and structural genes MdPAL and MdCHI promotor sequence of the apple Golden Delicious, its transcription factor was MdMYB1-2 that promoter region had many G-box binding sites of lights. We inferred the phytochrome regulated the transcription factor MdMYB1-2 by its G-box binding sites. The gene MdCHI promoter region contained the Cis-acting elements MBS, and the MdPAL promoter region contained the Cis-acting elements MBS and MBSⅡ. These results showed the transcription factor MdMYB1 regulated the expression of the structural gene MdCHI , and it likely regulated MdPAL or was closely related. These results showed the Starking color completely in that it was likely related with continuous and coordinate expression of the transcription factor MdMYB1 and structural gene during the period of coloring, while the structural genes that was regulated by light-induced transcription factor MdMYB1 played a decisive role during the Golden Delicious apples coloring.
