Independence of color intensity variation in red flesh apples from the number of repeat units in promoter region of the MdMYB10 gene as an allele to MdMYB1 and MdMYBA

MdMYB10 gene expression results in accumulation of anthocyanin in many tissues including flesh of applefruit. The MdMYB1 and MdMYBA genes are close homologues to MdMYB10 gene and both are responsiblefor red color phenotype in apple fruit skin. In the current study, an apple genome sequence draft analysisindicated that these three genes are located in a unique contig. Further analysis suggested that thesehomologues are alleles of a single locus and they differ in a repeated sequence of the promoter region.This repeated sequence ensures high expression level of MdMYB10 in most of the plant tissues whileMdMYB1 and MdMYBA alleles lack such a repeated sequence in their promoters and their expression isconfined to the fruit skin. Also, we suggest a tissue and genome-specific expression pattern for thesethree alleles considering our data and other recent publications. No variation was detected in the sequence or in the number of repeats of MdMYB10 promoter in Iranian red flesh apple geo-variants, pointing that the number of repeat is not related to flesh color intensity or variation, and the repeat elements have occurred once during the evolution.