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McMYB10 regulates coloration via activating McF3′H and later structural genes in ever‐red leaf crabapple

Tian, Ji, Peng, Zhen, Zhang, Jie, Song, Tingting, Wan, Huihua, Zhang, Meiling, Yao, Yuncong
Plant biotechnology journal 2015 v.13 no.7 pp. 948-961
Arabidopsis, Malus, Nicotiana tabacum, anthocyanins, apples, biosynthesis, callus, color, cultivars, cyanidin, fruit trees, gel electrophoresis, heterologous gene expression, high performance liquid chromatography, leaf development, leaves, mutants, promoter regions, structural genes, temperature, tobacco, tree breeding, yeasts
The ever‐red leaf trait, which is important for breeding ornamental and higher anthocyanin plants, rarely appears in Malus families, but little is known about the regulation of anthocyanin biosynthesis involved in the red leaves. In our study, HPLC analysis showed that the anthocyanin concentration in ever‐red leaves, especially cyanidin, was significantly higher than that in evergreen leaves. The transcript level of McMYB10 was significantly correlated with anthocyanin synthesis between the ‘Royalty’ and evergreen leaf ‘Flame’ cultivars during leaf development. We also found the ever‐red leaf colour cultivar ‘Royalty’ contained the known R₆: McMYB10 sequence, but was not in the evergreen leaf colour cultivar ‘Flame’, which have been reported in apple fruit. The distinction in promoter region maybe is the main reason why higher expression level of McMYB10 in red foliage crabapple cultivar. Furthermore, McMYB10 promoted anthocyanin biosynthesis in crabapple leaves and callus at low temperatures and during long‐day treatments. Both heterologous expression in tobacco (Nicotiana tabacum) and Arabidopsis pap1 mutant, and homologous expression in crabapple and apple suggested that McMYB10 could promote anthocyanins synthesis and enhanced anthocyanin accumulation in plants. Interestingly, electrophoretic mobility shift assays, coupled with yeast one‐hybrid analysis, revealed that McMYB10 positively regulates McF3′H via directly binding to AACCTAAC and TATCCAACC motifs in the promoter. To sum up, our results demonstrated that McMYB10 plays an important role in ever‐red leaf coloration, by positively regulating McF3′H in crabapple. Therefore, our work provides new perspectives for ornamental fruit tree breeding.