The Methylation of the PcMYB10 Promoter Is Associated with Green-Skinned Sport in Max Red Bartlett Pear1[C][W]

• Published in: Plant physiology (Bethesda) Vol. 162; no. 2; pp. 885 - 896
• Main Authors: Wang, Zhigang, Meng, Dong, Wang, Aide, Li, Tianlai, Jiang, Shuling, Cong, Peihua, Li, Tianzhong
• Format: Journal Article
• Language: English
• Published: American Society of Plant Biologists 29.04.2013
• Subjects: Genes, Development, and Evolution
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.113.214700

In MRB-G fruits, the expression of PcMYB10 was reduced by the methylation of regions −604 to −911 bp and −1,218 to −1,649 bp in its promoter. As a result, the expression of PcUFGT, a key gene involved in anthocyanin biosynthesis and regulated by PcMYB10, was also reduced. This might cause the inhibition of anthocyanin biosynthesis and the formation of green-skinned sport. Varieties of the European pear ( Pyrus communis ) can produce trees with both red- and green-skinned fruits, such as the Max Red Bartlett ( MRB ) variety, although little is known about the mechanism behind this differential pigmentation. In this study, we investigated the pigmentation of MRB and its green-skinned sport ( MRB-G ). The results suggest that a reduction in anthocyanin concentration causes the MRB-G sport. Transcript levels of PcUFGT (for UDP-glucose:flavonoid 3- O -glucosyltransferase), the key structural gene in anthocyanin biosynthesis, paralleled the change of anthocyanin concentration in both MRB and MRB-G fruit. We cloned the PcMYB10 gene, a transcription factor associated with the promoter of PcUFGT . An investigation of the 2-kb region upstream of the ATG translation start site of PcMYB10 showed the regions −604 to −911 bp and −1,218 to −1,649 bp to be highly methylated. A comparison of the PcMYB10 promoter methylation level between the MRB and MRB-G forms indicated a correlation between hypermethylation and the green-skin phenotype. An Agrobacterium tumefaciens infiltration assay was conducted on young MRB fruits by using a plasmid constructed to silence endogenous PcMYB10 via DNA methylation. The infiltrated fruits showed blocked anthocyanin biosynthesis, higher methylation of the PcMYB10 promoter, and lower expression of PcMYB10 and PcUFGT . We suggest that the methylation level of PcMYB10 is associated with the formation of the green-skinned sport in the MRB pear. The potential mechanism behind the regulation of anthocyanin biosynthesis is discussed.