A CHH Methylation-Ubiquitination Cascade Links Light-Induced Anthocyanin Accumulation in Pear Fruit.

Light exposure in the red-skinned pear cultivar ‘Aohong No. 1’ triggers CHH hypermethylation that silences the RGLG5 promoter, enabling anthocyanin accumulation.

• Why it matters: The DNA methylation targets and downstream mechanisms connecting light to anthocyanin biosynthesis in fruit are not well defined.
• What they did: Using whole-genome bisulfite sequencing and RNA-seq on pear peels before and after light following bag removal, the study found light-induced CHH hypermethylation at RGLG5, including a 420-bp promoter fragment.
• The result: Methylation blocked AP2 binding, downregulated RGLG5, reduced ubiquitin-proteasome degradation of WRKY75L, and allowed WRKY75L to activate MYB10, promoting pigmentation in pear peel and callus.

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