VERNALIZATION-INSENSITIVE 3-LIKE 2 (VIL2) and PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) act together to suppress anthocyanin accumulation in Arabidopsis
Anthocyanins are a group of secondary metabolites that protect plants from many environmental challenges such as UV light, cold, salt, and pathogens attack. Meanwhile, high temperature was reported to decrease anthocyanin biosynthesis. However, molecular mechanisms on how high temperature negatively modulate anthocyanin accumulation is not fully understood. In this study, we report that VERNALIZATION INSENSITIVE 3-LIKE1 (VIL2) takes part in anthocyanin metabolism by epigenetic suppression of HY5 as well as downstream biosynthetic genes in Arabidopsis plants. Compared to Col-0 and hy5-215 mutant, knock-out mutant of VIL2, vil2-1 exhibited higher accumulation of anthocyanins at high temperature. Transcriptome analysis between Col-0 and vil2-1 also exhibited that anthocyanin biosynthesis was most significantly affected in vil2-1 mutants. Interestingly, PRC2-mediated H3K27me3 was significantly impaired in vil2-1 mutant compared to level of Col-0. It suggested that VIL2 might be involved in the recruitment of PRC2 complex onto a set of target genes related to anthocyanin biosynthesis. As a result, expressions of anthocyanin biosynthetic genes were de-repressed in vil2-1 mutant in comparison to Col-0. Analysis of genome-wide H3K27me3 profile indicated that PAP1/MYB75 and TT8/bHLH42 were greatly enriched with H3K27me3, indicating that these upstream regulators of anthocyanin biosynthesis is tightly controlled by chromatin regulator, PRC2 in Arabidopsis plants. ChIP-qPCR analysis showed that VIL2 directly binds to promoter region of PAP1/MYB75 and TT8/bHLH42. Overall, our study demonstrated that VIL2-mediated enrichment of H3K27me3 contribute to reduction of anthocyanins at high temperature suppress in Arabidopsis. Overall design: The 10 day-old seedlings were harvested for total RNA extraction. Total RNAs were isolated using the RNeasy Plant Mini Kit (QIAGEN, Valencia, CA) in accordance with the manufacturer's instructions. The quantity and quality of RNA were checked with a Nano-400 (Allsheng Instrument Co., China). RNA-seq libraries were prepared using the TruSeq Stranded mRNA LT Sample Prep Kit (Illumina, Inc., USA). Sequencing was performed using an Illumina NovaSeq6000 platform using the paired-end sequencing (Macrogen Co., South Korea).