Interplay between LvCOP1 and LvMYB1 governs light-induced anthocyanin biosynthesis in lily (Lilium ‘Viviana’)

Abstract

CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1), a ubiquitin E3 ligase, has been identified as a crucial repressor involved in plant development in the absence of light. However, its specific roles in lily (Lilium ‘Viviana’) remain largely unknown. Through transcriptome analysis in lily, a gene (TRINITY_DN102750_c1_g1) that positively influences lily pigmentation was identified. Evolutionary analysis revealed that TRINITY_DN102750_c1_g1 is an ortholog of Arabidopsis COP1, subsequently designated as LvCOP1. The promoter region of LvCOP1 is enriched with multiple cis-acting elements responsive to light, and its expression was regulated by light, indicating that LvCOP1 plays a crucial role in response to light signals. Furthermore, the overexpression of LvCOP1 elevates the anthocyanin content in lily petals. This enhancement is achieved by elevating the expression levels of key genes involved in biosynthesis of anthocyanin, including LvCHS, LvF3H, LvDFR, LvANS, and Lv3GT. Conversely, silencing LvCOP1 had the opposite effect. Additionally, yeast library screening demonstrated an interaction between LvCOP1 and LvMYB1, with the latter being confirmed as a protein that limits the synthesis of anthocyanins. In light of these findings, we propose a model where LvCOP1, in the presence of light, can facilitate the ubiquitination and degradation of LvMYB1, thereby precisely regulating anthocyanin accumulation in lily. This study expands our understanding of COP1 functions, revealing its positive regulatory role in anthocyanin accumulation in lily.