Multiomics Insights into Flavonoid-Mediated Light-Induced Yellowing of the Curd in Loose-Curd Cauliflower (Brassica oleracea var. botrytis)

China
cultivates over 400,000 ha of cauliflower (Brassica
oleracea var. botrytis),
with loose-curd types accounting for 90% of production. Due to large
curd size, light exposure during late growth leads to curd yellowing,
reducing commercial value. Manual curd covering is widely used but
is labor-intensive. This study used integrated multiomics to reveal
that light-induced flavonoid accumulation is the primary cause of
curd yellowing. Phenotypic and metabolite analyses showed higher flavonoid
levels in uncovered curds, with baimaside (quercetin-3-O-sophoroside) identified as the key yellowing biomarker by UPLC-MS/MS.
Transcriptomic analysis revealed 2976 differentially expressed genes
enriched in flavonoid biosynthesis and light-responsive pathways.
Dynamic clustering showed early gene repression under covering, correlating
with deyellowing. Promoter and transcription factor analyses demonstrated
that light-responsive regulatory networks mediate this process via
cis-elements. Overall, the findings clarify that light-triggered flavonoid
biosynthesis drives curd yellowing and offer a theoretical and technical
foundation for breeding yellowing-resistant loose-curd cauliflower
varieties.