Chromosome-Level Genome Assembly of Tea Cultivar “Aijiaowulong” Elucidates the Molecular Mechanism of Osmanthus-like Aroma Formation

Beiyuan Tribute Tea is produced mainly from the cultivar “Aijiaowulong” (AJWL), noted for its distinctive osmanthus-like aroma, yet its molecular basis remains unclear. We generated a chromosome-level AJWL genome (3.16 Gb; contig N50 130.03 Mb). Structural-variation analyses indicated AJWL is closer to Rougui (RG) and Tieguanyin (TGY) than to Shuchazao (SCZ), which shows clearer structural divergence. We integrated multiomics across the full processing workflow, along with sensory evaluation, aroma recombination and omission assays, and benchmarked against two osmanthus cultivars, identifying ( Z )-β-ocimene, linalool, α-ionone, and dihydro-β-ionone as principal aroma contributors. Withering and shaking were dominated by enzymatic reactions, driving accumulation of ( Z )-β-ocimene and linalool, whereas fixation and drying promoted heat-driven carotenoid cleavage, increasing α-ionone and dihydro-β-ionone. We further identified 29 structural genes in the MEP pathway, the MVA pathway and carotenoid-related pathways, mainly terpene synthase (TPS) and carotenoid cleavage dioxygenase (CCD), whose mechanically induced expression tightly tracked key volatile dynamics.