Tissue-specific metabolic profiles and volatile chemodiversity in Camellia ptilophylla: a survey of 16 individuals and eight tissues

Background Camellia ptilophylla is a rare and endemic tea germplasm resource in China, valued for its low or zero caffeine and high theobromine content. However, its morphological traits, biochemical differences among individuals, tissue-specific metabolite distribution patterns, and volatile compounds have not been systematically reported. In this study, we quantified morphological traits and the contents of catechins, theanine, alkaloids, and volatile compounds in individual plants and across different tissues (roots, fruit, semi-lignified stems, lignified stems, one bud with one leaf, second leaf, third leaf, and mature leaf). Results Most individual C. ptilophylla plants contained no caffeine, with an average theobromine content of 34.4 mg/g. Gallocatechin gallate (GCG) was the dominant catechin, accounting for 54% of the total catechin content. Caffeine showed the highest inter-individual variation, while GCG was the most consistent. Catechins and caffeine accumulated mainly in young shoots and declined with leaf age, and theanine was detected only in roots (mean 12.96 mg/g). A total of 89 volatile compounds were detected, with (E)-2-hexenal, linalool, methyl salicylate and benzaldehyde as the dominant contributors, conferring predominantly floral and fruity aroma notes. Conclusions This study provides the systematic profiling of volatile chemodiversity in C. ptilophylla , demonstrating individual-associated aroma variation, and establishes a comprehensive tissue-level metabolic map across eight organs, confirming that theanine was detected exclusively in roots of the three individuals examined. These findings open new possibilities for flavor-oriented breeding and chemotype-guided utilization of this unique plant resource.