Chi-Nan agarwood germplasms constitute a new chemotype of Aquilaria sinensis (Lour.) Spreng

Agarwood has been used for traditional medicines, incenses and perfumes across Asia, the Middle East and Europe. Chi-Nan agarwood (CNA) is the highest-quality of agarwood due to its high resin content and elegant fragrance. In recent years, a series of Chi-Nan germplasms that easily produce agarwood with a high resin content and similar Chi-Nan aroma have been widely cultivated in China. However, the relationship between its species, genetic background, and chemical composition and ordinary agarwood (OA) is unclear; therefore, the applications of these germplasms are limited. In this context, the taxonomic classification and chemical diversity of the agarwood produced by three Chi-Nan germplasms (A11, R21 and B31) were evaluated. The morphological characteristics and DNA barcoding results showed for the first time that the origin species for the three Chi-Nan germplasms was A. sinensis. The three Chi-Nan germplasms had unique morphological characteristics and could be distinguished from each other by SSR. Compared with the characteristics of OA, the alcohol extract content of CNA was significantly higher, and the sesquiterpenoids were more abundant and diverse, but the diversity of 2-(2-phenylethyl) chromones was lower. The sum of the relative contents of 2-(2-phenylethyl) chromone and 2-[2-(4′-methoxyphenyl) ethyl] chromone was 66.22%−79.20% of the total by GC–MS, 7.86–9.41 times higher than that of OA. Based on these results, it is proposed that there are 2 chemotypes, "Chi-Nan type" and "Ordinary type" in A. sinensis, which provided a reference for molecular mechanism studies of agarwood formation of Chi-Nan germplasms and their potential uses as therapeutic products.