Results
Phenotypic variations of AR secretory cavities amongA. lancea natural accessions
In order to make a rational comparison of metabolites in different AR, we selected three representative accessions grown in different geographic regions of China (Figure 1A). The samples were collected in wild (Figure 1B) and the roots were used for analysis (Figure 1C). The secretory cavity of AR from an accession collected in Hubei province (hereafter referred to as HAR) is in yellow (Figure 1D), whereas AR from an accession grown in Shaanxi province (namely SAR) has cinnabar-like red secretory cavities (Figure 1E). The colour of secretory cavity in AR of an accession harvested in Jiangsu province (namely JAR) is more diverse, with some (e.g. in cortex) are red and others are yellow (e.g.in phloem, xylem and pith) (Figure 1F).
Previous studies have shown that AR contains mainly volatile oils including sesquiterpenes, terpenoids, polyacetylenes and monoterpenes and steroids (Xu et al., 2022). To reveal major chemical profiles, we collected wild ARs from the three A. lancea accessions at the same season and performed untargeted GC-MS (n=6 for each accession) analysis (see Method). As expected, this analysis revealed distinct metabolite profiles among the three natural accessions (Figure S2). In total, we identified 56 compounds, including 42 sesquiterpenes and 10 polyacetylenes. Of those, 54, 47 and 27 were identified in JAR, SAR and HAR, respectively. This analysis suggested that sesquiterpenes and polyacetylenes are major metabolites in the three selected ARs. In addition, there are likely significant chemical variations among the three A. lanceaaccessions.