Welan gum promotes camptothecin production in Camptotheca acuminata by activating multiple signaling pathways.

This study aimed to investigate the effect of welan gum on camptothecin (CPT) accumulation in Camptotheca acuminata leaves. We evaluated the impact of welan gum treatment on CPT biosynthesis by measuring CPT accumulation and the expression of key CPT biosynthetic genes in C. acuminata leaves. Transcriptome analysis was performed to elucidate the underlying molecular mechanisms driving welan gum-induced CPT biosynthesis. Welan gum application significantly enhanced CPT accumulation by upregulating the expression of CPT biosynthesis genes. Transcriptome data revealed strong activation of the salicylic acid (SA) signaling pathway through increased SA production, which appears to play a central role in mediating CPT biosynthesis in response to welan gum. In addition to SA signaling, jasmonic acid (JA), abscisic acid (ABA), and gibberellin (GA) signaling pathways also responded to welan gum, highlighting a complex regulatory network underlying the plant's adaptation to microbial polysaccharide signals. Welan gum treatment robustly activates multiple signaling pathways, particularly SA signaling, thereby promoting CPT accumulation in C. acuminata leaves. The coordinated modulation of these pathways reflects the intricate transcriptional reprogramming that balances growth and defense responses, enabling the plant to dynamically adjust to environmental cues triggered by microbial polysaccharides.