Integrative analyses of metabolome and transcriptome reveal differences in terpenoids and identify the genes involved in the synthesis of terpenoids in Magnoliae Flos from different varieties

Abstract

Introduction Magnoliae Flos (MF), the dried flower buds of Magnolia denudata Desr., Magnolia biondii Pamp., and Magnolia sprengeri Pamp., is a crucial East Asian medicinal herb used to treat allergic rhinitis and other ailments. However, the molecular basis for its quality differences remains unclear. Methods This study integrates GC-MS-based volatile metabolomics, high-throughput RNA sequencing, and RT-qPCR validation to elucidate the terpenoid metabolic differences and their regulatory mechanisms among the three MF varieties. Results The metabolomic analysis screened 55 differential terpenoids (15 key markers) that distinguish the MF varieties, with terpenoids being the primary metabolic category and the M. sprengeri vs. M. biondii group exhibiting the most differential metabolites. The transcriptomic analysis revealed TPS26 as key candidate genes involved in monoterpene synthesis, while IMPMBI2G0000034954 and IMPMBI2G0000034957 were identified as candidate genes for sesquiterpene synthesis. The expression abundances of these genes exhibited significant linear correlations with the accumulation levels of differential terpenoids, though such coordinated variation does not confirm direct causal regulation. Discussion Collectively, this work reveals the molecular basis of terpenoid diversity in MF, and provides theoretical references for germplasm discrimination, quality evaluation and genetic improvement of medicinal magnolia resources.