Endangered species and their secondary metabolites

3rd paper out in 2023

Our EPP labs have remained engaged in research of invasive plants [link Helianthus - personnel Jacob]. One such plant is Pityopsis ruthii, an endangered flowering aster that only grows along limited sections of two rivers (Ocoee and Hiwassee) in Tennessee, within cracks of massive phyllite boulders situated between the river channel and adjacent forested slopes. Our long-term goal is to understand the mechanisms behind P. ruthii’s adaptation to restricted areas in Tennessee, with intermittent floods and prolonged drought.

In this study, we profiled the volatile terpenes, specifically in flowers, aiming to uncover the genomic and molecular basis of their biosynthesis in P. ruthii using transcriptomic and biochemical approaches. From various tissues, P. ruthii flowers were the richest in terpenes, and produced 4 monoterpenes and 10 sesquiterpenes as part of the noticable bouquet. Floral terpenes may play important roles for the biology and adaptation of P. ruthii to its limited range.

Using transcriptome dat from the flowers, 67 putative terpene synthase (TPS) contigs were detected. Seven full-length TPS genes encoding putative monoterpene and sesquiterpene synthases were cloned and functionally characterized, and 5 of them showed in vitro activity. Two TPSs showed striking similarity in amino acid sequence with some changes clearly affecting their specific activity / products. One other proved a very promiscuous enzyme, which collectively bodes well for artificial production of terpenes.

We are grateful to UTK Plant Sciences scholars and Max Planck collaborators for all the cool stuff they contributed towards this report!