Associate Professor Queen's University Kingston, Ontario, Canada
Abstract: The success of invasive plant species is attributed to several factors, including biotic interactions with herbivores, parasitoids, pathogens, pollinators, and below-ground interactions. These interactions are influenced by chemical compounds that plants use for internal signalling, attracting beneficial species, and warning other plants of danger or disturbances. Flavonoids, a group of compounds with antimicrobial and antioxidant properties may play important roles in plant signalling and adaptation to novel environments.
Lythrum salicaria (purple loosestrife), a perennial plant in the Lythraceae family, is widely distributed in Eurasia and has been used for medicinal purposes since ancient times. However, it is considered an invasive weed in North America due to its aggressive spread. Although three specialist herbivores were introduced as biocontrol agents, their effectiveness has been variable. In this study, we investigate the potential mechanisms underlying the invasive success of L. salicaria by reviewing the flavonoid compounds identified in the plant and their roles in flowering control, signalling, and protection against biotic and abiotic stressors.
To further understand the molecular biology of this species, we sequenced, assembled and annotated a draft genome of L. salicaria from a diploid population in the native range. We also sequenced mRNA from the floral tissue of four individuals representing early and late flowering phenotypes from a tetraploid population in the introduced range, which were maintained in a common garden field experiment at Queen’s University Biological Station (QUBS) in Ontario, Canada. Using both genome and transcriptome sequences, we identified candidate genes involved in the flavonoid metabolic pathways and compared them to orthologs from other plant species. We found more than 600 unique transcripts that matched orthologs from the flavonoid pathway with an e-value less than 10e-100. The percent identity ranged from 24% to 94%, indicating both highly divergent and conserved sequences, respectively. We also found differentially expressed genes with structural similarity to flavonoid pathways genes but lacked defined orthologs on GenBank, suggesting potentially novel genes of interest.
Despite the numerous ecological and medicinal studies of L. salicaria, the molecular biology of this species remains poorly understood. By identifying candidate genes involved in the flavonoid pathways, we provide insights into the potential mechanisms underlying the success of this invasive species.