Interspecific hybridization and bioactive alkaloid variation increases diversity in endophytic Epichloë species of Bromus laevipes.
Studying geographic variation of microbial mutualists, especially variation in traits related to benefits they provide their host, is critical for understanding how these associations impact key ecological processes. In this study, we investigate the phylogenetic population structure of Epichloë species within Bromus laevipes, a native cool-season bunchgrass found predominantly in California. Phylogenetic classification supported inference of three distinct Epichloë taxa, of which one was nonhybrid and two were interspecific hybrids. Inheritance of mating-type idiomorphs revealed that at least one of the hybrid species arose from independent hybridization events. We further investigated the geographic variation of endophyte-encoded alkaloid genes, which is often associated with key benefits of natural enemy protection for the host. Marker diversity at the ergot alkaloid, loline, indole-diterpene, and peramine loci revealed four alkaloid genotypes across the three identified Epichloë species. Predicted chemotypes were tested using endophyte-infected plant material that represented each endophyte genotype, and 11 of the 13 predicted alkaloids were confirmed. This multifaceted approach combining phylogenetic, genotypic, and chemotypic analyses allowed us to reconstruct the diverse evolutionary histories of Epichloë species present within B. laevipes and highlight the complex and dynamic processes underlying these grass-endophyte symbioses.
['Charlton|Nikki D|ND|', 'Craven|Kelly D|KD|', 'Afkhami|Michelle E|ME|', 'Hall|Bradley A|BA|', 'Ghimire|Sita R|SR|', 'Young|Carolyn A|CA|']
D000470:Alkaloids D031724:Bromus D004224:Diterpenes D060026:Endophytes D055329:Epichloe D004876:Ergot Alkaloids D014644:Genetic Variation D006574:Heterocyclic Compounds, 2-Ring D006824:Hybridization, Genetic D007211:Indoles D010802:Phylogeny D011073:Polyamines D013559:Symbiosis
interspecific hybrid ergot alkaloids lolines indole-diterpenes peramine alkaloid diversity