Genetic diversity in epichloae of Bromus laevipes

Abstract

Fungal endophytes belonging to the genus Epichloë and Neotyphodium can provide substantially greater fitness traits for their host plant. Many of these endophytes are known to produce bioactive compounds (e.g. ergot alkaloids,indolediterpenes, lolines and peramine) that can deter grazing animals. To better understand the selective advantages and how these associations form, we isolated endophytes from Bromus laevipes, a cool-season bunchgrass native to California and Southern Oregon. A total of 58 isolates from 12 different populations were then analyzed for their morphological and genetic characteristics, and each endophyte was defined to the species level. PCR was used to determine the alkaloid genotype of the PER (peramine), EAS (ergot alkaloid), LOL (lolines), and IDT (indole-diterpenes) loci of individuals from each population. The PCR data revealed four distinct genotypes, all of which were positive for two or more different classes of alkaloid. PCR of the mating type genes (MTA and MTB) combined with DNA sequencing of the housekeeping genes, tefA and tubB, provided evidence of the ancestral progenitors and revealed at least three different epichloae species can be hosted by B. laevipes. The diverse evolutionary histories identified within B. laevipes endophytes may provide insight into the broader ecological implications of endophyte-plant symbioses.