Alkaloid Genotype Diversity of Tall Fescue Endophytes

Abstract

ABSTRACTTall fescue {Festuca arundinacea Schreb. [syn Lolium arundinaceum (Schreb.) Darbysh.]}, a common forage grass used in temperate regions, forms mutually beneficial symbioses with hybrid epichloid endophytes, including the well‐described species Neotyphodium coenophialum. These endophytes confer many benefits to their plant hosts, including the production of bioactive alkaloids that deter insect and/or mammalian herbivory. Individual seeds from 176 tall fescue accessions were collected worldwide, including representatives of both Continental and Mediterranean morphotypes, and screened via polymerase chain reaction (PCR) for endophyte incidence and potential chemotypic diversity. A total of 89 endophyte‐infected seed lines were identified and screened with markers representing key genes within the four alkaloid biosynthesis loci, EAS (ergot alkaloids), IDT (indole‐diterpenes), LOL (lolines), and PER (peramine). Endophyte alkaloid genotypes based on alkaloid biosynthetic gene‐specific patterns were developed for each infected seed, and the alkaloid potential for each endophyte was predicted. Genotype profiles were compared to those of 11 known tall fescue endophytes to identify genotype variation within species as well as the prevalence of each species. Some Plant Introduction (PI) accessions arising from multiple germplasm sources were determined to contain two to three independent endophyte genotypes across the seeds tested. The results from this study provide insight into the genotype and chemotype diversity of endophytes present in populations of tall fescue worldwide and support evidence that tall fescue endophytes are host specific.