Use of DNA barcoding and eDNA metabarcoding to elucidate the taxonomy and distribution of Pyrenophora spp. infecting forage grasses

Abstract

Fungal pathogens of the genus Pyrenophora are economically important diseases of forage grasses, namely perennial ryegrass (Lolium perenne), yet are largely understudied in comparison to Pyrenophora spp. infecting food crops. Fundamental taxonomic issues have yet to be resolved, and there has been little application of novel PCR-based molecular analyses such as DNA barcoding and DNA metabarcoding in their study. This project reviews literature on the morphology and traditional culturing techniques of Pyrenophora spp. infecting forage grasses, providing a summary of these historic works and a refined protocol with which to culture species. Since many taxonomic decisions in the
genus still rely on this morphological work, this study will demonstrate how DNA barcoding can be applied to solve identification issues and stabilise taxonomy where comparative morphology alone was inadequate. Novel PCR-based tools for the detection of these species are then demonstrated, such as species and genus specific PCR primer pairs. The use of DNA metabarcoding is then exemplified in screening leaf and seed tissues for fungal diseases including Pyrenophora, allowing analyses of pathogens within the wider fungal community. These findings have implications for both agricultural and ecological fields, particularly for plant breeders looking to breed Pyrenophora resistant varieties of L. perenne. Given the rapid evolution of DNA-based analyses in modern fungal taxonomy, this work demonstrates how understudied taxa can be reviewed with these novel technologies.

Date of Award	2023
Original language	English
Awarding Institution	Aberystwyth University
Supervisor	Gareth Griffith (Supervisor)