Population structure of South African and Australian Pyrenophora teres isolates

Abstract

There are two recognized forms of the disease net blotch of barley: the net form caused by Pyrenophora teres f. teres (PTT) and the spot form caused by P. teres f. maculata (PTM). In this study, amplified fragment length polymorphism analysis was used to investigate the genetic diversity and population structure of 60 PTT and 64 PTM isolates collected across Australia (66 isolates) and in the south-western Cape of South Africa (58 isolates). For comparison, P. tritici-repentis, Exserohilum rostratum and Bipolaris sorokiniana samples were also included in the analyses. Both distance-and model-based cluster analyses separated the PTT and PTM isolates into two strongly divergent genetic groups. Significant variation was observed both among the South African and Australian populations of PTT and PTM and among sampling locations for the PTT samples. Results suggest that sexual reproduction between the two forms is unlikely and that reproduction within the PTT and PTM groups occurs mainly asexually.

Genetic variation of Pyrenophora teres f. teres isolates in Western Australia and emergence of a Cyp51A fungicide resistance mutation

“…However, data for PTT genetic variation in WA has so far been limited to a wide‐scale study involving nine WA isolates collected over a 32‐year period by Lehmensiek et al . () and 19 isolates by Serenius et al . ().…”

“…PTT is therefore an obligate outcrossing fungus, resulting in genetically diverse populations (Rau et al ., , ; Liu et al ., ; Akhavan et al ., ,b). Genetic differences between populations have been observed regionally within Sardinia, the Czech Republic and over intercontinental distances (Rau et al ., ; Serenius et al ., ; Lehmensiek et al ., ; Leišová‐Svobodová et al ., ).…”

“…Several studies have examined pathotype variation in Western Australia (WA; Khan & Boyd, 1969;Khan, 1982;Gupta & Loughman, 2001;Fowler et al, 2017), a region where barley cultivation is relatively recent and geographically isolated. However, data for PTT genetic variation in WA has so far been limited to a wide-scale study involving nine WA isolates collected over a 32-year period by Lehmensiek et al (2010) and 19 isolates by Serenius et al (2007). As knowledge of the standing genetic variation is essential when considering effective resistance strategies against a disease, a clearer understanding of the composition of WA PTT isolates formed the basis for this study.…”

Genetic structure of a Pyrenophora teres f. teres population over time in an Australian barley field as revealed by Diversity Arrays Technology markers

“…Molecular markers such as random amplified polymorphic DNA (RAPD), amplified fragment length polymorphisms (AFLP) and simple sequence repeats (SSR) have been used to study genetic variability of Ptt populations (Peever & Milgroom, 1994;Peltonen et al, 1996;Jonsson et al, 2000;Rau et al, 2003;Wu et al, 2003;Leisova et al, 2005;Serenius et al, 2007;Bogacki et al, 2010;Lehmensiek et al, 2010;McLean et al, 2010). These studies relied on technologies that used gel electrophoresis, were low throughput, had ascertainment bias in the case of SSR markers and lacked reproducibility between laboratories in the case of RAPD markers (Jaccoud et al, 2001).…”

Secretome analysis of virulentPyrenophora teresf. teresisolates

“…Although Australian Ptt isolates are relatively similar, genetic variation appears to be correlated with sampling location, time of sampling, and the barley cultivar from which they were sampled . Furthermore, the virulence of Ptt isolates has been rapidly evolving in Australia with the identification of isolates that have overcome resistance on the barley cultivars Keel, Maritime, and Fleet since 2009 (H. Wallwork, personal communication ; https://www.grdc.com.au/Research-and-Development/GRDC-Update-Papers/2014/02/Cereal-disease-update-and-use-of-fungicides-on-fertiliser-and-seed).…”