Comparative analysis of genetic structures and aggressiveness of Fusarium pseudograminearum populations from two surveys undertaken in 2008 and 2015 at two sites in the wheat belt of Western Australia

Abstract

Fusarium crown rot (FCR), caused predominantly by Fusarium pseudograminearum (Fp) in Australia, is an important fungal disease of wheat and barley. FCR causes significant yield losses and reduced grain quality worldwide. This study investigated the population dynamics of FCR‐causing F. pseudograminearum isolates from Western Australia (WA), a major wheat‐growing region. Wheat samples were collected from a total of seven different sites in 2008 and 2015. Two sites, Tammin and Karlgarin, with moderate to high FCR incidence, were intensively sampled in both years. The results revealed significant increase in Fp isolation frequency between 2008 and 2015. Over 86% of 1100 Fusarium isolates were Fp in 2015 compared with 59% of 639 isolates from 2008. Mating type idiomorphs, toxin chemotypes and population genetic structures were determined for a subset of 279 Fp isolates (132 isolates from 2008 and 165 from 2015). Mating type analysis revealed differences in MAT1‐1 and MAT1‐2 distributions between Tammin and Karlgarin for both years. Results also showed that 97.6% of Fp isolates analysed had the 3‐ADON trichothecene chemotype. Additionally, for the first time in Australia, the 15‐ADON chemotype was identified in 2.3% and 2.4% of Fp isolates from 2008 and 2015, respectively. The genetic structure of Fp population determined using 21 cleaved amplified polymorphic sequence (CAPS) markers revealed a high level of genetic variation within and between populations. In addition, 2015 isolates from Tammin and Karlgarin were significantly more aggressive (P < 0.0001) than 2008 isolates. This finding may have implications in managing this significant fungal disease.

Population Genetic Analyses and Trichothecene Genotype Profiling of Fusarium pseudograminearum Causing Wheat Crown Rot in Henan, China

“…In this study, for the first time, we determined the mating types of F. pseudograminearum strains in Henan. Our results revealed that F. pseudograminearum strains have both mating idiomorphs, which is consistent with previous studies indicating that the pathogen segregates for both MAT-1 and MAT-2 [4,6,7,40,41]. Although significant ratio differences were detected for the two mating types, MAT-1 and MAT-2, between individual sampling sites, a well-balanced 1:1 ratio of the F. pseudograminearum population in Henan was found overall.…”

“…Of the 44 samples collected from different field sites in Queensland and New South Wales in 2010, DON concentrations in straw from 26 sites exceeded 1 mg/kg, with a percentage of 59% [17]. Similarly to the situation in the Fusarium graminearum species complex (FGSC), the main pathogen of wheat FHB worldwide, three different trichothecene genotypes were identified in F. pseudograminearum species [6,20,26,27], namely, 3-acetyl DON, 15-acetyl DON, and nivalenol (NIV) types. The different toxicological effects observed among the three trichothecene-producing strains make their identification in a given area important in terms of food/feed safety and disease management.…”

“…Fungal culture isolation was performed as previously described by Khudhair et al [6], with minor changes. In brief, the symptomatic crown/sub-crown tissues were cut into small segments (about 2 cm in length).…”

“…According to the surveys conducted to date, FCR is caused by several species of the genus Fusarium, with F. pseudograminearum being particularly prevalent. The disease has been documented in many other countries throughout the world since its discovery in Queensland, Australia, in 1951, including Africa, America, Europe, and Asia, with the most severe cases occurring in Australia [4][5][6][7][8][9][10]. In Australia, the primary pathogens associated with this disease include F. pseudograminearum, F. culmorum, and Fusarium acuminatum [11].…”

Comparison of disease severity caused by four soil-borne pathogens in winter cereal seedlings

“…Three triticale genotypes (Ningadhu, Hawkeye and Berkshire) have been reported as susceptible to F. pseudograminearum (Klein et al 1989;Knight and Sutherland 2017), and low or zero levels of disease have been measured in oat cultivars following inoculation with F. pseudograminearum (Nelson and Burgess 1994;Burgess et al 2001;Percy et al 2012). Further to varietal rankings, research into F. pseudograminearum has included the infection process of the fungus (Burgess et al 1975;Wildermuth and McNamara 1994;Percy et al 2012;Knight and Sutherland 2016), genetic resistance including testing genetic structures, aggressiveness and toxigenicity of F. pseudograminearum populations (Bentley et al 2008;Obanor and Chakraborty 2014;Khudhair et al 2019), and yield loss in barley and bread wheat cultivars (Klein et al 1989;Liu et al 2012;Kirkegaard et al 2004).…”