Boreal peatlands play a crucial role in global carbon cycling, acting as an important carbon reservoir. However, little information is available on how peatland microbial communities are influenced by natural variability or human-induced disturbances. In this study, we have investigated the fungal diversity and community structure of both the organic soil layer and buried wood in boreal forest soils using high-throughput sequencing of the internal transcribed spacer (ITS) region. We have also compared the fungal communities during the primary colonization of wood with those of the surrounding soils. A permutational multivariate analysis of variance (PERMANOVA) confirmed that the community composition significantly differed between soil types ( P < 0.001) and tree species ( P < 0.001). The distance-based linear models analysis showed that environmental variables were significantly correlated with community structure ( P < 0.04). The availability of soil nutrients (Ca [ P = 0.002], Fe [ P = 0.003], and P [ P = 0.003]) within the site was an important factor in the fungal community composition. The species richness in wood was significantly lower than in the corresponding soil ( P < 0.004). The results of the molecular identification were supplemented by fruiting body surveys. Seven of the genera of Agaricomycotina identified in our surveys were among the top 20 genera observed in pyrosequencing data. Our study is the first, to our knowledge, fungal high-throughput next-generation sequencing study performed on peatlands; it further provides a baseline for the investigation of the dynamics of the fungal community in the boreal peatlands.

Fusarium head blight (FHB) is a major fungal disease that contributes to severe economic losses for wheat and barley production in Canada and other parts of the world. Rapid developments in molecular biology over the past three decades have improved the ability to devise predictive management tools to combat the effects of the disease. Important aspects of Fusarium species in terms of the epidemiology associated with FHB in wheat and barley have been reported. The role of mycotoxin production in the epidemiology of the disease is beginning to receive much needed research attention. Evolutionary factors and the use of fungicides have resulted in more virulent forms of the FHB pathogens. Advances in next-generation sequencing technologies, including whole genome sequencing (WGS), genome-wide association studies (GWAS), genotyping by sequencing (GBS) and RNA sequencing (RNA-Seq) have facilitated the selection of resistant breeding lines through marker-assisted selection. Many quantitative trait loci (QTL) associated with moderate disease resistance have been identified in wheat and barley. Changes in weather conditions play an important role in FHB epidemics and dissemination, thus a systematic and long-term research approach is needed to provide effective forecasting and risk assessment models. This review discusses the history and epidemiology of FHB pathogens in wheat and barley at the global level, as well as potential plant defense mechanisms, the recent progress made in resistance breeding, and modern tools utilized in disease prediction. It also provides future directions for improving the management of the disease with these two important cereals.

Molecular pathology of forest trees for a long time lagged behind parallel studies on agricultural crop pathology. Recent technological advances have significantly contributed to the observed progress in this field. The first powerful impulse was provided by the completion of the black cottonwood genome sequence in 2006. Genomes of several other important tree species will be completed within a short time. Simultaneously, application of transcriptomics and next-generation sequencing (NGS) has resulted in the rapid accumulation of a vast amount of data on molecular interactions between trees and their microbial parasites. This review provides an overview of our current knowledge about these responses of forest trees to their pathogens, highlighting the achievements of the past decade, discussing the current state of the field, and emphasizing the prospects and challenges for the near future.

Fusarium head blight (FHB) is a major disease in wheat causing severe economic losses globally by reducing yield and contaminating grain with mycotoxins. In Canada, Fusarium graminearum is the principal etiological agent of FHB in wheat, producing mainly the trichothecene mycotoxin, deoxynivalenol (DON) and its acetyl derivatives (15-acetyl deoxynivalenol (15ADON) and 3-acetyl deoxynivalenol (3ADON)). Understanding the population biology of F. graminearum such as the genetic variability, as well as mycotoxin chemotype diversity among isolates is important in developing sustainable disease management tools. In this study, 570 F. graminearum isolates collected from commercial wheat crops in five geographic regions in three provinces in Canada in 2018 and 2019 were analyzed for population diversity and structure using 10 variable number of tandem repeats (VNTR) markers. A subset of isolates collected from the north-eastern United States was also included for comparative analysis. About 75% of the isolates collected in the Canadian provinces of Saskatchewan and Manitoba were 3ADON indicating a 6-fold increase in Saskatchewan and a 2.5-fold increase in Manitoba within the past 15 years. All isolates from Ontario and those collected from the United States were 15ADON and isolates had a similar population structure. There was high gene diversity (H = 0.803–0.893) in the F. graminearum populations in all regions. Gene flow was high between Saskatchewan and Manitoba (Nm = 4.971–21.750), indicating no genetic differentiation between these regions. In contrast, less gene flow was observed among the western provinces and Ontario (Nm = 3.829–9.756) and USA isolates ((Nm = 2.803–6.150). However, Bayesian clustering model analyses of trichothecene chemotype subpopulations divided the populations into two clusters, which was correlated with trichothecene types. Additionally, population cluster analysis revealed there was more admixture of isolates among isolates of the 3ADON chemotypes than among the 15ADON chemotype, an observation that could play a role in the increased virulence of F. graminearum. Understanding the population genetic structure and mycotoxin chemotype variations of the pathogen will assist in developing FHB resistant wheat cultivars and in mycotoxin risk assessment in Canada.

Fungal plant pathogens remain a serious threat to the sustainable agriculture and forestry, despite the extensive efforts undertaken to control their spread. White root rot disease is threatening rubber tree (Hevea brasiliensis) plantations throughout South and Southeast Asia and Western Africa, causing tree mortality and severe yield losses. Here, we report the complete genome sequence of the basidiomycete fungus Rigidoporus microporus, a causative agent of the disease. Our phylogenetic analysis confirmed the position of R. microporus among the members of Hymenochaetales, an understudied group of basidiomycetes. Our analysis further identified pathogen’s genes with a predicted role in the decay of plant cell wall polymers, in the utilization of latex components and in interspecific interactions between the pathogen and other fungi. We also detected putative horizontal gene transfer events in the genome of R. microporus. The reported first genome sequence of a tropical rubber tree pathogen R. microporus should contribute to the better understanding of how the fungus is able to facilitate wood decay and nutrient cycling as well as tolerate latex and utilize resinous extractives.