Diversity of Fusarium spp. associated with wheat node and grain in representative sites across the western Canadian Prairies

Abstract

Fusarium head blight (FHB) and Fusarium crown and root rot (FCRR) are major wheat diseases worldwide. In this study, wheat node and grain samples were collected from four representative sites across the western Canadian prairies in 2018 growing season to characterize the major Fusarium spp. and other mycobiota associated with wheat in these regions. In total, 994 fungal isolates were recovered and based on culture and molecular diagnostic methods, three genera constituted over 90% of all fungal isolates, these were Alternaria (39.6%), Fusarium (27.8%), and Parastagonospora (23.9%). A qPCR was developed to quantify the most frequently isolated Fusarium spp. in infected wheat tissues: F. avenaceum, F. culmorum, F. graminearum and F. poae. The qPCR specificity was validated in silico, in vitro and in planta and proved specific to the target species.. The qPCR results showed that F. graminearum was not detected frequently in the four tested locations in this study. F. poae was the most abundant Fusarium species in grain samples in all tested locations. However, in node samples, F. culmorum (Beaverlodge and Scott) and F. avenaceum (Lacombe and Lethbridge) were the most abundant species. Trichothecene genotyping, showed that the 3ADON is the most dominant trichothecene genotype (68%), followed by type-A trichothecenes (29.5%), while the 15ADON trichothecene genotype was least dominant (2.5%) and the NIV genotype was not detected. Moreover, a total of 129 TEF1α sequences from nine Fusarium spp. were compared at haplotype level to evaluate genetic variability and haplotype distribution. F. avenaceum and F.poae exhibited higher diversity.