TRICHOTHECENE GENOTYPES OF FUSARIUM GRAMINEARUM SPECIES COMPLEX AND F CROOKWELLENSE ISOLATES FROM MEXICAN CEREALS
M. Osman, X. He, S. Benedettelli, P.K. Singh
Four of the world’s most important crops, wheat, barley, rice and maize, in addition to other small grains are susceptible to Fusarium graminearum species complex (FGSC), the most important causal agent of Fusarium head blight (FHB). The major threat from this species complex comes from trichothecene mycotoxins such as deoxynivalenol (DON) and nivalenol (NIV) and their acetylated derivatives, including 3-acetyldeoxynivalenol (3-ADON), 15- acetyldeoxynivalenol (15-ADON), and 4-acetylnivalenol (4-ANIV). Polymerase chain reaction (PCR) assays are being utilized to quickly identify type B trichothecene genotypes in populations of head blight causing Fusaria. In the current study, 388 isolates collected from different locations in 6 Mexican states between 1995 and 2013 were analyzed by chemotype and sub-chemotype specific markers. It was found that the disease has been predominantly caused by FGSC, while F. crookwellense co-presented as FHB causal agent in Mexico. Both DON and NIV trichothecene genotypes were identified in isolates belonging to FGSC, with the DON genotype predominating. Furthermore, all DON isolates were shown to be the 15- ADON genotype and no 3-ADON genotype was identified. This was the first detailed study on the trichothecene genotypes of Mexican toxigenic Fusarium strains on large scale; wherein we report for the first time the occurrence of FGSC isolates belonging to NIV trichothecene genotype in Mexico.