Distinct electrophoretic isozyme profiles of Fusarium graminearum and closely related species

Rapid identification of clinical Trichoderma longibrachiatum isolates by cellulose-acetate electrophoresis-mediated isoenzyme analysis

Cellulose-acetate electrophoresis was used to investigate isoenzyme polymorphism among ten clinical and 11 non-clinical isolates of Trichoderma. Initial testing of 13 enzyme systems for activity and resolution of bands showed that seven were appropriate for identifying the different species. Each of the enzyme systems investigated (glucose-6-phosphate dehydrogenase, glucose-6-phosphate isomerase, 6-phosphogluconate dehydrogenase, peptidases A, B and D, and phosphoglucomutase) was diagnostic for at least one species. On the basis of the results of isoenzyme analysis, several isolates identified originally as Trichoderma pseudokoningii, T. koningii or T. citrinoviride were re-identified as T. longibrachiatum, in agreement with sequence analysis data for the internal transcribed spacer region of the isolates. The availability of a quick, inexpensive and reliable diagnostic tool for the identification of T. longibrachiatum isolates is important, as most clinical Trichoderma isolates belong to T. longibrachiatum. Furthermore, as many different enzyme systems are available, the method may also be suitable for the identification of other clinically relevant fungal species.

Analysis of rDNA ITS sequences to determine genetic relationships among, and provide a basis for simplified diagnosis of, Fusarium species causing crown rot and head blight of cereals

Genetic relationships of the complex of Fusarium species associated with crown rot and head blight in cereals and some species associated with plant diseases in general were examined by distance and maximum parsimony algorithms of their internal transcribed spacer sequences. The analysis clustered the complex of Fusarium species that causes root and crown rot and head blight of cereals and three other clusters of F. sambucinum, F. venenatum and F. poae into one clade. This group of Fustarium species was also found in this study to correspond to the group defined by the presence of the tri5 gene. The tri5 gene was recently reported to co-segregate with the locus governing the type of trichothecene produced, and probably maps in the trichothecene gene cluster. The other clusters of F. avenaceum, F. tricinctum, F. torulosum, F. oxysporum, F. verticillioides and F. solani did not have the tri5 gene. Although, F. pseudograminearum was phylogenetically close with the cluster of F. graminearum, F. culmorum and F. cerealis, it could be distinctly separated from them. The distinct genetic status of F. pseudograminearum from F. graminearum corroborated with other published molecular data and isozyme findings. The molecular analysis provided a simple diagnostic tool to differentiate fungi causing crown rot from those involved in head blight.

Identification of Fusarium species by isozyme analysis

Cellulose-acetate electrophoresis (CAE) was used to investigate isozyme polymorphisms among different isolates of Fusarium cerealis, F. culmorum, F. graminearum and F. pseudograminearum. After initial testing of 18 enzymes in three buffer systems for activity and resolution of bands, 12 proved to be appropriate for analysis of the full sample set. Comparing the different electrophoretic types (ETs), adenylate kinase (AK), NADP dependent glutamate dehydrogenase (NADP GDH), peptidase B (PEP B), peptidase D (PEP D) and phosphoglucomutase (PGM) proved to be diagnostic for at least one species examined. However, only PEP D was useful alone as a marker to distinguish the four taxa studied providing a rapid and simple CAE based diagnostic protocol.