Variabilité des alpha-estérases et de la virulence au sein de populations de l'Hyphomycète entomopathogène Beauveria bassiana (Bals.) Vuillemin isolées de populations larvaires d'Ostrinia nubilalis (Hübner)

Tigano Myrian S., Riba Guy, Aioun Agnès. Variabilité des alpha-estérases et de la virulence au sein de populations de l'Hyphomycète entomopathogène Beauveria bassiana (Bals.) Vuillemin isolées de populations larvaires d'Ostrinia nubilalis (Hübner). In: Bulletin de la Société entomologique de France, volume 95 (1-2), juin 1990. pp. 39-47

Variabilité des alpha-estérases et de la virulence au sein de populations de l'Hyphomycète entomopathogène Beauveria bassiana (Bals.) Vuillemin isolées de populations larvaires d'Ostrinia nubilalis (Hübner)

Tigano Myrian S., Riba Guy, Aioun Agnès. Variabilité des alpha-estérases et de la virulence au sein de populations de l'Hyphomycète entomopathogène Beauveria bassiana (Bals.) Vuillemin isolées de populations larvaires d'Ostrinia nubilalis (Hübner). In: Bulletin de la Société entomologique de France, volume 95 (1-2), juin 1990. pp. 39-47

Genetic diversity of Hirsutella thompsonii isolates from Thailand based on AFLP analysis and partial beta-tubulin gene sequences

Amplified fragment length polymorphism (AFLP) was used to investigate polymorphism among 43 Hirsutella thompsonii isolates (33 from Thailand) obtained from various mite species. The outgroups were an unidentified Hirsutella isolate along with Hirsutella nodulosa and Hirsutella kirchneri. Phylogenetic analyses of the AFLP data showed significant variation among isolates and the existence of three H. thompsonii clades. We also investigated the isolates using PCR with specific primers for the Hirsutella exotoxin gene Hirsutelin A (HtA) and 18 of these isolates were used for sequencing of the partial beta-tubulin gene. Phylogenetic analyses of beta-tubulin sequences showed two distinct H. thompsonii clades, one of which included AFLP clades I and II. For both markers grouping of the H. thompsonii isolates was not related to either host mite species or geographical origin, although for the HtA gene one clade contained only isolates with no detectable HtA band. These results confirm the high intraspecific polymorphism of H. thompsonii, and maximum likelihood analysis showed no monophyletic group within this species. To refine the taxonomy of this genus other studies should be undertaken using additional molecular markers and several other Hirsutella isolates

Transformation of the entomopathogenic fungi, paecilomyces fumosoroseus and paecilomyces lilacinus (deuteromycotina: hyphomycetes) to benomyl resistence

The entomopathogenic fungi Paecilomyces fumosoroseus and P. lilacinus have been transformed to resistance to the fungicide benomyl by a polyethylene glycol (PEG)-mediated procedure using a mutant b-tubulin gene from Neurospora crassa carried on plasmid pBT6. Benomyl-resistant transformants of P. lilacinus were obtained that could tolerate greater than 30 µg/ml benomyl and P. fumosoroseus transformants were obtained that could tolerate 20 µg/ml benomyl. Following 5 serial passages of transformants on benomyl-containing media and 5 serial passages on non-selective media, 100% of P. lilacinus transformants were found to be mitotically stable by a conidial germination test. In contrast, only 4 out of 9 transformants of P. fumosoroseus were mitotically stable. Southern blot analysis of genomic DNA from both species suggested that the mechanism of transformation in all transformants was by gene replacement of the b-tubulin allele. Non-homologous vector sequences were not detectable in the genomes of transformants.Os fungos entomopatogênicos Paecilomyces fumosoroseus e P. lilacinus foram transformados com o plasmídio pBT6, contendo o gene de b-tubulina modificado, isolado do fungo Neurospora crassa, o qual confere resistência ao fungicida benomil. Transformantes resistentes ao benomil, obtidos da P. lilacinus, apresentaram tolerância a concentrações superiores a 30 mg/ml, enquanto transformantes da P. fumosoroseus apresentaram tolerância a 20 mg/ml. Após 5 passagens seriadas dos transformantes em meio contendo benomil e 5 passagens seriadas em meio não seletivo, 100% dos transformantes da P. lilacinus apresentaram estabilidade mitótica, através do teste de germinação de conídios. Em contraste, somente 4 dos 9 transformantes obtidos para P. fumosoroseus foram mitoticamente estáveis. Análise de Southern blot dos DNA genômicos de ambas as espécies sugere que o mecanismo de transformação foi por substituição alélica do gene de b-tubulina, para todos os transformantes obtidos. As seqüências não homólogas do vetor não foram detectadas nos genomas dos transformantes