Submitted to: Mycological Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/1/2002
Publication Date: 9/1/2002
Citation: BON, M., FARGUES, J., MANGUIN, S., COUTEAUDIER, Y. GENETIC VARIABILITY AMONG PAECILOMYCES FUMOSOROSEUS ISOLATES FROM VARIOUS GEOGRAPHICAL AND HOST INSECT ORIGINS BASED ON THE RDNA-ITS REGIONS.. MYCOLOGICAL RESEARCH. 2002. Interpretive Summary: Problem. The silverleaf whitefly is a major pest of field and greenhouse crops. A fungus, Paecilomyces fumosoroseus, has been found that is pathogenic to these insects. Before the fungus can be considered for use in a commercial product, the strains need to be identified. Approach. 48 strains of the fungus were identified by using variable regions within their ribosomal RNA genes. These regions was digested using different enzymes, this generating multiple fragments of different lengths. The fragments were then compared among the different strains, and the following information was used to assess relatedness between the strains. Impact. The information on the identity and relatedness of the different strains is important for both commercial reasons, such as patenting a particular strain, and for scientific reasons, such as understanding the biology and diversity of a single species of fungus.
Technical Abstract: The entomopathogenic hyphomycete Paecilomyces fumosoroseus is a promising candidate for biocontrol of economically important agricultural pests. Assessment of genetic relatedness of this species appears to be essential to gain insights into the monitoring of such biocontrol products. Intraspecific variation within the internal transcribed spacer region of the ribosomal RNA gene (rDNA-ITS) was studied in 48 isolates of P. fumosoroseus . These strains were isolated from different geographical and biological origins, more particularly from the silverleaf whitefly, Bemisia tabaci-argentifolii (Homoptera: Aleyrodidae), a major insect pest in field and greenhouse crops. PCR amplification of the ITS1-5.8S-ITS2 rDNA region followed by restriction analysis of the PCR products underlined the overall highly variable nature of this region. Digestion with the six endonucleases AluI, HaeIII, Hin6I, HpaII, NdeII, and SmaI allowed the separation of the isolates into three distinct groups. The group 1, representing 25 isolates, is composed of strains isolated only from the host B. tabaci-argentifolii. By contrast, the group 3 is more diffuse as it included strains from various insect host and geographical origins. Phylogenetic analysis of rDNA-ITS sequence data strongly supported the conclusions of the PCR'RFLP analysis and recognized three monophyletic groups within the P. fumosoroseus complex. The high level of polymorphism within the P. fumosoroseus species is discussed in the light of their biological origin.