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Use of RAPD, enzyme activity staining, and colony size to differentiate phytopathogenic Fuzarium Oxysporum isolates from Iran

Uso de RAPD, coloração de atividade enzimática e tamanho de colônia para diferenciação de isolados fitopatogênicos de Fusarium oxysporum obtidos no Irã

Fusarium oxysporum is a common soilborn plant pathogen with a worldwide distribution. Fusarium yellows disease of chickpea (Cicer arientinum) caused by F.oxysporum is one of the most destructive soilborn disease which is a major production constraint in chickpea-growing regions of Iran. Three laboratory methods "amplification of genomic DNA using random primers, enzyme activity staining, and colony size determination" have been used to discriminate between highly virulent (HV) and weakly virulent (WV) isolates of F. oxysporum. On the basis of colony size (a traditional morphological method) and the ability of isolates to produce pectic enzymes, five HV isolates were differentiated from three WV isolates. The HV isolates formed large colony (ranging from 10.1 to 12.6 mm in diameter) and showed the same enzyme pattern,while the WV isolates produced small colony (ranging from 5.8 to 7.8 mm in diameter) and had not detectable enzyme activity in the stained overlaying gel. Twelve arbitrary 10-mer primers were tested on these 8 isolates of F. oxysporum by Polymerase Chain Reaction (PCR). Cluster analysis of the data from the DNA amplification by Random Amplified Polymorphic DNA (RAPD), differentiated HV from WV isolates. The results obtained from RAPD test confirmed the classification of these eight isolates based on pathogenicity test, colony size, and enzyme activity staining into two groups (HV and WV).

Fusarium oxysporum; RAPD; colony size; enzyme activity staining

Sociedade Brasileira de Microbiologia USP - ICB III - Dep. de Microbiologia, Sociedade Brasileira de Microbiologia, Av. Prof. Lineu Prestes, 2415, Cidade Universitária, 05508-900 São Paulo, SP - Brasil, Ramal USP 7979, Tel. / Fax: (55 11) 3813-9647 ou 3037-7095 - São Paulo - SP - Brazil