Caracterização molecular e morfológica de isolados de Colletotricuhm spp. associadas ao feijoeiro

Abstract

In common bean, the genus Colletotrichum is among the economically important phytopathogen groups for the crop. Several species of Colletotrichum have been isolated from common bean. Molecular techniques have been used as an alternative in the identification of phytopathogens. The REP PCR technique has been used in studies of genetic variability by obtaining fingerprints for fungi and may be a promising alternative in the differentiation of fungi of the genus Colletotrichum. The objective of this work is to characterize Colletotrichum spp isolates from common bean using Rep-PCR markers and to verify the occurrence of "switching" of minus and plus colonies. Isolates of C. lindemuthianum, C. soyae, C. karstii and C. plurivorum were used. Molecular analysis was performed using the Rep-PCR technique using BOX, ERIC and REP primers to obtain a fingerprint. The morphological characterization was carried out regarding the type of colony. The sexual compatibility test between the isolates was performed. All primers used in this study were able to amplify genomic DNA and generate band profiles with reproducibility for all isolates tested. The BOX marker revealed a very low amount of polymorphism, which made it impossible to differentiate the species using this marker. The ERIC marker generated polymorphism, but in an amount that was also insufficient to configure the efficient differentiation of these species. Taking into account the species under study, it can be observed that only the REP marker was able to detect interspecific polymorphism and that they presented better results. In the analysis of sexual compatibility, only the combinations UFLA 13-1A x UFLA13-2A and UFLA13-1A x UFLA15-5 promoted the formation of perithecia with asci and ascospores in the contact line between the colonies, suggesting sexual compatibility. The progenies from the cross between UFLA13-1A and UFLA13-2A in the molecular analysis, confirmed the data of the individual analysis of each parent, that is, both parents showed the same profile for all the markers used. Therefore, these markers are not suitable for verifying the occurrence of outcrossing between these isolates. However, the REP primer reproduced a band pattern in the progenies of both parents, for the contact line formed between UFLA 13-1A and UFLA 15-5, which are present in all progenies, evidencing the occurrence of crossing between these isolates. The technique using the REP primer allowed the differentiation between the evaluated isolates and evidenced the occurrence of crossing. The presence of plus and minus peritetial colonies, and conidials evidence the occurrence of a change from plus to minus in the UFLA 13-A1 isolate in monoculture and in crosses with UFLA15-5.