Estudo da diversidade genética de isolados de Fusarium oxysporum f. sp. cubense por meio de técnicas moleculares

Abstract

Bananas (Musa sp.) are the most consumed fruit in the world and they are primarily grown in tropical countries. One of the main causes for reduction in banana production is the onset of fusariosis, disease caused by the fungus Fusarium oxysporum f.sp. cubense, which can compromise up to 100% of the production. The fusariosis is best controlled through the development of resistant hybrid varieties. However, before such strategy is used it becomes necessary to know a great deal about the variability of the pathogen. The aim of this paper was to study the genetic variability of F. oxysporum f. sp. cubense samples from different geographical areas, using RAPD, RFLP-PCR markers from the ITS and IGS regions, including a sequence from the ITS region of the rDNA. The use of nine primers in the RAPD reactions has produced 61 bands, all polymorphic, as an example of the high variability of the pathogen. No relation has been found between the groupings based on the RAPD and the geographical sources of the isolated groupings. On the other hand, the PCR-RFLP technique has proved to be less useful to determine genetic variability, especially in the case of the ITS region. The sequencing data have indicated fragments ranging from 517 to 557 nucleotides with high similarity (96 to 98 %). The sequences obtained also revealed great similarity with sequences from other isolated Fusarium spp. Stored in the Genbank