AMPLIFICATION AND DIRECT SEQUENCING OF FUNGAL RIBOSOMAL RNA GENES FOR PHYLOGENETICS

Abstract

Fusarium oxysporum f. sp.cubense (Foc), is the causal agent of the disease known as Fusarium wilt in musaceous crops.It is one of the major limiting factors in the world production of banana and plantain.In Colombia, genetic information on the phytopathogen is scarce and after the problem presented in the 1950s that affected the cultivar Gros Michel, this work was aimed at making a morphological and genetic characterization of various isolates of Fusarium acquired from a sampling of banana and plantain crops in 11 departments of Colombia.For this purpose, 121 symptomatic samples were processed from which 89 isolates were obtained to form a bank of strains, which were morphologically and genetically characterized, amplifying and sequencing the genes (Internal Transcribed Spacer Internal Transcript) ITS, (Elongation Factor 1 α) EF 1α and (Second long subunit of RNA polymerase) RPB2.Of these isolates, 88 showed breeding and resistance structures typical of the genus Fusarium and the genetic identity of the strains was corroborated by amplification of a specific fragment of the ITS region with the ITS FU primers for the genus of interest and simultaneously, 54 isolates were determined as Fusarium oxysporum f. sp.cubense (Foc).In addition, amplifications of the molecular markers confirmed that the fungi were related to the genus and the esecie complex Fusarium oxysporum (FOSC) and even the species complexes Fusarium fujikuroi (FFSC), Fusarium solani (FSSC) and Fusarium incarnatum-equiseti (FIESC) were found.The study was only able to differentiate between species complexes commonly found in musacaea cultures, because the primers are not sufficiently informative to discern between the races referred to for the cubense special form, but to trace the presence of 6 genetically different Foc haplotypes distributed in Colombia, which should be evaluated by infection in plants to establish their pathogenicity.

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