BOX-PCR- and ERIC-PCR-based genotyping and phylogenetic correlation among Fusarium oxysporum isolates associated with wilt disease in Psidium guajava L.

Fusarium oxysporum f. sp. psidii is a soilborne fungal pathogen that causes wilt disease in guava. There is an urgent need to establish a sensitive and specific molecular assay to diagnose the disease. A genetic fingerprint of the guava wilt pathogen also needs to be established. We isolated and identified 21 isolates of F. oxysporum f. sp. psidii from soil and infected roots of wilted guava, from different agro-climatic regions of India. We used BOX-PCR and enterobacterial repetitive intergenic consensus (ERIC)-PCR for generating a genetic fingerprint of F. oxysporum f. sp. psidii that ranged from 150 to 2500 bp in size. A dendrogram was constructed for the isolates on the basis of both the fingerprint patterns and the highest and lowest similarity values. The latter were observed for Fop123–Fop127 (at 94.0%) and Fop18–Fop24 (at 18.0%), respectively. Molecular data were derived from an analysis of the internal transcribed spacer sequences of 38 isolates belonging to 19 taxa within the species F. oxysporum. In this study, F. oxysporum f. sp. psidii was grouped in a single cluster that represented a different genetic structure. This study suggests that BOX-PCR and ERIC-PCR could be suitable, rapid, reproducible, and useful techniques for the discrimination of F. oxysporum f. sp. psidii, to better manage guava wilt disease.