Genetic Variation Among Vegetative Compatibility Groups of Fusarium oxysporum f. sp. cubense Analyzed by DNA Fingerprinting

Abstract

Genetic variation within a worldwide collection of 208 isolates of Fu-sarium oxysporum f. sp. cubense, representing physiological races 1, 2, 3, and 4 and the 20 reported vegetative compatibility groups (VCGs), was analyzed using modified DNA amplification fingerprinting. Also characterized were 133 isolates that did not belong to any of the reported VCGs of F. oxysporum f. sp. cubense including race 3 isolates from a Heliconia species and isolates from a symptomatic wild banana species growing in the jungle in peninsular Malaysia. The DNA fingerprint patterns were generally VCG specific, irrespective of geographic or host origin. A total of 33 different genotypes were identified within F. oxysporum f. sp. cu-bense; 19 genotypes were distinguished among the isolates that belonged to the 20 reported VCGs, and 14 new genotypes were identified among the isolates that did not belong to any of the existing VCGs. DNA fingerprinting analysis also allowed differentiation of nine clonal lineages within F. oxysporum f. sp. cubense. Five of these lineages each contained numerous closely related VCGs and genotypes, and the remaining four lineages each contained a single genotype. The genetic diversity and geographic distribution of several of these lineages of F. oxysporum f. sp. cubense suggests that they have coevolved with edible bananas and their wild diploid progenitors in Asia. DNA fingerprinting analysis of isolates from the wild pathosystem provides further evidence for the coevolution hypothesis. The genetic isolation and limited geographic distribution of four of the lineages of F. oxysporum f. sp. cubense suggests that the pathogen has also arisen independently, both within and outside of the center of origin of the host.

Identification of Volatile Metabolites from Fungal Endophytes with Biocontrol Potential towards <i>Fusarium oxysporum</i> F. sp. <i>cubense</i> Race 4

“…The fungal pathogen Fusarium oxysporum F. sp. cubense race 4 (FocR4) from VCG 01213/16 (Bentley et al, 1998) Detection of inhibitory activity by volatiles produced by fungal endophytes: Double-plate assay was performed to determine the inhibitory potential of fungal endophytes towards FocR4 via production of volatile inhibitory metabolites. The fungal cultures (including FocR4) were first established as pure cultures on PDA plates for 5 days.…”

Molecular variation among isolates of Fusarium species

“…Previous studies conducted on worldwide populations of Fusarium included PCR methods such as RAPD analysis (Bentley and Dale 1995), DNA amplification fingerprinting (DAF) (Bentley et al 1998 andGerlach et al 2000), RFLPs (Koenig et al 1997), DNA sequence analysis (Geiser et al 2004) and IRAP marker (Arabi and Jawhar 2010). Although these techniques were able to provide knowledge related to the genetic diversity in Fusarium, but they did not always agree in terms of genetic relationships among clonal lineages of this asexually reproducing pathogen.…”

Occurrence of Tropical Race 4 of Fusarium oxysporum f. sp. cubense in Indonesia

“…In Asia, fusarium wilt is widespread in many countries such as India, Indonesia, Malaysia, Taiwan, and the Philippines (Bentley et al, 1998). Fusarium wilt of banana was first reported in Indonesia in 1916 from banana plantations in Java (Stover, 1962a) and has since been found to be widespread in many banana production areas of Indonesia.…”

“…cubense with the number of VCGs being greatest in Asia where it is believed that F. oxysporum f. sp. cubense evolved (Bentley et al, 1998). Other criteria have been used to identify variation within F. oxysporum f. sp.…”

“…The rest did not form heterokaryons with all nitM VCG testers used and classified as VCG unknown (Table 1). Bentley et al (1998) stated that isolates were classified as VCG unknown either because they had not yet been typed by VCG analysis prior to DNA finger printing or they were not compatible with the available set of nitM testers representing the 20 currently recognized VCGs. Bnt2,Mln1,Srg1,Bgl6,Bgl3,Lmp1,Kjg1,A13,Pjn4,Gnk3,and Wsb5) and other 3 odoratum (Btu3, Tmg1, and Bnt1) isolates were grown in 40 mL of potato dextrose broth (Burgess et al, 1994) in 100 mL Erlenmeyer flasks and shaken at 100 rpm at 28 o C for 7 days.…”