Characterization of Iranian Isolates of Fusarium oxysporum on the Basis of RAPD Analysis, Virulence and Vegetative Compatibility

Abstract

Fusarium yellow disease of chickpea (Cicer arietinum), caused by the vascular wilt pathogen Fusarium oxysporum, is a major production constraint in chickpea-growing regions of Iran. Fifteen isolates of F. oxysporum were classified on the basis of vegetative compatibility (the ability to form heterokaryons). Vegetative compatibility was assessed by pairing nit mutants. The isolates were assigned to three vegetative compatibility groups (VCGs): VCG1, VCG2, and VCG3 with 5, 3, and 7 members, respectively. These isolates were also characterized by virulence assay. On the basis of disease severity on chickpea seedlings, they were divided into three groups: highly virulent (HV), moderately virulent (MV) and weakly virulent (WV).Twelve arbitrary decamer primers were tested on the fungal isolates by polymerase chain reaction. Random amplified polymorphic DNA (RAPD) analysis indicated considerable genetic variation among these isolates. Comparison of the results of VCG tests and the virulence assay indicated that all seven HV isolates belong to a single vegetative compatibility group (VCG3), and all three WV isolates are placed in VCG1. There was no relationship between RAPD groups and the other two characteristics of Iranian F. oxysporum isolates.

Analysis of genotypic diversity inCercospora beticola Sacc. field isolates

“…Such an absence of correlation was also reported in other fungi like Fusarium oxysporum (Zamani et al, 2004) and Alternaria solani (Van der Waals et al, 2004). This could be an additional support that the primers used were really selectively neutral and thereafter suitable for population structure studies (Weising et al, 1995).…”

Fusarium wilt of chickpea: physiological specialization, genetics of resistance and resistance gene tagging

“…Despite monophyletic lineage, geographically isolated populations of the fungus displayed genetic and pathological diversity. The Iranian isolates comprised at least three vegetative compatibility groups (VCGs) (Zamani et al 2004) whereas the four Indian races were phylogenetically distinct from each other (Sivaramakrishnan et al 2002;Chakrabarti et al 2001; Barve et al 2001). Indian populations of pathogen were also genetically as well as pathologically distinct from those in other countries as is evident from DNA Wngerprinting studies (Barve et al 2001) and conWnement of races 1A, 2, 3 and 4 (wilting pathotypes) to the India and 0 and 1B/C (yellowing pathotypes) to the Mediterranean region and California.…”

Screening techniques and sources of resistance to root diseases in cool season food legumes

“…Chakrabarti et al (2001) reported that amplification of intergenic spacer (IGS) regions and digestion with restriction enzymes could be used to study polymorphism in Foc and proposed that races 1 and 4 are similar. Three VCGs were identified among 15 Iranian isolates of Foc; no correlation between RAPD patterns and virulence or geographic origin was observed (Zamani et al, 2004). Pathotype-specific primer pairs based on a sequencecharacterized amplified region (SCAR) derived from a RAPD sequence which was unique for "wilting" Foc isolates was designed and used for in planta detection (Kelly et al, 1998).…”