The use of vegetative compatibility tests for identification of biodiversity of phytopathogenic fungi

Abstract

SUMMARYVisual assessment of phenotypes, performed when two strains of one fungal species are cultivated in a mixed culture on specific media, is known as vegetative or heterokaryotic compatibility or incompatibility test, which enables identification of fungal clones and their classification based on phylogenetic groups. Hyphae of strains that have identical alleles at all vic loci can anastomose into a form of a visible heterokaryon. Strains that divide compatible loci and can anastomose each other belong to a subpopulation termed the vegetative compatibility group (VCG), which is genetically distinguishable from other VCGs. Each VCG is specific regarding its host plant or related host groups and can, but does not have to be virulent on other hosts.Vegetative compatibility can be established in different ways, but complementary auxotrophic strains or strains formed by spontaneous mutation during nutrition, capable of forming a prototrophic heterokaryon are predominantly used. The nit mutants are considered excellent genetic markers for determination of vegetative compatibility and grouping of strains or clones of one fungus into the same or different VCGs. The ability only to determine whether strains are the same or not, but not the degree of their relatedness using VCG, is a limiting factor in analyses that could be performed. VCGs are the most efficient when they are employed to detect the presence of a specific strain in a population.This paper provides an overview of the importance of the phenomenon of vegetative compatibility. Vegetative compatibility is one of the most important genetic traits in ascomycetes by which one subpopulation can be identified as a distinct genetic group. Furthermore, the procedures for isolation, identification and determination of nit mutant phenotypes, and for identification of complementary strains and VCGs are described in detail.

Potential of Atoxigenic Aspergillus flavus Vegetative Compatibility Groups Associated With Maize and Groundnut in Ghana as Biocontrol Agents for Aflatoxin Management

“…Apart from being the least competitive isolate, we were unable to obtain a complementary pair of nit auxotrophs for this isolate. Whether this isolate is self-incompatible as reported in studies of Aspergillus and other genera (Correll et al, 1987; Krnjaja et al, 2013) needs to be clarified. Consequently, frequencies of AAV GHG183-7 were not evaluated even though an isolate of that AAV was a constituent of experimental product B.…”

Heterokaryosis and diploid formation among Brazilian isolates of Macrophomina phaseolina

“…Vegetative compatibility analysis is a very useful tool for analysing pathogenic and nonpathogenic fungal populations and for identifying new races in crop production areas or regions or among host genotypes (Mpofu & Rashid, ; Krnjaja et al ., ). Because vegetatively compatible isolates have the same allele at each and every incompatibility locus, isolates of similar pathogenicity may belong to the same VCG (Dervis et al ., ; Krnjaja et al ., ).…”

“…Vegetative compatibility analysis is a very useful tool for analysing pathogenic and nonpathogenic fungal populations and for identifying new races in crop production areas or regions or among host genotypes (Mpofu & Rashid, ; Krnjaja et al ., ). Because vegetatively compatible isolates have the same allele at each and every incompatibility locus, isolates of similar pathogenicity may belong to the same VCG (Dervis et al ., ; Krnjaja et al ., ). Therefore, in plant disease diagnosis, the pairing of an unknown pathogenic fungus with a tester strain belonging to a known VCG provides a faster and simpler way to determine the identity of the infecting fungus compared to traditional pathogenicity tests using standard differential host species or cultivars (Leslie, ).…”

Exploring Anastomosis of Hyphae and Mating-Type Compatibility of Pochonia chlamydosporia Isolates of the Meloidogyne, Heterodera and Globodera Biotypes

“…According to Krnjaja et al [26], vegetative or heterokaryon compatibility or incompatibility tests refer to 'visual assessment of phenotypes' of two strains of one fungal species cultivated in a mixed culture on a specific medium, which enables identification of fungal clones. Hyphae of different isolates that are compatible can anastomose, fuse and exchange cytoplasmic or nuclear content to form a viable heterokaryon.…”