Anastomosis groups of multinucleate and binucleate Rhizoctonia

The genus Rhizoctonia, is a soil-borne plant pathogen with considerable diversity in cultural morphology, host range and aggressiveness. Despite its history as a destructive pathogen of economically important crops worldwide, our understanding of its taxonomic relationship with other Rhizoctonia-like fungi, incompatibility systems, and population biology is rather limited. The fusion of vegetative hyphae of same or two colonies belonging to same species is called hyphal anastomosis. Hence, the fungus sustains bidirectional transmission within, thus sharing dissolved ions, hormones and nucleotides. The fungal network might begin from many origins; many spores (i.e., by means of conidial anastomosis groups), various points of penetration, each spreading circumference of absorption and assimilation. Currently, there are several accepted classifications based on the anastomosis group (AG) concept for both multinucleate (Thanatephorus) and binucleate (Ceratobasidium) taxa within the Rhizoctonia species complex. Anastomosis grouping has not only served as the single most important criterion for delimiting isolates recognized as members of the species, but has also revealed that Rhizoctonia solani is a species complex consisting of non-interbreeding or reproductively isolated populations. This review mainly focuses on the various anastomosis groups of both multinucleate (Thanatephorus) and binucleate (Ceratobasidium) taxa within the Rhizoctonia species.