Members of the form genus Rhizoctonia D.C. are considered as a complex mixture of filamentous fungi, having in common the possession of a non-spored imperfect state, usually referred to as the Rhizoctonia anamorph. The group includes several of the most devastating crop pathogens like Thanatephorus cucumeris (Frank) Donk (anamorph=Rhizoctonia solani Kuhn), the majority of orchid mycorrhizal symbionts (mainly belonging to genus Ceratobasidium D.P. Rogers) and a collection of saprotrophic organisms of different systematic placement. The Rhizoctonia anamorph is characterized by several common features present among members of the entire Rhizoctonia species complex. Taxa from the group have been rearranged into several groups of higher fungi, including both Ascomycota and Basidiomycota, and split into several genera, employing criteria such as the analysis and ultrastructural comparison of septal apparatus. Until very recently, classification for some of the groups within the complex has been exclusively based on criteria such as hyphal anastomosis, since other types of diagnostic features are usually scarce in these fungi. Phytopathological studies in the complex have represented the major contingent of contributions in the group, especially in the case of R. solani. Some members of the complex have been reported to be protective isolates against pathogenic members of Rhizoctonia and some other fungal pathogens. This review focuses on the knowledge of several aspects of the species of Rhizcotonia s. lato, such as its current taxonomic placement, the biology and systematics of some groups of the complex, and a revision of the methodologies employed in studying it.

http://digital.csic.es/bitstream/10261/15813/3/Rhizoctonia.pdf

Review. Biology and systematics of the form genus Rhizoctonia

To initiate a conservation program of the Orchidaceae from the Brazilian Atlantic rain forest with the purpose of ex situ conservation or reintroduction in the State of Minas Gerais, seven mycorrhi...

/pdf/morphological-and-molecular-characterization-of-mycorrhizal-2lww5f2dnw.pdf

Morphological and molecular characterization of mycorrhizal fungi isolated from neotropical orchids in Brazil

(1982). Rapid Nuclear Staining of Rhizoctonia Solani and Related Fungi with Acridine Orange and with Safranin O. Mycologia: Vol. 74, No. 1, pp. 145-149.

Rapid Nuclear Staining of Rhizoctonia Solani and Related Fungi with Acridine Orange and with Safranin O

The single-spore progeny of an isolate of Rhizoctonia solani showed a wide range of cultural types. When these progeny were paired by plating on opposite sides of Petri plates or by mixing semiliquid cultures, certain combinations gave rise to heterokaryons. The heterokaryons originated from hyphal anastomoses and were culturally distinct from either of the contributing homokaryons. Observations suggested a bipolar coaipatibility mechanism among the homokaryons. Some homokaryotic strains fruited, yielding culturally indistinguishable progeny. These homothallic lines also formed heterokaryons with other homothallic lines. The progeny of these heterokaryons showed a wide range of cultural types, indicating that some homokaryons could fruit either homothallically or heterothallically.

Synthesis of heterokaryons in rhizoctonia solani kühn

Epulorhiza epiphytica sp. nov. isolated from mycorrhizal roots of epiphytic orchids in Brazil

The nuclear phenomena in the basidium of Ceratobasidium praticolum (Pellicularia praticola), studied by the Giemsa technique, are described and illustrated with photographs. The cells of the vegetative hyphae are multinucleate and those of the hymenia binucleate. Before fusion the two nuclei in the young basidium become closely adjacent, and their chromosomes are differentiated as elongated threads in two distinct groups. After the association of the karyolymph of the two nuclei, the chromosomes come into contact and pair. The diploid nucleus then undergoes meiosis. The haploid chromosome number is about six, with six bivalents present at the first meiotic (disjunctional) division. Apparent chromatid bridges were observed at anaphase I. The second meiotic division is equational. The spindle axis during both these divisions may be longitudinal, transverse, or oblique. The mature basidium has four nuclei which migrate through sterigmata into the basidiospores. Most of the basidiospores are uninucleate when ...

H. K. Saksena

Papers

Nuclear phenomena in the basidium of ceratobasidium praticolum (kotila) olive