Review. Biology and systematics of the form genus Rhizoctonia

Abstract

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 Kühn), 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.Additional key words: Basidiomycetes, biocontrol, Ceratobasidiaceae, Ceratobasidium, fungal diseases, methodology, taxonomy, Thanatephorus. Resumen Biología y Sistemática del género forma RhizoctoniaLos miembros del género forma Rhizoctonia D.C. son considerados como un complejo de hongos filamentosos, presentando en común una fase asexual no productora de esporas, denominada anamorfo tipo Rhizoctonia. El grupo incluye algunos importantes patógenos como Thanatephorus cucumeris (Frank) Donk (anamorfo=Rhizoctonia solani Kühn), la mayoría de especies micorrícicas de orquídeas (principalmente del género Ceratobasidium D.P. Rogers), y algunos taxones de posición taxonómica variada. El anamorfo tipo Rhizoctonia es definido por una serie de características, presentes y comunes en todos los taxones del complejo. Los taxones del grupo han sido distribuidos entre varios grupos de hongos, incluyendo Ascomicetes y Basidiomicetes, y reubicados en varios géneros de ambas clases, empleando criterios de clasificación tales como el análisis y comparación de la ultraestructura del aparato septal. Habitualmente, la clasificación en algunos de los grupos del complejo ha estado basada en la aplicación de criterios tales como la anastomosis hifal, debido a que en este tipo de hongos es escasa la presencia de un número aceptable de caracteres diagnósticos. Los trabajos ...

Bacillus amyloliquefaciens subsp. plantarum GR53, a potent biocontrol agent resists Rhizoctonia disease on Chinese cabbage through hormonal and antioxidants regulation

“…Of particular consequence is the damping-off in cabbage seedlings caused by the fungus Rhizoctonia solani, which is a major challenge to manage and control (Shiau et al 1999). More generally, the fungus can persist as sclerotia for several years in the soil and causes diseases in a wide range of their host plants (Gonzalez-Garcia et al 2006). Soil fumigation is the current strategy used to manage crop diseases, but it also negatively affects beneficial soil microorganisms that assist crop growth (Solanki et al 2012).…”

Isolated Bacillus subtilis strain 330-2 and its antagonistic genes identified by the removing PCR

“…Rhizoctonia solani Kühn (teleomorph: Thanatephorus cucumeris (Frank) Donk) is one of the most prevalent soil-borne pathogen, which causes a significant economic losses in several economically important crops such as maize, rice and soybean 17 . Banded leaf and sheath blight (BLSB), caused by R. solani , is the most threatening disease, which may cause complete crop failure 18 .…”

Effects of Bacillus amyloliquefaciens FZB42 on Lettuce Growth and Health under Pathogen Pressure and Its Impact on the Rhizosphere Bacterial Community

“…Soil-borne plant pathogens like Rhizoctonia solani Kühn [anamorph, teleomorph: Thanatephorus cucumeris (Frank) Donk] are difficult to control [1], [2]. Members of this species can survive as sclerotia for long periods in the soil.…”