''Rhizoctonia noxia'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Cantharellales The Cantharellales are an order (biology), order of fungi in the class (biology), class Agaricomycetes. The order includes not only the chanterelles (Cantharellaceae), but also some of the tooth fungi (Hydnaceae), clavarioid fungi (Aphelariaceae ...

Basidiocarps In fungi, a basidiocarp, basidiome, or basidioma () is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do no ...

(fruit bodies) are thin, effused, and web-like. The species is tropical to sub-tropical and is mainly known as a

plant pathogen Plant diseases are diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like orga ...

, the causative agent of "kole-roga" or black rot of

coffee Coffee is a beverage brewed from roasted, ground coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulating effect on humans, primarily due to its caffeine content, but decaffeinated coffee is also commercially a ...

and various blights of

citrus ''Citrus'' is a genus of flowering trees and shrubs in the family Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, mandarins, lemons, grapefruits, pomelos, and limes. ''Citrus'' is nativ ...

and other trees.

Taxonomy

The fungus responsible for kole-roga of coffee was sent from India to

Mordecai Cubitt Cooke Mordecai Cubitt Cooke (12 July 1825, in Horning, Norfolk – 12 November 1914, in Southsea, Hampshire) was an English botanist and mycologist who was, at various points, a London schoolteacher, a Kew mycologist, curator at the India Museum, jour ...

at the

Royal Botanic Gardens, Kew Royal Botanic Gardens, Kew is a non-departmental public body in the United Kingdom sponsored by the Department for Environment, Food and Rural Affairs. An internationally important botanical research and education institution, it employs 1,10 ...

who named it ''Pellicularia koleroga'' in 1876. Cooke, however, described only hyphae and some small warted spores, later presumed to be from a contaminating mould. As a result Donk, when reviewing ''Pellicularia'' in 1954, dismissed both the genus and ''P. koleroga'' as "nomina confusa", later (1958) substituting the new name ''Koleroga noxia'' for the species. Based on a re-examination of specimens, Roberts (1999) considered ''Koleroga'' to be a synonym of ''

Ceratobasidium ''Ceratobasidium'' is a genus of fungi in the order Cantharellales. Basidiocarps (fruit bodies) are effused and the genus is sometimes grouped among the corticioid fungi, though species also retain features of the heterobasidiomycetes. Anamorph ...

''.

Molecular A molecule is a group of two or more atoms that are held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemistry, ...

research, based on

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

analysis of

DNA sequences A nucleic acid sequence is a succession of bases within the nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. This succession is denoted by a series of a set of five different letters that indicate the order of the ...

, has, however, now placed ''Ceratobasidium'' species (excepting the

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * ...

) in synonymy with ''

Rhizoctonia ''Rhizoctonia'' is a genus of fungi in the family Ceratobasidiaceae. Species form thin, effused, corticioid basidiocarps (fruit bodies), but are most frequently found in their sterile, anamorph state. ''Rhizoctonia'' species are saprotrophic, ...

.'' means "rot disease" in the

Kannada Kannada () is a Dravidian language spoken predominantly in the state of Karnataka in southwestern India, and spoken by a minority of the population in all neighbouring states. It has 44 million native speakers, and is additionally a ...

language of

Karnataka Karnataka ( ) is a States and union territories of India, state in the southwestern region of India. It was Unification of Karnataka, formed as Mysore State on 1 November 1956, with the passage of the States Reorganisation Act, 1956, States Re ...

Description

Fruit bodies are effused, thin, and whitish. Microscopically they have colourless

hyphae A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

, 3 to 8

μm The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System ...

wide, without

clamp connection A clamp connection is a hook-like structure formed by growing hyphal cells of certain fungi. It is a characteristic feature of basidiomycete fungi. It is created to ensure that each cell, or segment of hypha separated by septa (cross walls), rece ...

s. The

basidia A basidium (: basidia) is a microscopic spore-producing structure found on the hymenophore of reproductive bodies of basidiomycete fungi. The presence of basidia is one of the main characteristic features of the group. These bodies are also ...

are ellipsoid to broadly club-shaped, 10 to 12 by 7 to 8 μm, bearing four

sterigma In biology, a sterigma (: sterigmata) is a small supporting structure. It commonly refers to an extension of the basidium (the spore-bearing cells) consisting of a basal filamentous part and a slender projection which carries a spore at the tip ...

ta. The

basidiospore A basidiospore is a reproductive spore produced by basidiomycete fungi, a grouping that includes mushrooms, shelf fungi, rusts, and smuts. Basidiospores typically each contain one haploid Ploidy () is the number of complete sets of chromos ...

s are narrow and fusiform, 9 to 13 x 3 to 5 μm.

Habitat and distribution

''Rhizoctonia noxia'' has only been collected as a plant pathogen on living stems and leaves of commercial crops (including coffee, citrus, and

persimmon The persimmon () is the edible fruit of a number of species of trees in the genus '' Diospyros''. The most widely cultivated of these is the Chinese and Japanese kaki persimmon, ''Diospyros kaki''. In 2022, China produced 77% of the world's p ...

) on which it causes a web blight. It has been reported from Asia (including India and Vietnam) and from the Americas (including Colombia, Guatemala, Jamaica, Puerto Rico, Trinidad, United States, and Venezuela).

References

{{Taxonbar, from=Q108321411 Fungal plant pathogens and diseases Cantharellales Taxa named by Marinus Anton Donk Fungi described in 1958 Fungus species