Characterization of Mycorrhizal Isolates of <i>Rhizoctonia solani</i> from an Orchid, Including AG-12, a New Anastomosis Group

Carling, D. E.; Pope, Elizabeth J.; Brainard, K. A.; Carter, D. A.

doi:10.1094/phyto.1999.89.10.942

Cited by 115 publications

(63 citation statements)

References 22 publications

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“…In the first group of taxa, 14 anastomosis groups have been described (Table 2) (Carling et al, 1999(Carling et al, , 2002a, including 13 different groups (named from AG 1 to AG 13) whose members are generally only capable of fusing hyphae among themselves. There is another anastomosis group named AG BI («bridging isolate») that includes isolates capable of fusing hyphae among themselves and also with members of other AG.…”

Section: Biology Of Rhizoctonia Speciesmentioning

confidence: 99%

Review. Biology and systematics of the form genus Rhizoctonia

García¹,

Onco

Susan

2006

Span. j. agric. res.

202

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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 ...

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Section: Biology Of Rhizoctonia Speciesmentioning

confidence: 99%

Review. Biology and systematics of the form genus Rhizoctonia

García¹,

Onco

Susan

2006

Span. j. agric. res.

202

View full text Add to dashboard Cite

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“…Isolates can exist as multinucleate homokaryons or heterokaryons and present diverse mating strategies (homothallic or heterothallic) (González et al, 2012). Phaseolus vulgaris isolates belong mainly to AG 1 (6 subgroups), AG 2 (4 subgroups) and AG 4 (Carling, 1996;Schneider et al, 1997;Carling et al, 1999;Carling et al, 2002;Godoy-Lutz et al, 2003;GodoyLutz et al, 2008;González et al, 2006). When evaluated on the same plant species, virulence between AGs varies from highly virulent to non-virulent.…”

Section: Introductionmentioning

confidence: 99%

Virulence and molecular characterization of Costa Rican isolates of Rhizoctonia solani from common bean

Mora-Umaña¹,

Barboza²,

Alvarado³

et al. 2013

Trop. plant pathol.

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Web blight is one of the main diseases that affects bean (Phaseolus vulgaris) cultivation. It infects diverse organs at any growth stage of the plant and can be present at different altitudes in a humid tropical climate. The causal agent of this disease is Thanatephorus cucumeris in its sexual stage and Rhizoctonia solani in the anamorph. The objective of this investigation was to characterize molecular isolates of R. solani obtained from bean plants from diverse production regions in Costa Rica and determine their virulence. Fifty-one samples of symptomatic bean plants were collected using a global positioning system. Virulence was evaluated using the detached leaf technique. Isolates were identified using AG 1-IA, AG 1-IB, AG 1-IC, AG 1-ID, AG 2-2, AG 2-2IIIB, AG 2-2IV and AG 4 molecular markers. ITS sequences were obtained and analyzed with BLAST, aligned, and a phylogenetic tree was constructed. A high degree of virulence and genetic variability between isolates was identified and the anastomosis subgroups of isolates were independent of their geographical origin.

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“…Strains belonging to the AG-1, AG-2, AG-3, AG-4 and AG-8 are particularly important pathogens that cause devastating diseases such as stem canker, foliage lesions or damping off in many crops (Sneh et al 1996;Schillinger and Paulitz 2006). On the other hand, some strains of R. solani exist merely as saprotrophs in soil (Ogoshi 1996) and AG-12 displays mycorrhizal interactions with orchids (Bernard 1909;Carling et al 1999). The sexual (teleomorphic) stage of R. solani [Thanatephorus cucumeris (Frank) Donk; Basidiomycota, family Ceratobasidiaceae] has little significance as a plant pathogen (Sneh et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Evolutionary Diversification Indicated by Compensatory Base Changes in ITS2 Secondary Structures in a Complex Fungal Species, Rhizoctonia solani

et al. 2009

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The rRNA cistron (18S-ITS1-5.8S-ITS2-28S) is used widely for phylogenetic analyses. Recent studies show that compensatory base changes (CBC) in the secondary structure of ITS2 correlate with genetic incompatibility between organisms. Rhizoctonia solani consists of genetically incompatible strain groups (anastomosis groups, AG) distinguished by lack of anastomosis between hyphae of strains. Phylogenetic analysis of internal transcribed spacer (ITS) sequences shows a strong correlation with AG determination. In this study, ITS sequences were reannotated according to the flanking 5.8S and 28S regions which interact during ribogenesis. One or two CBCs were detected between the ITS2 secondary structure of AG-3 potato strains as compared to AG-3 tobacco strains, and between these two strains and all other AGs. When a binucleate Rhizoctonia species related to Ceratobasidiaceae was compared to the AGs of R. solani, which were multinucleate (3-21 nuclei per cell), 1-3 CBCs were detected. The CBCs in potato strains of AG-3 distinguish them from AG-3 tobacco strains and other AGs yielding further evidence that the potato strains of AG-3 originally described as R. solani are a species distinct from other AGs. The ITS1-5.8S-ITS2 sequences were analyzed by direct sequencing of PCR products from 497 strains of AG-3 isolated from potato. The same 10 and 4 positions in ITS1 and ITS2, respectively, contained variability in 425 strains (86%). Nine different unambiguous ITS sequences (haplotypes) could be detected in a single strain by sequencing cloned PCR products indicating that concerted evolution had not homogenized the rRNA cistrons in many AG-3 strains. Importantly, the sequence variability did not affect the secondary structure of ITS2 and CBCs in AG-3.

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Characterization of Mycorrhizal Isolates of Rhizoctonia solani from an Orchid, Including AG-12, a New Anastomosis Group

Cited by 115 publications

References 22 publications

Review. Biology and systematics of the form genus Rhizoctonia

Review. Biology and systematics of the form genus Rhizoctonia

Virulence and molecular characterization of Costa Rican isolates of Rhizoctonia solani from common bean

Evolutionary Diversification Indicated by Compensatory Base Changes in ITS2 Secondary Structures in a Complex Fungal Species, Rhizoctonia solani

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