The advancing identification and classification of Rhizoctonia spp. using molecular and biotechnological methods compared with the classical anastomosis grouping

Abstract

Anamorphic classification of Rhizoctonia spp. has been based on young cell nuclear numbers and hyphal fusion to anastomosis groups (AGs), in addition to the teleomorph classification. The widespread development of molecular biology techniques has added modern tools to support classification of organisms according to their genetics and evolutionary processes. These various methods have also been used in recent years for classification of Rhizoctonia. Data are continuously accumulating in the literature and the sequences in databases, which are readily available for researchers in the network systems. In the present review, attempts were made to describe and compare the advantages and disadvantages of the various methods for the classification of Rhizoctonia spp. Currently, the rDNAinternal transcribed spacer (ITS) sequence analysis seems to be the most appropriate method for classification of Rhizoctonia spp. Data of all the appropriate multinucleate Rhizoctonia (MNR) accumulated in GenBank were analyzed together in neighbor-joining (NJ) and maximumparsimony (MP) trees supplemented with percent sequence similarity within and among AGs and subgroups. Generally, the clusters of the isolate sequences were supportive of the AGs and subgroups based on hyphal fusion anastomosis. The review also indicates inaccuracies in designation of sequences of some isolates deposited in GenBank. The review includes detailed analyses of the MNR groups and subgroups, whereas complementary descriptions of the binucleate Rhizoctonia (BNR), uninucleate Rhizoctonia (UNR), and comprehensive interrelationships among all the currently available MNR, BNR, and UNR groups and subgroups in GenBank are to be discussed in a subsequent review article.

Further advances in orchid mycorrhizal research

“…that form ECM and associate with MH orchids (subgroup A) are distinct from essentially saprotrophic species and associates of photosynthetic orchids including the probable species complex Sebacina vermifera (subgroup B). Recent phylogenetic analyses have cast light on two other important orchid mycorrhizal fungal genera, Ceratobasidium and Thanatephorus (Binder et al 2005;Sharon et al 2006;Gonzalez et al 2006) but more sequences need to be examined to complete the picture. The common orchid associating genus Tulasnella contains many undescribed species and some phylogenetically problematic taxa eg.…”

Assessing genetic diversity in the web blight pathogen Thanatephorus cucumeris (anamorph = Rhizoctonia solani) subgroups AG-1-IE and AG-1-IF with molecular markers

“…A comprehensive review of molecular methods used for characterization and classification of Rhizoctonia spp. has been published by Sharon et al (2006). Other dominant molecular markers that have been used in recent fingerprinting studies for R. solani are universal rice primers (URP) (Kang et al 2002) and inter simple sequence repeats (ISSR) (Gupta et al 1994).…”

AFLP Fingerprinting for Identification of Infra-Species Groups of Rhizoctonia solani and Waitea circinata

“…W. circinata group consisted of varieties zeae, circinata and an unidentified subgroup. other DNA fingerprinting techniques are more efficacious for studying genetic variation of Rhizoctonia at the individual level rather than at the subgroup level within an AG or different AGs [6,37]. However, these hypotheses were based on few studies without proper investigation of analyzing a large number of Rhizoctonia and Waitea isolates belonging to different AGs.…”

“…cerealis Van der Hoeven, AG-D) have been reported from diseased turf lawns and golf greens [1][2][3][4]. Rhizoctonia solani is a genetically diverse species consisting of many Anastomosis Groups (AGs) [5,6]. Six AGs have been reported to cause blight in turfgrass with AG 1(-IA and -IB), AG 2 (-2IIIB and -2LP), and AG 4 being more common on infected turfgrasses than other AGs [7,8].…”