Characterization of a new cultural type (LP) of Rhizoctonia solani AG2‐2 isolated from warm‐season turfgrasses, and its genetic differentiation from other cultural types

Abstract

Isolates of Rhizoctonia solani AG2-2 obtained from turf with symptoms of large-patch disease of warm-season turfgrasses were compared with known AG2-2 isolates belonging to cultural types IIIB and IV. Some isolates that were previously identified as type IV have been separated here and named LP isolates. Comparisons among isolates were based on cultural morphology, hyphal growth rate, pathogenicity and restriction fragment length polymorphism (RFLP) analysis in the nuclear encoded ribosomal DNA (rDNA) genes. The cultural characteristics of LP isolates varied from those of types IIIB and IV. LP isolates did not show distinct sclerotial formation and zonation, and the colour of their mycelia and pigment deposition was dark brown. LP isolates had slower hyphal growth rates than types IIIB and IV, with an optimum temperature of 25ЊC compared with 28ЊC for types IIIB and IV. LP isolates were less virulent on radish but highly virulent on zoysia grass when compared with isolates of types IIIB and IV. Genomic DNA was digested separately with Eco RI, Ban III, Xba I and Sal I, and probed with cloned rDNA from Alternaria alternata in Southern hybridizations. LP isolates had one RFLP pattern, while both IIIB and IV possessed four different patterns each. Cluster analysis of RFLPs showed that R. solani AG2-2 is divided into three genetic subgroups, consisting of the IIIB, IV and LP isolates, respectively. The polymerase chain reaction (PCR) amplified rDNA internally transcribed spacer (ITS) regions of the IIIB, IV and LP isolates had the same length but produced different restriction patterns when digested with Msp I and Taq I. These results indicate that there are three cultural types in R. solani AG2-2, namely IIIB, IV and LP.

Caracterização de isolados de Rhizoctonia spp. e identificação de novos grupos de anastomose em jardim clonal de eucalipto

“…A maior freqüência de isolados AG2-2 no solo pode ser resultado da maior capacidade saprofítica (Hashiba & Kobayashi, 1996). Os isolados AG2-2, identificados conforme os critérios de freqüência de anastomose de hifas e auxotrofia para tiamina (Ogoshi, 1996) e crescimento a 35 o C, foram incluídos no subgrupo AG2-2 IIIB (Hyakumachi et al, 1998). Dentre os isolados AG2-2 obtidos do solo, observaram-se diferentes tipos morfológicos, os quais foram distintos daqueles coletados de estacas em casa de vegetação, similares a AG2-2 IIIB.…”

A Comprehensive Overview on Black Scurf of Potato

“…At present, 13 AGs (designated AG-1 through AG-13) and 21 subgroups (designated AGs 1-IA, 1-IB, 1-IC, 1-ID, 2-1, 2-2-IIIB, 2-2-IV, 2-2-LD, 2-3, 2-4, 2-BI, 3-IIA, 3-IIB, 3-IIC, 3-TB, 4-HG-I, 4-HG-II, 6-GV, 6-HG-I, 9-TX, 9-TP) are recognised (Ogoshi, 1987;Naito and Kanematsu, 1994;Carling, 1996;Hyakumachi et al, 1998;Carling et al, 1999Carling et al, , 2002aKuninaga et al, 2000a;Priyatmojo et al, 2001). Subgroups within AGs are partially based on differences in one or more biochemical, genetic, or pathogenic characteristic (Ogoshi, 1987).…”

Development of specific PCR primers for the detection ofRhizoctonia solaniAG 2-2 LP from the leaf sheaths exhibiting large-patch symptom on zoysia grass

“…were maintained on corn meal agar at 25 ‡C. Total DNA of isolates was extracted as described by Hyakumachi et al [5].…”

“…were transferred on potato dextrose agar plates and incubated for 2 weeks at 25 ‡C. Isolates of R. solani AG 2-2 LP were determined by comparing the cultural morphology with descriptions by Hyakumachi et al [5]. The frequency of leaf sheaths infected with isolates of the LP type detected by isolation was compared to that detected by PCR.…”

“…PCR using primers A091-F/R on R. solani AG 1^10 and BI and turfgrass pathogens. Lane 1, LP isolate; lanes 2^16, AG1-IA, IB, IC, 2-tulip, 3,4,5,6,7,8,9,10 and BI isolates respectively; lanes 17^21, Rhizoctonia AG-D (I), AG-D (II), R. circinata var. oryzae, var.…”