@article{copes_rodriguez-carres_toda_rinehart_cubeta_2011, title={Seasonal Prevalence of Species of Binucleate Rhizoctonia Fungi in Growing Medium, Leaf Litter, and Stems of Container-Grown Azalea}, volume={95}, ISSN={["0191-2917"]}, DOI={10.1094/pdis-11-10-0796}, abstractNote={ Rhizoctonia web blight is an annual problem on container-grown azalea (Rhododendron spp.) in the southern and eastern United States but little is documented about the distribution or persistence of Rhizoctonia spp. in container-grown azalea. Sixty web-blight-damaged azalea plants (‘Gumpo White’) were collected in August 2005 and 2006 and arranged in a completely randomized design on an outdoor irrigation pad. A nylon mesh bag containing 30 necrotic leaves collected from web-blight-damaged ‘Gumpo White’ azalea plants were placed on the surface of the medium under the plant canopy in each container to simulate leaf litter. Ten plants were destructively sampled into eight zones by dividing stems into three zones (lengths of 0 to 2, 4 to 6, and 9 to 15 cm above the medium surface), bagged leaves into one leaf litter zone, and the medium into four zones (three horizontal layers: 1 to 3, 3 to 7, and 7 to 10 cm below the medium surface, with the middle layer further divided by removing the central 7.5-cm-diameter core) in December, February, and May. Only the three stem zones were sampled from 10 plants in early and late June and late July. Of 8,940 total isolations, 3,655 fungi with morphological characteristics of a Rhizoctonia sp. were recovered. Percent recovery differed from the eight zones (P < 0.0001) but did not differ between years (P = 0.3950) and sampling times (P = 0.1896). Frequency of recovery of Rhizoctonia spp. was highest from the lower stem and the leaf litter, and decreased with distance from the leaf litter. Recovery from stems over the six sample times was analyzed separately. Percent recovery differed between stem zones (P < 0.0001), sample times (P = 0.0478), and experiment years (P < 0.0001). In both years, mean recovery of Rhizoctonia spp. was higher from the lower stem and decreased with distance to the upper stem layer. From a subsample of 145 isolates, 95.1% were identified as binucleate Rhizoctonia (BNR) anastomosis groups (AGs)-A, -G, -K, -R, -S, and -U (-P), and 2.8 and 2.1% were Rhizoctonia solani AG-2 and an uncultured Laetisaria sp., respectively. Based on frequency analysis, recovery of BNR AGs differed by plant zone (P < 0.0001) but not over sample times (P = 0.4831). The six AGs of BNR are the predominant Rhizoctonia fungi occupying the habitat niches in container-grown azalea, with little change in population frequency and composition from fall to summer; thus, BNR pathogenic and nonpathogenic to azalea have established a mixed Rhizoctonia community on container-grown azalea. }, number={6}, journal={PLANT DISEASE}, author={Copes, Warren E. and Rodriguez-Carres, Marianela and Toda, Takeshi and Rinehart, Tim A. and Cubeta, Marc A.}, year={2011}, month={Jun}, pages={705–711} }
 @article{qu_yamashita_toda_priyatmojo_kubota_hyakumachi_2008, title={Heterokaryon formation in Thanatephorus cucumeris (Rhizoictonia solani) AG-1 IC}, volume={112}, ISSN={["0953-7562"]}, DOI={10.1016/j.mycres.2008.02.009}, abstractNote={Approximately 50 single-basidiospore isolates (SBIs) obtained from each of 16 field isolates of Thanatephorus cucumeris AG-1 IC were examined for heterokaryon formation. All SBIs obtained from each field isolate were divided into two mating groups (SBIs-M1 and SBIs-M2), and tufts of mycelia were formed in the contact zone between colonies of paired SBIs-M1 and -M2 based on 0.5 % charcoal agar medium. Tufts were produced from all possible pairing between SBIs from non-parental field isolates. Hyphal anastomosis reactions indicated no cell death and random cell death at the contact cell, and was not related to tuft formation. AFLP phenotypes of SBIs from each field isolate were not identical to each other and were different from their parental field isolate. AFLP phenotypes of the tuft isolates formed from SBIs-M1 and SBIs-M2 from each field isolate were heterokaryotic. Moreover, several SBIs also formed tufts with their parental and non-parental field isolates. AFLP phenotypes of these tuft isolates suggested that they were all heterokaryotic. Results of these experiments suggest that T. cucumeris AG-1 IC is heterothallic and bipolar, and that genetic exchange can occur between homokaryotic and heterokaryotic isolates (Buller phenomenon).}, journal={MYCOLOGICAL RESEARCH}, author={Qu, Ping and Yamashita, Koji and Toda, Takeshi and Priyatmojo, Achmadi and Kubota, Mayumi and Hyakumachi, Mitsuro}, year={2008}, month={Sep}, pages={1088–1100} }
 @article{qu_aratani_syoji_toda_kubota_hyakumachi_2008, title={Use of single-protoplast isolates in the study of the mating phenomena of Rhizoctonia solani (Thanatephorus cucumeris) AG-1 IC and IA}, volume={49}, ISSN={["1340-3540"]}, DOI={10.1007/s10267-007-0400-6}, abstractNote={This study evaluates the effectiveness of using single-protoplast isolates (SPIs) to study the mating phenomena of Rhizoctonia solani AG-1 IC and IA. SPIs obtained from three field isolates (F-1, Rh28, and RO2) of AG-1 IC were paired with representative single-basidiospore isolate (SBI)-M1/-M2 testers, each from their own field isolates, or paired in all possible combinations. Tufts were formed between SPIs and SBI-M1/-M2 testers and between SPIs-M1 and -M2. The separation ratios of SPIs-M1 and -M2 were approximately 1 : 1, which were similar to the results obtained with SBIs. SPIs obtained from three isolates (GNSD, R59, and Tr8) of AG-1 IA, which failed to form basidiospores, were paired in all possible combinations. Although no tufts formed among SPIs from Tr8 and R59, tufts did form between SPIs from GNSD. SPIs from GNSD were separated into homokaryotic (-M1 or -M2) and heterokaryotic isolates, and the separation ratio of -M1 and -M2 was also around 1 : 1. Amplified fragment length polymorphism (AFLP) phenotypes of the tuft isolates formed between GNSD SPIs-M1 and -M2 suggested that these tuft isolates were all heterokaryotic. These results indicate that all three isolates of AG-1 IC and one isolate GNSD of AG-1 IA are heterokaryotic, and that the other two isolates of Tr8 and R59 of AG-1 IA are homokaryotic. Single-protoplast isolates are effective for studies of the mating phenomena of isolates belonging to different AGs of R. solani that could not form a perfect stage.}, number={2}, journal={MYCOSCIENCE}, author={Qu, Ping and Aratani, Akiko and Syoji, Takako and Toda, Takeshi and Kubota, Mayumi and Hyakumachi, Mitsuro}, year={2008}, month={Apr}, pages={132–137} }
 @article{rinehart_copes_toda_cubeta_2007, title={Genetic characterization of binucleate Rhizoctonia species causing web blight on azalea in Mississippi and Alabama}, volume={91}, ISSN={["1943-7692"]}, DOI={10.1094/PDIS-91-5-0616}, abstractNote={ Web blight on containerized azalea is an annual problem for commercial nurseries during summer months in the southern United States. Losses to web blight are associated with the cost of fungicide applications, delayed marketing of diseased plants, and plant death. Two hundred and eleven isolates of binucleate Rhizoctonia were recovered from azalea leaves with web blight symptoms from two nurseries in Mississippi and Alabama over 3 years. The internal transcribed spacer region (ITS) of the ribosomal DNA (rDNA) was sequenced from all isolates to determine genetic identity. A single anastomosis group (AG) of binucleate Rhizoctonia represented 92% of the samples collected from infected leaves. Genetic data and hyphal fusion experiments confirmed that these isolates belong to AG-U, which was recently identified from root and stem infections on miniature rose in Japan. Isolates of binucleate Rhizoctonia belonging to anastomosis groups AG-R, CAG-7 (=AG-S), and AG-G were also identified in the sample in low frequency. This is the first report of the occurrence of binucleate Rhizoctonia AG-U in the United States. }, number={5}, journal={PLANT DISEASE}, author={Rinehart, T. A. and Copes, W. E. and Toda, T. and Cubeta, M. A.}, year={2007}, month={May}, pages={616–623} }
 @article{hayakawa_toda_ping_mghalu_yaguchi_hyakumachi_2006, title={A new subgroup of Rhizoctonia AG-D, AG-D III, obtained from Japanese zoysia grass exhibiting symptoms of a new disease}, volume={90}, ISSN={["0191-2917"]}, DOI={10.1094/PD-90-1389}, abstractNote={ Isolates of an unidentified Rhizoctonia sp. (UN isolates) were obtained from Japanese zoysia grass (Zoysia japonica Steud) that exhibited symptoms of a new sheath rot disease. UN isolates were binucleate and showed hyphal fusion with tester isolates of Rhizoctonia anastomosis group (AG)-D. Those isolates were compared with isolates of subgroups I and II of Rhizoctonia AG-D based on cultural morphology, hyphal growth rate at different temperatures, anastomosis frequency, pathogenicity, and sequence analysis of the internal transcribed spacer (ITS) region of ribosomal DNA genes (rDNA-ITS region). The mycelial color of UN isolates was light yellow which differs from AG-D I but is similar to AG-D II. Sclerotia of UN isolates were dark brown in color and larger in size (1 to 3 mm in diameter) than those of AG-D subgroup I (1 mm in diameter), whereas isolates of AG-D II produced white mycelial clamps 4 to 5 mm in size. Hyphal growth rate of UN isolates was slower than that of two AG-D subgroups at several temperatures, especially 25°C. In pathogenicity tests on Japanese zoysia grass, UN isolates showed moderate disease severity and lower pathogenicity than isolates of AG-D subgroups I and II. Sequences of the rDNA-ITS region within UN isolates were almost homologous, but had lower homology with subgroups AG-D I or II. Phylogenetic trees constructed using ITS sequences showed that UN isolates formed an individual cluster that differed from the clusters of the two subgroups. We propose that UN isolates are a new subgroup of Rhizoctonia AG-D, subgroup III, and the name of the disease is “spring-rot” on Japanese zoysia grass. }, number={11}, journal={PLANT DISEASE}, author={Hayakawa, Toshihiro and Toda, Takeshi and Ping, Qu and Mghalu, Joseph M. and Yaguchi, Shigeharu and Hyakumachi, Mitsuro}, year={2006}, month={Nov}, pages={1389–1394} }
 @article{toda_hyakumachi_2006, title={Heterokaryon formation in Thanatephorus cucumeris anastomosis group 2-2 IV}, volume={98}, ISSN={["0027-5514"]}, DOI={10.3852/mycologia.98.5.726}, abstractNote={Thirty single basidiospore isolates (SBIs) obtained from four field isolates of the basidiomycete fungus Thanatephorus cucumeris AG 2-2 IV were examined for heterokaryon formation. SBIs of three of four field isolates (Rh509, 92155 and R94) did not produce a tuft of mycelium in the hyphal interaction zone between paired isolates on 2% charcoal agar. Field isolates Rh509, 92155 and R94 indicated no death of interacting mycelium with their progenies on glass slide and microscopic examination. AFLP (amplified fragment length polymorphism) phenotypes of parent and their SBIs were identical. Field isolates Rh509, 92155 and R94 and their SBIs were homothallic. SBIs obtained from field isolate SA-1 were grouped into two mating types (SBI-M1 and SBI-M2), and a tuft of mycelium was formed between paired SBIs-M1 and -M2. SBIs of field isolate SA-1 indicated that no death and death of interacting mycelium were randomly observed. AFLP phenotypes among SBIs of isolate SA-1 were not identical and were also different from their parent isolate. AFLP phenotypes of tuft mycelia produced between heterothallic SBI-M1 and -M2 were heterokaryotic. The mating system of field isolate SA-1 and its SBIs was heterothallic. Both SBIs-M1 and -M2 further produced tuft mycelium with homothallic field isolates and their SBIs. AFLP banding patterns suggested that tuft mycelium was heterokaryotic produced from between heterothallic and homothallic isolates. Results from these experiments clarified that both homothallic and heterothallic isolates exist in population of T. cucumeris AG 2-2 IV, and that genetic exchange can occur between homothallic and heterothallic isolates.}, number={5}, journal={MYCOLOGIA}, author={Toda, Takeshi and Hyakumachi, Mitsuro}, year={2006}, pages={726–736} }