Pathogenicity of Rhizoctonia cerealis to Wheat in Jiangsu Province
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Different methods for evaluating the pathogenicity of Rhizoctonia cerealis to wheat were tested with 7 isolates of the fungus.According to the results,a preferable method is to sow germinating wheat seeds in the PDA colony of the test isolated and incubated in growth chamber.The disease incidence was as high as 60 4% on average and the difference in disease severity between isolates was significant at the 5% probablility level. 30 isoates of Rhizoctonia cerealis were tested for their pathogenicity to wheat using this method.There were 4 pathogenicy types in these isolates.JR5,JR7,JR44 and other 7 isolates were classified as strong pathogenicity ;9 isolates such as JR127,JR13,JR52 and JR89 et al had less strong pathogenicity ;the pathogenicity of 6 isolates including JR117,JR2,JR47 and JR56 was weak. JR19 and JR22 had no pathogenicity to wheat.Keywords:
Rhizoctonia
Take-all
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Thirty two rice sheath blight pathogen strains(Rhizoctonia solani) were isolated from the infected rice samples from seven distinctive areas of Anhui Province,and their pathogenicity and genetic diversity were analyzed.Pathogenic differentiation analysis indicated that the pathogenicity among the strains was significantly different.The pathogenicity of the majority isolates was moderate in Anhui province.The genetic diversity of 32 Rhizoctonia solani strains was analyzed by RAPD.The results showed that the pathogenic and genetic diversity among the tested isolates were high,the polymorphic rate was 98.2%,and the genetic similarity coefficients of the isolates were 0.62-0.84.All the strains could be classified into 4 groups at the similarity coefficient of 0.653,and most of the isolates from the same area were consistent,but the pathogenicity showed no significant correlation within the RAPD groups.
Genetic similarity
Sheath blight
Rhizoctonia
Genetic Analysis
Fungal pathogen
Similarity (geometry)
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171 Rhizoctonia isolates were collected from different areas of Jiangsu province in 2001.The identification results showed,among these isolates 169 isolates were Rhizoctonia cerealis with percentage of 98.83%,2 isolates were Rhizoctonia solani.Among these R.cerealis isolates,158 isolates were in CAG1 anastomosis group,11 isolates were in other anastomosis group. The 2 isolates of R.solani were in AG2 anastomosis group based on blast of their ITS sequences.The pathogenicity of all isolates was evaluated with artificial inoculation method.The results showed that virulence of all these isolates was different significantly,the virulence of R.cerealis isolates was higher than that of R.solani isolates.No significant difference was observed among different anastomosis of R.cerealis.The virulence of isolates from 13 cities was significantly different.The virulence of isolates from Wuxi,Lianyungang,Taizhou was the highest,the virulence of isolates from Nantong were the lowest.
Rhizoctonia
Eyespot
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Rhizoctonia
Root rot
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Abstract Rhizoctonia solani isolates used in this investigation were identified as anastomosis-4 (AG-40), collected from different localities from Assiut governorate in Egypt. Pathogenicity test of seven isolates of R. solani was evaluated on soybean Giza 111 cultivar under greenhouse conditions. All tested isolates were able to infect soybean plants causing root rot with different degrees of severities, isolate No. 1, 2 and 3 showed significantly highest root rot severity, while isolate No. 5 gave the lowest percentage of root rot rating. The sodium dodecyl sulphate polyacrylamide gel electrophoresis patterns were used to compare three isolates of R. solani. There are no variations among R. solani isolates except a few exceptions according to their protein patterns. DNA markers obtained from all isolates showed genetic similarity among different isolates obtained from different geographical regions barring few exceptions. Correlation between DNA patterns of R. solani isolates and their virulence was detected, but no correlation with anastomosis groups (AG). Keywords: soybeanroot rotprotein patternsRAPD-PCR Rhizoctonia solani
Root rot
Rhizoctonia
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Fifty-eight isolates of Rhizoctonia spp.were isolated from thirteen plants in Guangdong Province.After determining their classification of Rhizoctonia spp.and anastomosis groups(AGs)of Rhizoctonia solani,these isolates were all tested on rice,sweet corn,cucumber and cabbage to determine their cross pathogenicity.The results showed that the isolates from corn and sweet corn,which were assigned to AG-1,had strong pathogenicity on the four tested plants;while isolates from other plants,which were assigned to AG-4,had middle pathogenicity on the four tested plants;and isolates from other crops,which belonged to AG-2 or maybe other AGs,had weak pathogenicity on the four tested plants.
Rhizoctonia
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Radiata
Pusa
Rhizoctonia
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Fifty-five Rhizoctonia solani samples were collected in rice from five distinctive ecological regions of Sichuan Province,China.The 55 representative samples were isolated and purified,and the pathogenicity and molecular genetic variation were analyzed.Hyphal fusion identification results revealed that all the 55 strains belonged to AG-1IA group except strain D42.In addition,some of the bacteria were identified to be fused with several groups simultaneously,acting as bridge flora.Pathogenicity identification analysis from leaves in vitro indicated that the pathogenicity among the strains was significantly different.The 55 strains could be classified into 8 groups by further RAPD cluster analysis when the similarity coefficient was 0.941.The results suggested that in the certain ecological conditions in Sichuan Province,most of the Rhizoctonia solani were genetically stable,but quite a few changed drastically.
Rhizoctonia
Genetic similarity
Strain (injury)
Genetic Analysis
Mycology
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The biological characteristics of 130 and 21 Rhizoctonia isolates collected from wheat and corn in different areas of Hebei province in 2005 were tested.The result showed that the Rhizoctonia growth on different medium was clearly different.The order of growth speed on different medium was PDA mediamaize mediawater agar media.The Rhizoctonia can grow well on PDA medium with pH 4-9,the optimum pH value was pH6.The O-KOH dyeing results indicated that 122 isolates out of 130 Rhizoctonia isolates from wheat were Rhizoctonia cerealis with percentage of 93.85%,8 isolates were Rhizoctonia solani with percentage of 6.15%;2 isolates and 19 isolates out of 21 Rhizoctonia isolates from corn were Rhizoctonia cerealis with percentage of 9.52% and Rhizoctonia solanis with percentage of 90.48%,respectively.The pathogenicity of some typical isolates was valuated by artificial cross-inoculation.The results showed that the virulence of different isolates were different,the virulence of Rhizoctonia on original host was higher than that on the other hosts.
Rhizoctonia
Eyespot
Corn meal
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Isolates of <i>Rhizttctonia</i> sp. with multinucleate and binucleate cells were obtained from sharp eyespot lesions on wheat culms in Olsztyn region. (NE Poland). These isolates were compared to isolates of AG-4 and GAG-1 testers with reference to cultural morphology of colony, growth rate, hyphal anastomosis and pathogenicity to wheat seedlings. The wheat binucleate isolates were similar in morphology of colonies and anastomosed with the <i>Ceratubasidium</i> anastomosis group GAG-1 tester isolates of <i>R. cerealis</i>. Growth rates on PDA ranged from 9 to 11 mm/24h for wheat isolates and from l to 11 mm/24 h for tester isolates GAG-1 of <i>R. cerealis</i>. The wheat multinucleate isolates were similar in morphology of colonies and anastomosed with <i>Rhizoctonia solani</i> Kühn group AG-4 tester isolate. <i>R. solani</i> AG-4 isolates were morphologically distinct from the <i>R. cerealis</i> isolates. These isolates on PDA were dark and grow rapidly (20-30 mm diam./24 h/20°C) and significantly contrasted with slowly growing white-creamy isolates of <i>R. cerealis</i> (GAG-1). Isolates of <i>R. solani</i> (AG-4) and <i>R. cerealis</i> (GAG-I) developed sharp eyespot lesions on culms and white head symptoms typical of the disease. None of the wheat isolates of <i>R. cerealis</i> (GAG-I) caused root-rot on wheat seedlings. In the present work the classification system of vegetative groups of <i>Rhizoctonia</i> spp. in present work is also discussed.
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Rhizoctonia
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Twenty-three isolates of Rhizoctonia spp. from agronomic crops and turfgrasses were characterized by cytological and pathological methods in order to establish the identity, pathogenicity, and virulence of Rhizoctonia spp. and anastomosis groups that occur on these hosts in Mississippi. Twelve isolates were identified as R. solani, including the five anastomosis groups (AGs) AG-1-IB, AG-2-2, AG-4, AG-5, and AG-13. Rhizoctonia zeae, R. oryzae, and eight binucleate Rhizoctonia sp., including R. cerealis, also were identified. R. solani AG-4 isolates were consistently the most virulent isolates on all hosts in pathogenicity evaluations. Pathogenicity of AG-2-2 and AG-5 isolates, binucleate Rhizoctonia spp., and R. oryzae varied between hosts. Two AG-2-2 isolates from bermudagrass or wheat were determined to be clonal isolates, with numerous self-anastomosis reactions. R. solani (AG-1-IB) was pathogenic on all graminaceous hosts. R. cerealis produced sharp eyespot symptoms on wheat and corn and minimal symptoms on cotton and soybean. This is a first report of R. cerealis as a pathogen of corn. R. zeae isolates were pathogenic on all hosts, including cotton and soybean. These results indicate that a diverse group of Rhizoctonia spp. occurs as pathogens on a wide variety of agronomic crops and turfgrasses in Mississippi.
Rhizoctonia
Stolon
Eyespot
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