scholarly journals Rhizoctonia cerealis anastomosis group GAG-1, the common pathogen of wheat, barley and sugar beet

2014 ◽  
Vol 32 (1) ◽  
pp. 107-117
Author(s):  
Helena Furgał-Węgrzycka ◽  
Jan Adamiak ◽  
Ewa Adamiak
Keyword(s):  
Growth Rate ◽  
Sugar Beet ◽  
Crop Rotation ◽  
Root Rot ◽  
Anastomosis Group ◽  
Sharp Eyespot ◽  
Pathogenicity Tests ◽  
The Common ◽  
Hyphal Diameter ◽  
Rhizoctonia Cerealis

Isuluies of <i>Rhizoctonia cerealis</i> anastomosis group GAG-1 were obtained from sharp eyespot lesions on wheat and on barley culms and from diseased sugar beet seedlings. Isolates of <i>R. cerealis</i> were collected from a fields with crop rotation experiments: sugar beet-spring wheat-winter barley. In pathogenicity tests isolates of <i>R. cerealis</i> from sugar beet seedlings and from sharp eyespot lesions on wheat and barley were pathogenic to these crops. Isolates of <i>R. cerealis</i> from sharp eyespot lesions on wheat and barley caused severe damping-ofTof sugar beet. Isolates of <i>R. cerealis</i> from sugar beet seedlings also caused symptoms of sharp eyespot on wheat and barley. None of the wheat and barley isolates of <i>R. cerealis</i> tested caused root-rot on wheat or barley seedlings. Isolates of <i>R. cerealis</i> obtained from diseased plants of wheat, barley and sugar beet were similar in morphology of cultures and anastomosed with GAG-1 tester isolate. The relatinoship between anastomosis. colony characters, growth rate, hyphal diameter and pathogenicity of AG-4. AG-2-2 and AG-5 isolates obtained together with <i>R. cerealis</i> from diseased plants were also investigated.

scholarly journals Some characteristic of Rhizoctonia spp. in sharp eyespot of wheat

2014 ◽  
Vol 31 (2) ◽  
pp. 199-208 ◽  
Author(s):  
Helena Furgał-Węgrzycka ◽  
Jan Adamiak ◽  
Ewa Adamiak
Keyword(s):  
Growth Rate ◽  
Root Rot ◽  
Colony Growth ◽  
Anastomosis Group ◽  
Wheat Seedlings ◽  
Binucleate Cells ◽  
Ne Poland ◽  
Sharp Eyespot ◽  
Hyphal Anastomosis ◽  
H 20

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.

scholarly journals Characterization and fungicides sensitivity of Phytophthora cinnamomi isolates causing avocado root rot in Zitácuaro, Michoacán

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Alejandra Mondragón-Flores ◽  
Patricia Manosalva ◽  
Salvador Ochoa-Ascencio ◽  
Marlene Díaz-Celaya ◽  
Gerardo Rodríguez-Alvarado ◽  
...  
Keyword(s):  
Growth Rate ◽  
Mating Type ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Potassium Phosphite ◽  
Pathogenicity Tests

<em>Phytophthora cinnamomi</em> is the pathogen most frequently associated with avocado root rot. In Zitácuaro, Michoacán, production has increased by 19.8%; however, there are no studies of root rot in this area. The objective of the study was to characterize the isolates obtained from avocado roots and assess the sensitivity to fungicides. Samples from 5 avocado orchards were collected, sampling 5 trees per orchard (a total of 25 samples). The samples isolated were characterized morphological and molecularly. Mating type was analyzed using reference isolates of<em> P. cinnamomi</em> A1 (isolate from camelia) and A2 (isolate from avocado). To confirm the pathogenicity, tests were performed on avocado fruits with the isolates. The sensitivity of 15 isolates to potassium phosphite and to metalaxyl-M at different concentrations was evaluated<em> in vitro</em>. In a subgroup of six isolates, it was evaluated whether there was a relationship between growth rate and potassium phosphite sensitivity. Fifteen isolates were obtained with coenocytic coraloid mycelium, chlamydospores, sporangia without papilla, ovoid to ellipsoid, with internal proliferation, heterothallic with mating type A2, with amphigynous antheridia and plerotic oospores, characteristics consistent with <em>P. cinnamomi</em>. The inoculated isolates were pathogenic on avocado fruits. The isolates were more sensitive to potassium phosphite than to metalaxyl-M, with mean EC50 values of 24.62 and 0.215 ?g mL-1 of i.a., respectively. No relationship was observed between growth rate and potassium phosphite sensitivity. It is necessary to obtain a greater number of<em> P. cinnamomi</em> isolates for virulence studies.

Relationship of binucleate Rhizoctonia isolates used for biocontrol of rhizoctonia crown rot of sugar beet to anastomosis systems

1991 ◽  
Vol 37 (5) ◽  
pp. 339-344 ◽  
Author(s):  
Leonard J. Herr
Keyword(s):  
Sugar Beet ◽  
Root Rot ◽  
Anastomosis Group ◽  
The Other ◽  
Crown Rot ◽  
Considerable Heterogeneity ◽  
Binucleate Rhizoctonia ◽  
Crown And Root Rot ◽  
Relationship Of ◽  
Intraspecific Group

The relationships of 10 binucleate Rhizoctonia isolates used as biocontrol agents of rhizoctonia crown and root rot of sugar beet in Ohio to described binucleate Rhizoctonia anastomosis systems were investigated. Ten Ohio binucleate Rhizoctonia (Ohio BNR) isolates, paired in all combinations, cross anastomosed with one another, indicating that all belong to the same anastomosis group. Four representative Ohio BNR isolates failed to anastomose with any tester isolates of the Ceratobasidium anastomosis grouping system, indicating that none belong in that system. However, all 10 Ohio BNR isolates anastomosed with an AG-B (o) tester isolate (binucleate Rhizoctonia anastomosis grouping system), indicating that the Ohio agents belong in this anastomosis grouping system and to the (o) intraspecific group of AG-B. None of the Ohio BNR isolates anastomosed with either of the other two intraspecific group tester isolates (AG-Ba, AG-Bb) of the AG-B group. Moreover, the AG-B intraspecific group tester isolates, AG-Ba, AG-Bb, AG-B (o), self-anastomosed but did not cross anastomose with one another. Variations in cultural characteristics noted among the 10 Ohio BNR isolates indicated that considerable heterogeneity exists within these AG-B (o) isolates. Key words: binucleate Rhizoctonia, anastomosis, rhizoctonia crown rot, sugar beet.

scholarly journals Influence of selected Rhizoctonia solani isolates on sugar beet seedlings

2016 ◽  
Vol 56 (2) ◽  
pp. 116-121
Author(s):  
Paweł Skonieczek ◽  
Mirosław Nowakowski ◽  
Jacek Piszczek ◽  
Marcin Żurek ◽  
Łukasz Matyka
Keyword(s):  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Root Rot ◽  
Laboratory Tests ◽  
Anastomosis Group ◽  
Damping Off ◽  
Highly Pathogenic ◽  
Breeding Lines ◽  
Brown Root Rot

Abstract From 2008 to 2010 the levels of sugar beet seedlings infection caused by Rhizoctonia solani were compared in laboratory tests. Seven sugar beet lines were tested: H56, H66, S2, S3, S4, S5 and S6 as well as three control cultivars: Carlos, Esperanza and Janosik. Sugar beet lines with tolerance to rhizoctoniosis and cultivars without tolerance were infected artificially by R. solani isolates: R1, R28a and R28b. These isolates belong to the second anastomosis group (AG), which is usually highly pathogenic to beet roots. The aim of the experiment was to test whether the tolerance of sugar beet genotypes to R. solani AG 2 prevents both root rot, and damping-off of seedlings, induced by the pathogen. Sugar beet lines tolerant to brown root rot in laboratory tests were significantly less sensitive to infection of the seedlings by R. solani AG 2 isolates in comparison to control cultivars. Rhizoctonia solani AG 2 isolates demonstrated considerable differences in pathogenicity against seedlings of sugar beet lines and cultivars. The strongest infection of sugar beet seedlings occurred with the isolate R28b. The greatest tolerance to infection by AG 2 isolates was found for the S5 and S3 breeding lines.

scholarly journals Genetic Structure of Populations of the Wheat Sharp Eyespot Pathogen Rhizoctonia cerealis Anastomosis Group D Subgroup I in China

2017 ◽  
Vol 107 (2) ◽  
pp. 224-230 ◽  
Author(s):  
Wei Li ◽  
Yingpeng Guo ◽  
Aixiang Zhang ◽  
Huaigu Chen
Keyword(s):  
Genetic Structure ◽  
Anastomosis Group ◽  
Gene Pools ◽  
Evolutionary Potential ◽  
Long Distance ◽  
Genetic Characteristics ◽  
Nonrandom Mating ◽  
Sharp Eyespot ◽  
Group D ◽  
Rhizoctonia Cerealis

Sharp eyespot on wheat is caused by Rhizoctonia cerealis anastomosis group D subgroup I (AG-DI) and is an economically important stem-base disease of wheat in temperate regions worldwide. However, the understanding about the field population structure of R. cerealis is limited. In this study, the genetic structure of four wheat-infecting populations in China was investigated using six microsatellite markers characterized from the transcriptome data of R. cerealis AG-DI. A total of 173 unique genotypes were identified among 235 fungal isolates. Departure from Hardy-Weinberg equilibrium, a significant degree of inbreeding, and a significant deficit in heterozygotes indicated a nonrandom mating pattern. Combining the low to intermediate degrees of gametic disequilibrium, although with high genotypic diversity and low to moderate clonal fractions, sexual reproduction probably existed, but the asexual reproduction should be the predominant reproductive mode. Structural analysis showed three gene pools among the four populations, which indicated the existence of three evolutionary origins of R. cerealis AG-DI. The long-distance movement of contaminated material, especially the infected seed, might have caused the moderate gene flow among these populations, which was consistent with the high differentiation among these populations. Overall, the genetic characteristics of the populations suggested a moderate evolutionary potential for R. cerealis AG-DI in China.

scholarly journals Identification of Rhizoctonia solani isolates from sugar beet roots by analyzing the ITS region of ribosomal DNA

2007 ◽  
pp. 161-171 ◽  
Author(s):  
Vera Stojsin ◽  
Dragana Budakov ◽  
Barry Jacobsen ◽  
Eva Grimme ◽  
Ferenc Bagi ◽  
...  
Keyword(s):  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Ribosomal Dna ◽  
Root Rot ◽  
Its Region ◽  
Anastomosis Group ◽  
Crown Rot ◽  
Internal Transcribed Spacer Region ◽  
The Usa ◽  
Crown And Root Rot

Rhizoctonia solani (K?hn) is one of the most important sugar beet pathogens Rhizoctonia solani anastomosis groups (AGs) 2-2 and 4 are proven to be the most common pathogenic strains on sugar beet. AG 2-2 (intraspecific groups IIIB and IV) can cause root and crown rot while damping-off of seedlings is most frequently attributed to AG 4. Four isolates of R. solani from sugar beet roots showing characteristic crown and root rot symptoms, collected from different localities in Vojvodina Province, were chosen and compared to the well-characterized R. solani isolate R9, AG 2-2 IV, from the USA. All Vojvodinian isolates showed medium level of pathogenicity and were able to cause crown and root rot symptoms on inoculated sugar beet roots. Based on anastomosis reaction, isolates from Vojvodina did not belong to the AG 2-2 group. Sequencing of the ITS (internal transcribed spacer) region of ribosomal DNA was performed on the Vojvodinian isolates from R9 in order to determine their relatedness. Sequence analysis showed that these isolates were different than R9 and were closely related (99-100% sequence homology) to anastomosis group 4, subgroup HG II.

Effect of Low Temperature on the Aggressiveness of Rhizoctonia solani AG 2-2 Isolates on Sugar Beet (Beta vulgaris) Seedlings

Plant Disease ◽  
2021 ◽  
Author(s):  
Douglas H. Minier ◽  
Linda E. Hanson
Keyword(s):  
Growth Rate ◽  
Low Temperature ◽  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Anastomosis Group ◽  
Damping Off ◽  
Sugar Beets ◽  
Disease Symptoms ◽  
Severity Scores ◽  
Soil Temperatures

Rhizoctonia solani anastomosis group (AG) 2-2 can cause seedling damping-off in sugar beets and substantial losses may occur in all regions where beets are grown. Sugar beets are planted early in the season when soil temperatures are low in order to maximize the length of the growing season and minimize the risk of damping-off. However, predictive models that indicate there is little to no risk of Rhizoctonia damping-off at temperatures <15°C may not be entirely reliable. We tested this possibility by inoculating sugar beet seedlings in a growth chamber at 11°C with 35 R. solani AG 2-2 isolates that were representative of the genetic diversity present in AG 2-2. Although disease progress and growth rate were greatly reduced at 11°C, considerable disease symptoms did develop in inoculated plants. Three weeks after inoculation, 16% of the plants were dead and 77% of the isolates tested had average disease severity scores that were significantly greater than those of the mock inoculated control. This confirms our concern about the possibility for low-temperature infection of sugar beets and indicates that waiting until the soil warms up to above 15°C to apply fungicide could leave the crop at risk. Aggressiveness does not appear to be related to subgroup or growth rate but rather depends on the response of the specific isolate to low temperature.

scholarly journals Selection for Resistance to the Rhizoctonia-Bacterial Root Rot Complex in Sugar Beet

Plant Disease ◽  
2013 ◽  
Vol 97 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Carl A. Strausbaugh ◽  
Imad A. Eujayl ◽  
Paul Foote
Keyword(s):  
Sugar Beet ◽  
Root Rot ◽  
Field Studies ◽  
Anastomosis Group ◽  
Cultivar Differences ◽  
Commercial Sugar ◽  
Selection For ◽  
Group 2 ◽  
Bacterial Rot ◽  
Production Areas

The Rhizoctonia-bacterial root rot complex continues to be a concerning problem in sugar beet production areas. To investigate resistance to this complex in 26 commercial sugar beet cultivars, field studies and greenhouse studies with mature roots from the field were conducted with Rhizoctonia solani anastomosis group 2-2 IIIB strains and Leuconostoc mesenteroides. Based on means for the 26 cultivars in the 2010 and 2011 field studies, fungal rot ranged from 0 to 8%, bacterial rot ranged from 0 to 37%, total internal rot ranged from 0 to 44%, and surface rot ranged from 0 to 52%. All four rot variables resulted in significant (P < 0.0001) cultivar differences. Based on regression analysis, strong positive relationships (r2 from 0.6628 to 0.9320; P < 0.0001) were present among the rot variables. When ranking cultivars, the most consistent rot variable was surface rot, because 12 of 13 variable–year combinations had significant (P ≤ 0.05) correlations. When cultivar ranking in greenhouse assays was compared, there was frequently a positive correlation with storage data but no relationship with field results. Thus, the greenhouse assays will identify storage rot resistance but field screening will be required to find resistance to this rot complex in the field.

Exploration of Endophytes from Alfalfa (Medicago sativa L.) as Biocontrol Agents

2020 ◽  
pp. 1-8
Author(s):  
Beilei Wu ◽  
Beilei Wu ◽  
Mei Li ◽  
Xiaoli Chen ◽  
Xiliang Jiang ◽  
...  
Keyword(s):  
Medicago Sativa ◽  
Root Rot ◽  
Agricultural Production ◽  
Biocontrol Agents ◽  
Bacillus Spp ◽  
Medicago Sativa L ◽  
The Common ◽  
Seedling Germination ◽  
Germination Experiments ◽  
Alfalfa Root

Endophytes are increasingly investigated as biocontrol agents for agricultural production. The identification of new endophytes with high effectiveness against plant disease is very important. A total of 362 strains of endophytes, including fungi, bacteria, and actinomycete, were isolated from alfalfa (Medicago sativa L.) collected in Hebei, Inner Mongolia and Ningxia provinces of China. The three strains of endophytic bacteria (NA NX51R-5, NA NX90R-8, and NA NM1S-1) with strong biocontrol capability with >50% effectiveness were screened against the common alfalfa root rot pathogen Fusarium oxysporum F. sp. medicaginis in alfalfa seedling germination experiments on MS medium and pot experiments. Using phylogenetic analysis, the isolates of NA NM1S-1 and NA NX51R-5 were identified as Bacillus spp. by 16S rDNA, while NA NX90R-8 was found to be Pseudomonas sp.

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