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1.
ABSTRACT Isolates of Rhizoctonia solani collected from mycorrhizal orchid (Pterostylis acuminata) plants and adjacent leaf litter were characterized. Of 23 selected isolates, 20 were members of a new anastomosis group (AG-12) and the rest were members of AG-6. There were no bridging anastomosis reactions observed between AG-12 and other AGs of R. solani. Among the 20 isolates of AG-12 evaluated, 18 vegetatively compatible populations were detected, indicating diversity within the AG. Mature cultures were dark brown, as were mature sclerotia. Some cultures produced alternating dark- and light-colored concentric rings, with sclerotia forming in the darker rings. Most cultures were appressed to the agar surface. In tests run to characterize pathogenic potential, selected mycorrhizal isolates of AG-12 and AG-6 did little damage to potato and barley seedlings, moderate damage to head lettuce seedlings, and more extensive damage to seedlings of cauliflower and radish. Isolates of AG-12 have not been observed to fruit in nature, and all attempts to induce formation of the teleomorph (Thanatephorus cucumeris) in the laboratory by selected isolates of AG-12 failed. 相似文献
2.
从新疆11种豆科作物病株上或病株根围土样中分离纯化出250个立枯丝核菌（Rhizoctonia DC）,番红O KOH染色后观察细胞核数目,经测试全部菌株均为多核,用标准菌株测定融合群, 250个菌株分属为AG 1、AG 2、AG 3、AG 4和AG 5共5个融合群,出现频率分别为16.4%、33.2%、0.4%、32.4%和17.6%,营养亲合群判别结果表明,AG 1、AG 2、AG 4和AG 5下各有2个VCG,说明新疆豆科作物立枯丝核菌各主要菌丝融合群内均有不同程度的分化。 相似文献
3.
Tomoo Misawa Daisuke Kurose Manami Mori Takeshi Toda 《Journal of General Plant Pathology》2018,84(6):387-394
Rhizoctonia solani AG-2-1 is classified into three subsets (Subsets 1–3) based on the rDNA-ITS sequence. Few Japanese isolates, however, have been phylogenetically analyzed. To understand the distribution and diversification of AG-2-1 isolates in Japan, we examined 23 Japanese AG-2-1 isolates (15 from Hokkaido, the northernmost island, and eight from NARO Genebank) in terms of rDNA-ITS sequences, culture morphology, and temperature-dependent growth characteristics. Of these, 15 isolates were found to belong to Subset 1. One isolate, which formed a light brown colony with concentric rings and grew slowly at 25 °C, was classified into Subset 2. Six isolates had varied culture morphology and relatively faster growth than Subset 1 isolates at 30 °C. They formed a clade on the phylogenetic tree, designated clade HK, with cauliflower isolates from Belgium and the Netherlands, with a bootstrap value of 47%, and were separate from the three known subsets. Sequence similarity in the rDNA-ITS region for this clade ranged from 98.2 to 100%, whereas clade HK isolates had 96.7–98.6% similarity with the isolates in each subset. This result suggests that clade HK is likely an independent intragroup within AG-2-1, although the rDNA-ITS sequences in this clade were variable. One isolate was not assignable to any clade because it was intermediate between isolates in clade HK and Subset 2. This is the first report describing variation among rDNA-ITS sequences of Japanese AG-2-1 isolates. 相似文献
4.
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 25°C compared with 28°C 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. 相似文献
5.
Anastomosis group and pathogenicity of isolates of Rhizoctonia solani from potato crops in South Australia 总被引：1，自引：1，他引：1
G. R. BALALI S. M. NEATE E. S. SCOTT D. L. WHISSON T. J. WICKS 《Plant pathology》1995,44(6):1050-1057
Isolates of Rhizoctonia collected from the stems, roots, tuber sclerotia and soil of potato crops in Virginia and Lenswood, South Australia, were identified to anastomosis groups (AG). Of the 301 multinucleate isolates of Rhizoctonia solani tested, 90% were AG-3, 7% were AG-4 and 2% were AG-5; 12 isolates were binucleate Rhizoctonia spp. This is the first report of isolates of AG-4 and AG-5 causing disease in potato crops in South Australia. All AG-3, AG-4 and AG-5 isolates tested caused rhizoctonia disease symptoms on the potato cultivar Coliban in pathogenicity trials conducted under glasshotise conditions. Both AG-3 and AG-5 isolates caused black scurf and stem cankers, although symptoms of black scurf were less severe with AG-5. AG-4 isolates produced the most severe stem and stolon cankers of all isolates tested. The pathogenicity of tuber-borne inoculum was confirmed by growing plants from sclerotia-infested tubers. AG-8 isolates from diseased barley and wheat produced severe root cankers and caused loss of feeder roots on inoculated potato plants. Results suggest that rhizoctonia disease in potato fields in South Australia is caused by a combination of different anastomosis groups and this has important implications for crop rotations. 相似文献
6.
ABSTRACT Rhizoctonia solani anastomosis group (AG)-13 was collected from diseased roots of field grown cotton plants in Georgia in the United States. Isolates of AG-13 did not anastomose with tester isolates of AG-1 through AG-12. Mycelium of all isolates of AG-13 were light brown but darkened as cultures aged. All isolates produced aerial mycelium. Concentric rings were visible after 3 to 4 days of growth but disappeared as cultures aged and darkened. Individual sclerotia were up to 1.5 mm in diameter, similar in color to the mycelium, and generally embedded in the agar. Clumps of sclerotia up to 5 mm in diameter were produced on the agar surface. All attempts to induce basidiospore production were unsuccessful. The 5.8S region of the rDNA from isolates of AG-13 was identical in length and sequence to isolates of all other AGs of R. solani. Length and sequence of the internal transcribed spacer (ITS) regions of rDNA from isolates of AG-13 were unique among AGs of R. solani. Similarity between AG-13 and other AGs of R. solani ranged from 68 to 85% for ITS region 1 and 85 to 95% for ITS region 2. Selected isolates of AG-13 caused minor or no damage to barley, cauliflower, cotton, lettuce, potato, and radish in laboratory or greenhouse studies. 相似文献
7.
茄科蔬菜立枯丝核菌的融合群鉴定 总被引：3，自引：0，他引：3
Sixty-five samples were collected from rhizosphere soil, hot pepper and tomato plants showing damping-off, root rot and stem rot in Taian, Shouguang of Shandong province and Zhouzhi, Taibai of Shaanxi province. Thirty-nine Rhizoctonia solani isolates were obtained from these samples. The results of anastomosis group (AG) identification and sequence analysis of 5.8S rDNA-ITS of the isolates showed that thirty-six isolates (92.3%) belonged to AG-4, while only three (7.7%) belonged to AG-5. The isolates of AG4 could further be divided into two subgroups of AG4-HG-Ⅰ and AG4-HG-Ⅲ. The 5.8S rDNA-ITS sequences of the selected isolates of the two subgroups had the 99%-100% identity with standard isolates of AG4-HG-Ⅰ and AG4-HG-Ⅲ (from GenBank). Among the analyzed isolates, AG4-HG-Ⅰ subgroup was the dominant with the frequency of 79.5%. Subgroup AG-4-HG-Ⅲ with the frequency of 12.8% was the second. This is the first report that subgroup AG4-HG-Ⅲ of R. solani isolated from Solanaceae vegetable crops in China. 相似文献
8.
ABSTRACT Crater disease (CD) of wheat is caused by a Rhizoctonia solani strain of ambiguous phylogeny. Anastomosis reactions confirmed placement of CD-causing R. solani in anastomosis group (AG) 6, with results indicating a closer affinity to AG-6 GV than to AG-6 HG. Cultures of CD isolates were initially white to cream, turning a yellowish light brown after 10 days. Concentric rings of dark and light mycelium were evident from an early stage. Mycelium generally was appressed to the agar surface, with sparse aerial growth. A few light-colored, irregularly shaped sclerotia could be discerned after 2 weeks. The mean hyphal diameter of CD-causing R. solani was 7.46 mum (ranging from 5.0 to 10.0 mum), and cells contained a mean number of four (ranging from two to eight) nuclei, compared to a mean hyphal diameter of 8.58 and 8.42 mum and a mean nuclear number of six and four for AG-6 HG and AG-6 GV, respectively. The CD isolates had a slower growth rate (15.3 mm/day) than AG-6 HG (29.1 mm/day) and AG-6 GV (22.6 mm/day) but, like AG-6, were thiamine prototrophic. Conspicuous nodulose swellings were produced by CD-causing R. solani on roots of wheat, and infection resulted in retarded shoot growth. Smaller nodules were evident on bean and soybean roots. Fingerprint patterns generated for the various isolates with four enzymes, HpaII, Sau3AI, TaqI, and CfoI, showed the presence of a unique 610-bp fragment in the pathogen. It is proposed that CD-causing R. solani isolates represent a distinct intersterility group within AG-6 that is more related to subgroup GV than to subgroup HG. 相似文献
9.
Sixty-two isolates of Rhizoctonia spp. were collected from Belgian cauliflower fields during 2005 and 2006. The majority of the isolates (60 out of 62) had multinucleate cells and were identified as Rhizoctonia solani . Characterization of anastomosis groups (AGs) was performed using pectic zymograms, PCR-RFLP and sequencing of the rDNA-ITS region. The most prevalent AG was AG 2-1 (55% of isolates), followed by AG 2-1 subset Nt (11%), AG 1-1C (8%), AG 5 (8%), AG 4 HGII (6%), AG 3 (5%) and AG 1-1B (3%). Pathogenic potential towards different vegetable crops and towards maize was determined. Damage to cauliflower and endive was caused by different AGs, with the isolates aggressive towards cauliflower belonging to AG 2-1, AG 2-1 subset Nt, AG 4 HGII, AG 1-1C, AG 1-1B and AG 2-2, and those aggressive towards endive belonging to AG 1-1B, AG 1-1C, AG 2-1 subset Nt, AG 2-2, AG 4 HGII and AG 5. The most aggressive isolates towards bean belonged to AG 2-1 subset Nt and AG 2-2, for lettuce to AG 1-1B and AG 2-1, on carrot to AG 4 HGII and towards maize to AG 2-2. Within the isolates of AG 2-1, variability was observed in PCR-RFLP pattern and in aggressiveness towards several crops, indicating this subgroup to be heterogeneous. This is the first study concerning the occurrence of R. solani AGs causing wirestem in Belgian cauliflower fields and the first report of aggressive isolates of AG 1-1C, AG 2-1 subset Nt and AG 4 HGII associated with cauliflower. 相似文献
10.
中国中部5省(市)草坪禾草立枯丝核菌的菌丝融合群研究 总被引：4，自引：0，他引：4
2003~2005年,从我国冷季型草坪与暖季型草坪过渡地区的上海市、浙江省、山东省、河南省和陕西省草坪褐斑病的病株样本中,分离得到了43个立枯丝核菌分离物,其寄主包括多年生黑麦草(Lolium perenne)、高羊茅(Festuca arundina-cea)、草地早熟禾(Poa pratensis)、匍匐翦股颍(Agrostis palustris)、结缕草(Zoysia japonica)和狗牙根(Cynodon dactylon)。按照Parmeter等的方法对该过渡带的草坪禾草立枯丝核菌分离物进行了菌丝融合群的测定,结果表明,上述5省(市)草坪禾草立枯丝核菌的菌丝融合群包括AG1-1A、AG1-1B、AG2-1、AG2-2ⅢB、AG2-2Ⅳ、AG-4和AG-5。不同省份、不同寄主草坪禾草的菌丝融合群类型略有不同,主要融合群类型为AG-1和AG-2。AG1-1B和AG2-1是草坪上首次报道的立枯丝核菌融合(亚)群。 相似文献
11.
ABSTRACT Profiles of fatty acids from 70 isolates of Rhizoctonia solani anastomosis group (AG)-4 clustered into three groups, corresponding to homogeneous group (HG)-I, HG-II, and a newly described HG-III. Isolates from Georgia peanuts exhibiting limb rot were characterized as gas chromatography (GC) subgroup 1 (GC-1) and contained HG-I isolates. Isolates from diseased soybean hypocotyls grown in North Dakota and sugar beet seedlings, taproots, and tare soil in Minnesota and North Dakota were characterized as GC subgroup 2 (GC-2) and contained predominantly HG-II isolates but also included three distinct isolates based on fatty acid methyl ester (FAME) analysis and morphological features. Selected isolates from North Carolina cucumbers clustered into three distinct groups that corresponded to HG-I, HG-II, and the newly described HG-III. Distinct isolates from the soybean and sugar beet populations clustered with HG-III. Fatty acid profiles of AG-4 were compared with FAME library profiles of AG-1, AG-2 type 2, and AG-3, which were developed in previous studies and were sufficiently different that they could be used to support speciation of this group from R. solani. It is suggested that binomial R. practicola may be appropriate for the portion of AG-4 identified as HG-II. 相似文献
12.
Achmadi PRIYATMOJO Ryo YAMAUCHI Koji KAGEYAMA Mitsuro HYAKUMACHI 《Journal of General Plant Pathology》2002,68(1):1-7
Cellular fatty acids were analyzed to characterize and differentiate 34 isolates of Rhizoctonia species representing binucleate Rhizoctonia AG-D (I), AG-D (II), R. solani AG 2-2 IIIB, AG 2-2 LP, R. circinata var. circinata and var. oryzae associated with turfgrass diseases in Japan. Myristic, pentadecanoic, palmitic, palmitoleic, stearic, oleic, linoleic and
linolenic acids were consistently present in varying quantities in all isolates. Heptadecanoic and 9-heptadecenoic acids were
present in isolates of Rhizoctonia AG-D (I), AG-D (II), R. solani AG 2-2 IIIB and AG 2-2 LP but not in isolates of R. circinata var. circinata and var. oryzae. Palmitic, oleic and linoleic acids were the major fatty acids found, constituting 88.30-98.37% of the whole-cell fatty acid
content. The remaining fatty acids were present in smaller amounts. Isolates within a single group were closely clustered,
whereas isolates from different groups were clearly distinguishable based on average linkage cluster analysis of cellular
fatty acids. Principal component analysis, based on all fatty acids detected, confirmed the distinct separation of isolates
representing the six groups of Rhizoctonia species obtained from turfgrasses. These results suggested that fatty acid analysis is useful for the characterization and
differentiation of isolates of Rhizoctonia species associated with turfgrass diseases.
Received 21 May 2001/ Accepted in revised form 28 September 2001 相似文献
13.
Shiro KUNINAGA Donald E CARLING Toru TAKEUCHI Ryozo YOKOSAWA 《Journal of General Plant Pathology》2000,66(1):2-11
Genetic diversity among 51 isolates of Rhizoctonia solani AG-3, representing potato and tobacco populations, was inferred from the sequences of the internal transcribed spacer (ITS)
and 5.8S ribosomal RNA (rRNA) gene. The 5.8S rDNA sequence was completely conserved not only in AG-3, but across all the AG
isolates examined, whereas the rDNA-ITS sequence was found to be variable among the isolates. The nucleotide sequence similarity
in the ITS 1 region was high (96-100%) for isolates within each of the two populations, but was 91-92% for isolates from different
populations. The AG-3 isolates had 56 to 91% sequence similarities in the ITS 1 region with R. solani isolates of the other AGs. Phylogenetic analysis based on the ITS-5.8S rDNA sequence data indicated that the different populations
in AG-3 are distantly related to each other. Genetic divergence between the two populations was also supported by the results
of DNA-DNA hybridization studies. This study suggests that AG-3 consists of two genetically isolated groups corresponding
to separate subgroups: AG-3 PT (potato type) and AG-3 TB (tobacco type). Specific primer sets for the detection of the two
AG-3 subgroups were developed from the aligned rDNA-ITS sequences.
Received 22 April 1999/ Accepted in revised form 2 July 1999 相似文献
14.
ABSTRACT The induction of disease-suppressive soils in response to specific cropping sequences has been demonstrated for numerous plant-pathogen systems. The role of host genotype in elicitation of the essential transformations in soil microbial community structure that lead to disease suppression has not been fully recognized. Apple orchard soils were planted with three successive 28-day cycles of specific wheat cultivars in the greenhouse prior to infestation with Rhizoctonia solani anastomosis group (AG)-5 or AG-8. Suppressiveness to Rhizoctonia root rot of apple caused by the introduced isolate of R. solani AG-5 was induced in a wheat cultivar-specific manner. Pasteurization of soils after wheat cultivation and prior to pathogen introduction eliminated the disease suppressive potential of the soil. Wheat cultivars that induced disease suppression enhanced populations of specific fluorescent pseudomonad genotypes with antagonistic activity toward R. solani AG-5 and AG-8, but cultivars that did not elicit a disease suppressive soil did not modify the antagonistic capacity of this bacterial community. When soils were infested prior to the initial wheat planting, all cultivars were uniformly susceptible to R. solani AG-8. However, when pathogen inoculum was added after three growth-cycles, wheat root infection during the fourth growth-cycle varied in a cultivar specific manner. The same wheat cultivar-specific response in terms of transformation of the fluorescent pseudomonad community and subsequent suppression of Rhizoctonia root rot of apple was observed in three different orchard soils. These results demonstrate the importance of host genotype in modification of indigenous saprophytic microbial communities and suggest an important role for host genotype in the success of biological control. 相似文献
15.
Aetiology of Rhizoctonia in sheath blight of maize in Sichuan 总被引：1，自引：0，他引：1
Rhizoctonia isolates obtained from maize grown in commercial fields in 33 representative counties (or cities) in Sichuan province in China were characterized according to colony morphology, hyphal anastomosis and pathogenicity. Of 141 isolates, 116 were identified as R. solani , 23 as R. zeae and two as binucleate Rhizoctonia . The isolates of R. solani were assigned to four anastomosis groups (AG): AG-1-IA (101 isolates, accounting for 71.6% of the total), AG-1-IB (2, 1.4%), AG-4 (9, 6.4%) and AG-5 (4, 2.8%). The two isolates of binucleate Rhizoctonia belonged to AG-K. On maize, isolates of AG-1-IA caused typical sheath blight symptoms. Lesions produced by isolates of AG-4, AG-5, AG-1-IB and AG-K were darker than those of AG-1-IA. Rhizoctonia zeae usually caused discontinuous lesions with a dark brown margin and a brown centre on the leaf sheaths, as well as ear rot. Isolates of AG-1-IA were the most virulent to maize, with an average lesion length of approximately 15 cm. Isolates of R. zeae produced lesions approximately 12 cm long, while those of AG-4, AG-5, AG-1-IB and AG-K were progressively shorter. On potato dextrose agar (PDA; pH 6.4), the minimum temperature for mycelial growth of R. zeae isolates was 14–18°C, the maximum 38–40°C and optimum 30°C. Isolates of R. zeae did not grow on PDA (28°C) at pH 2.0, the optimum for growth being pH 6.4. 相似文献
16.
ABSTRACT Root and stem rot of cut-flower roses (Rosa spp.) was observed in commercial glasshouse-grown roses in 10 prefectures of Japan from 1998 through 2001. Binucleate-like Rhizoctonia spp. were isolated mainly from the disease plants. In all, 670 isolates were divided into two types based on cultural appearance; 168 isolates of light brown to brown type and 502 isolates of whitish type. A hyphal anastomosis reaction using representative isolates from each type revealed that the light brown to brown type belonged to anastomosis group G (AG-G), whereas the whitish type (AG-CUT) failed to anastomose with tester strains of binucleate Rhizoctonia AG-A through AG-S. Neither isolates of AG-G nor AG-CUT anastomosed with tester strains of a previously reported unknown AG (AG-MIN) of binucleate Rhizoctonia spp. collected from miniature roses. In pathogenicity tests, randomly selected isolates of the three groups caused root and stem rot on cut-flower and miniature roses. To differentiate AG-CUT and AG-MIN from known AGs of binucleate Rhizoctonia spp., restriction fragment length polymorphism (RFLP) and sequence analyses of a ribosomal (r)DNA internal transcribed spacer (ITS) region were conducted. Among the eight restriction enzymes used, HaeIII produced DNA banding patterns for AG-CUT that differed from those of tester strains and AG-MIN. Additionally, restriction profiles of AG-MIN differed from those of all tester strains. AG-G isolates from cut-flower roses had the same RFLP pattern as the tester strains of AG-G. Based on the results of hyphal anastomosis and RFLP and sequence analysis of an rDNA-ITS region, we propose that AG-CUT be designated AG-T and AG-MIN be designated AG-U, two new AGs of binucleate Rhizoctonia spp. The phylogenetic tree based on the sequence data of the rDNA-ITS region showed that isolates of AG-MIN were in a distinct clade from other AGs, whereas isolates of AG-CUT were in the same clade as those of AG-A. More detailed phylogenetic analysis besides rDNA-ITS region might be necessary for AG classification of binucleate Rhizoctonia spp. 相似文献
17.
小麦纹枯病菌核糖体基因内转录区序列比较 总被引：13，自引：1，他引：12
对7个从江苏省小麦纹枯病样本分离到的丝核菌菌株,进行形态学鉴定、融合群分类和致病性测定,提取病菌的DNA,采用通用引物ITS1(TCC GTA GGT GAA CCT GCG G)和ITS4(TCC TCC GCT TAT TGA TAT GC),扩增病菌的rDNA内转录区(ITS),并对扩增产物进行了测序.用这些序列在NCBI中进行BLAST分析,得到与这些菌株亲缘关系最近的菌株序列,并明确了这些菌株的分类地位.对以上的菌株序列进行Alignment分析,结果表明,病菌的5.8S rDNA序列高度保守,而ITS区的可变性则相对较高,在双核和多核丝核菌、双核丝核菌CAG1融合群和非CAG1融合群菌株间存在差异,可用于反映菌株间的进化关系和双核丝核菌种下分类. 相似文献
18.
ABSTRACT A murine hybridoma cell line GD2 secreting an immunoglobulin (Ig)M monoclonal antibody (MAb) was produced against surface antigens from an anastomosis group (AG) 4 isolate of Rhizoctonia solani (teleomorph: Thanatephorus cucumeris). Ascites were produced in mice using GD2 hybridoma cells and used to develop a rapid immunochromatographic lateral flow device (LFD) for the detection of antigens from R. solani and certain related Rhizoctonia spp. The LFD was tested for specificity against surface antigens from related and unrelated soil fungi. Antigens from representative isolates of R. solani AGs 1, 2-1, 2-3, 2-t, 3, 4, 5, 6, 7, 8, 9, 10, 11, and BI gave a positive response in LFD tests, as did antigens from Thanatephorus orchidicola, T. praticola, R. fragariae (teleomorph: Ceratorhiza fragariae), Ceratorhiza goodyerae-repentis, Ceratobasidium cornigerum, and binucleate AGE. Antigens from R. solani AGs 2-2, 2-2IIIB, and 2-2IV and from the related fungi R. carotae, R. cerealis (teleomorph: Ceratobasium cereale), R. crocorum (teleomorph: Helicobasidium brebissonii), R. oryzae (teleomorph Waitea circinata), and R. zeae gave negative responses, as did antigens from a range of unrelated fungi and oomycetes including Fusarium, Gliocladium, Trichoderma, Pythium, and Phytophthora spp. The usefulness of the LFD to detect R. solani was demonstrated in soils naturally infested with R. solani AG3. There was close agreement between results of LFD tests and conventional plate enrichment tests employing selective medium. The specificity of the technique was confirmed by polymerase chain reaction PCR using R. solani AG3-specific primers and by analyses based on sequences of the internal transcribed spacer (ITS)1-5.8S-ITS2 rRNA-encoding regions of unrelated fungi recovered from soil samples. The LFD was used to quantify R. solani AG4 in artificially infested soil samples (chopped potato soil inoculum). Estimates of CFU per gram of soil were derived using a most-probable number technique, which was based on the presence or absence of a detectable signal in the LFD. Estimates of CFU obtained in LFD tests and those obtained in a plate-trapped antigen enzyme-linked immunosorbent assay incorporating MAb GD2 were identical (449 CFU g(-1) of soil). 相似文献
19.
20.
J.H.M. Schneider O. Salazar V. Rubio J. Keijer 《European journal of plant pathology / European Foundation for Plant Pathology》1997,103(7):607-622
Methods based on internal transcribed spacers (ITS) ribosomal DNA (rDNA) polymorphism and pectic zymograms (ZG) were compared for their use in routine identification of Rhizoctonia solani isolates occurring in flower bulb fields. Thirty three AG 2-t isolates, pathogenic to tulips, could be distinguished from AG 1-IC, AG 2-2IIIB and AG 2-2IV, AG 3 and AG 5 by means of ITS rDNA fragment length and after digestion with EcoR I from AG 4 and AG 5. AG 2-t isolates and two Japanese isolates, pathogenic to crucifers and tulips, had an estimated fragment size of 710 bp, whereas Dutch AG 2-1 isolates, non-pathogenic to tulips, showed an estimated fragment size of 705 bp on agarose gel. Digestion of AG 2-t and AG 2-1 isolates with EcoR I, Sau3A I, Hae III and Hinc II revealed four and five distinct ITS rDNA digestion patterns, respectively. In AG 2 isolates 2tR114, 21R14 and 21R61 a double digestion pattern, indicating different ITS sequences within an isolate, was found. The observed ITS fragment length polymorphism between isolates pathogenic and non-pathogenic to tulips were considered too small to be used in routine screening of field isolates. Sequencing of AG 2 isolates 21R01, 21R06, 2tR002 and 2tR144 showed a total ITS rDNA fragment length of 715, 713, 714, and 728 bp. As an alternative to ITS rDNA fragment length polymorphism, pectic enzyme patterns were studied using a commercially available vertical gel-electrophoresis system and non-denaturing polyacrylamide gels amended with pectin. Anastomosis tester isolates AG 1 to AG 11 revealed different ZG. Fifty AG 2-t isolates and five AG 2-1 isolates belonged to a homogeneous pectic zymogram group. We propose to assign AG 2 isolates pathogenic to crucifers and tulip to ZG5-1. AG 2-1 isolates, non-pathogenic to tulip, formed a heterogeneous group with 4 distinct ZG. Pectic zymography provides an easy, quick and unambiguous method for routine identification of large numbers of field isolates. Such a technique is needed for research on the dynamics of Rhizoctonia populations to develop environmentally friendly control measures of rhizoctonia disease in field-grown flower bulbs. 相似文献