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1.
Vibrio cholerae isolates recovered from cholera outbreaks in Bhind district of Madhya Pradesh and Delhi, Northern India were characterized. The O1 serogroup isolates from Bhind outbreak were of Inaba serotype whereas both Ogawa and Inaba serotypes were recovered from Delhi. PCR analysis revealed that only O1 serogroup V. cholerae isolates carried the virulence-associated genes like ctxA, tcpA, ace, and zot. Molecular typing by repetitive sequence based ERIC, VCR1, and VC1 PCR’s revealed similar DNA profile for both Inaba and Ogawa serotypes. A discrete VC1-PCR band identified among the El Tor strains had greater similarity (>97%) to the V. cholerae genome sequence and therefore has the potential to be used as a marker for the identification of the V. cholerae strains. Non-O1 strains recovered from Bhind region differed among themselves as well as from that of the O1 isolates. All the O1 serogroup isolates possessed SXT element and were uniformly resistant to the antibiotics nalidixic acid, polymyxin-B, furazolidone, cloxacilin, trimethoprim-sulfamethaxazole, and vibriostatic agent 0129. Inaba strains from both Delhi and Bhind differed from Ogawa strains by their resistance to streptomycin despite sharing similar DNA patterns in all the three rep-PCRs. Though Delhi and Bhind are separate geographical regions in Northern India, Inaba strains from both these places appear to be closely related owing to their similarity in antibiogram and genetic profile.  相似文献   

2.
Deimatic displays, where sudden changes in prey appearance elicit aversive predator reactions, have been suggested to occur in many taxa. These (often only putative) displays frequently involve different components that may also serve antipredator functions via other mechanisms (e.g., mimicry, warning signalling, body inflation). The Colombian four-eyed frog, Pleurodema brachyops, has been suggested to gain protection against predation through putative deimatic displays where they inflate and elevate the posterior part of their body revealing eye-like colour markings. We exposed stationary artificial frogs to wild predators to test whether the two components (eyespot/colour markings, defensive posture) of their putative deimatic display, and their combination, provide protection from predation without the sudden change in appearance. We did not detect any obvious additive effect of defensive posture and eyespots/colour markings on predation risk, but found a marginally significant trend for model frogs in the resting posture to be less attacked when displaying eyespots/colour markings than when they were not, suggesting that the presence of colour markings/eyespots may provide some protection on its own. Additionally, we found that models in a resting posture were overall more frequently attacked on the head than models in a defensive posture, indicating that a defensive posture alone could help redirect predator attacks to non-vital parts of the body. The trends found in our study suggest that the different components of P. brachyops' coloration may serve different functions during a deimatic display, but further research is needed to elucidate the role of each component when accompanied by sudden prey movement.  相似文献   

3.
Twelve isolates of Lasiodiplodia theobromae were collected from 12 different commercial banana cultivars belonging to various banana growing regions of Tamil Nadu, India. The results revealed that most of the L. theobromae isolates exhibited significant differences in morphology, colour and spore size. However, all 12 isolates took 3–4 days invariably to cover the 90 mm Petri plates. Among the 12 isolates, the isolates LT3a from Robusta and LT10c from dwarf Cavendish produced abundant pycnidia. These isolates were also analysed through Random amplified polymorphic DNA (RAPD) markers for genetic diversity. Polymerase chain reaction amplification of total genomic DNA of the 12 isolates of L. theobromae with 14 random primers generated numerous polymorphisms among the isolates, while many of the intense bands were shared among majority of the isolates. Cluster analysis also indicated a high degree of genetic variability within L. theobromae isolates from different banana cultivars. The 12 isolates were separated into three clusters namely A, B and C. The maximum similarity index of 80% was recorded between the isolates LT7d from Karpuravalli and LT10c from dwarf Cavendish. The least similarity index of 29.41% was recorded with the isolates LT1f isolated from Poovan and LT5a isolated from Virupakshi. Within the species of L. theobromae the genetic variability was high and it underlines and validates existence of significant intra-specific diversity in isolates of L. theobromae infecting different banana cultivars.  相似文献   

4.
Aims: Aim of this study is to determine the genetic variation of rhizobia associated with horse gram [Macrotyloma uniflorum (Lam.) Verdc.] plants grown in different regions of Andhra Pradesh, India. Methods and Results: Four representative isolates having most representative characters from the previous characterization were selected for 16S rRNA sequence. The sequences were submitted to the NCBI GenBank and Ribosomal Database Project (RDP). The isolates HGR‐4, 6 and 13 showed more than 99% homology between them and they were grouped with Rhizobium reference strains where as the isolate HGR‐25 showed 87·1, 87·4 and 87·2% homology with the isolates HGR‐4, 6 and 13, respectively, and were grouped with reference strains for Caulobacter. The nodulation ability of these isolates on horse gram was confirmed by inoculation tests. Conclusions: The isolate HGR‐25 was identified as Caulobacter isolated from the plants growing in soil samples collected from Khareemnagar district, Andhra Pradesh, India. Inoculation tests revealed that Caulobacter formed nodules on horse gram. It was also confirmed by RDP. Significance and Impact of the Study: This is the first report that a legume was nodulated by a member of the genus Caulobacter, which belongs to the family Caulobacteriaceae in the order Caulobacterales of Alphaproteobacteria.  相似文献   

5.
Book Review     
To study the variability and to identify the species of Begomovirus associated with yellow mosaic disease of blackgram in Andhra Pradesh, India, infected blackgram samples were collected from six districts belonging to three regions of Andhra Pradesh. The total DNA was isolated by modified CTAB method and amplified with coat protein gene-specific primers (RHA-F and AC abut) resulting in 900?bp gene product. The PCR products were cloned, sequenced and deposited in GenBank. The sequence analysis of six clones showed that the size of amplified CP gene of YMV was 920?bp. Based on nucleotide sequence identity of six isolates representing three regions of Andhra Pradesh, the isolates from Rayalaseema and Telangana region are the same variant of YMV (>99.5% identity) and isolate from coastal Andhra is another variant of YMV (>95.4%) when compared with other region isolates. Comparison of CP gene sequence of YMV-TPT isolate with 27 other isolates in database revealed more than 93.2 and 86.2% identity with MYMIV isolates and less than 80 and 64% identity with MYMY isolates that originate from Indian sub-continent and South-East Asia at nucleotide and amino acid level, respectively. Phylogenetic tree based on CP gene sequences of six isolates with other isolates from GenBank formed unique cluster with MYMIV. Hence the YMV infecting blackgram in Andhra Pradesh is caused by MYMIV rather than MYMY as reported in Tamil Nadu which is adjoining state in southern India.  相似文献   

6.
Abstract

Fifteen pathogenic isolates of Helminthosporium oryzae were established from 15 different rice growing areas representing nine districts: Madurai, Theni, Thanjavur, Thiruvarur, Nagapatinum, Tirunelveli, Trichy, Ariyalur and Cuddalore district of Tamil Nadu. The symptoms initially appeared on the leaves as small, oval, dark brown to black spots. Under favourable conditions, the fungus attacks grain and caused grain discoloration. The isolate, collected from Ammapettai of Thanjavur district was the most virulent (Grade 7.47, PDI 82.96) on rice plants followed by Trichy isolate I2 (Grade 7.26; PDI 80.74) while I15 (Cumbum) was the least virulent (Grade 1.8, PDI 20.00). The isolates of H. oryzae varied in size (length and width) of the conidia, colour and the number of cells per conidium. The maximum (39.1 μm) length of the conidium was observed in I10 followed by I11 (37.3 μm). The maximum (17.1 μm) conidial width was observed in I8. The colour of the conidium varied from light brown (isolates I3, I6 and I14) to brown, while there was no appreciable difference in the conidial shape. The number of cells varied from 2 – 4 among the isolates. Six phylloplane microorganisms were tested against the virulent isolate of H. oryzae. Among them, Cladasporium spp was very effective in inhibiting the mycelial growth and spore germination of H. oryzae followed by Penicillum spp and Aspergillus flavus while Bacillus subtilis was least effective in inhibiting the mycelial growth and spore germination of H. oryzae.  相似文献   

7.
This is the first report about charcoal rot disease in Jordan. Twenty-five Macrophomina phaseolina isolates were collected from infected plants showing typical symptoms of charcoal rot disease. All of the 25 M. phaseolina isolates were pathogenic to cucumber plants under green house effect. The amplification of the isolated DNA from the 25 pathogenic fungal cultures using ITS specific primers (ITS 1?+?ITS 4) showed a single band of 580?bp. There was a significant variation of their mycelial linear growth rate on PDA medium. The 25 M. phaseolina isolates showed a wide heterogeneity in their mycelium colour, microsclerotia distribution, pycnidia formation and chlorate phenotypes. Based on the morphological characterisation, the 25 isolates were grouped into seven different groups as indicated in a dendrogram of their morphological variation. The overall means similarity matrix of the 25 M. phaseolina recovered isolates were 0.58. The means of similarity matrix of the 25 M. phaseolina was in between 0.83 and 0.14. The similarity coefficient between the 25 isolates varies between 0.27 and 1.0.  相似文献   

8.
Exudates from sclerotia of two Sclerotium rolfsii isolates (one causing collar rot in Cicer arietinum, isolate VC971, and the other leaf spots in Rauvolfia serpentina, isolate VL016) were assayed for their antifungal activity against 26 fungi consisting of plant parasites as well as saprophytes. Spore germination of all the test fungi was affected by the exudates reaching 100% in some cases. Foliar spray with exudates of isolate VL016 significantly reduced disease incidence of balsam (Impatiens balsamina) powdery mildew caused by Erysiphe cichoracearum and pea (Pisum sativum) powdery mildew caused by Erysiphe pisi, under field conditions. Characterization of exudates from 25 isolates of S. rolfsii revealed pH ranging from 3.8 to 5.3 and colour from light yellow to deep yellow. Among the phenolic acids found in the exudates were tannic, gallic, caffeic, vanillic, ferulic, chlorogenic and cinnamic acids. Oxalic acid was also found in varied amounts. Among the phenolic acids, ferulic acid was found to be present at high concentration in exudates of most isolates (3.9–153.4 μg/ml). The antioxidant properties of phenolics, which generally inhibit fungal morphogenesis including spore germination along with the antifungal nature of some phenolics are chiefly attributed to the inhibitory effect of sclerotial exudates of S. rolfsii. Additionally, both the isolates VC971 and VL016 showed almost similar antifungal activities despite they are of different origin and thereby demonstrate the antifungal nature of sclerotial exudates.  相似文献   

9.
Traditionally, the distribution of the Mycobacterium tuberculosis genotypes in India has been characterized by widespread prevalence of ancestral lineages (TbD1+ strains and variants) in the south and the modern forms (TbD1(-) CAS and variants) predominating in the north of India. The pattern was, however, not clearly known in the south-central region such as Hyderabad and the rest of the state of Andhra Pradesh where the prevalence of both tuberculosis (TB) and human immunodeficiency virus (HIV) infection is one of the highest in the country; this area has been the hotspot of TB vaccine trials. Spoligotyping of 101 clinical isolates obtained from Hyderabad and rural Andhra Pradesh confirmed the occurrence of major genogroups such as the ancestral (or the TbD1+ type or the East African Indian (EAI) type), the Central Asian (CAS) or Delhi type and the Beijing lineage in Andhra Pradesh. Sixty five different spoligotype patterns were observed for the isolates included in this study; these were further analyzed based on specific genetic signatures/mutations. It was found that the major genogroups, CAS and "ancestral," were almost equally prevalent in our collection but followed a north-south compartmentalization as was also reported previously. However, we observed a significant presence of MANU lineage in south Andhra Pradesh, which was earlier reported to be overwhelmingly present in Mumbai. This study portrays genotypic diversity of M. tuberculosis from the Indian state of Andhra Pradesh and provides a much needed snapshot of the strain diversity that will be helpful in devising effective TB control programs in this part of the world.  相似文献   

10.
Summary Slow-growing interspecific heterokaryons were isolated on minimal medium following the induced fusion of protoplasts from auxotrophic mutants of Penicillium chrysogenum and Penicillium cyaneo-fulvum. After 5–7 days cultivation the heterokaryons produced vigorously growing sectors which on transfer gave genetically stable colonies. Cultivation of these colonies on a complete medium supplemented with p-fluorophenylalanine or benomyl broke down this stability and several different prototrophic and auxotrophic colony types were isolated. Many of these behaved as diploids or aneuploids showing sectoring either spontaneously, or in the presence of an haploidizing agent. Some of the latter isolates were recombinants for parental spore colour and auxotrophic markers.  相似文献   

11.
The genomes of three potyvirus isolates from, respectively, naturally infected Colocasia esculenta, Caladium spp. and Dieffenbachia spp. in Andhra Pradesh, India, were amplified by RT‐PCR using degenerate potyvirus primers. Sequence analysis of RT‐PCR amplicons (1599 nucleotides) showed maximum identity of 97% with the KoMV‐Zan isolate of Konjac mosaic virus (KoMV) from Taiwan (A/C AF332872). The three isolates had a maximum identity of 99.4%. The length of coat protein (CP) gene of three isolates was 846 nucleotides encoding 282 amino acids with a deduced size of 32.25 kDa. The CP gene of the isolates had, respectively, 78.1–95.7% and 88.2–96.4% identity at nucleotide and amino acid levels with KoMV isolates. The CP gene of the three isolates had 93.1–100% (nucleotide) and 98.2–100% (amino acid) identity. The 3′‐UTR of the three isolates showed maximum identity of 91.1–100% identity between and with other KoMV isolates. In the CP amino acid–based phylogenetic analyses, the isolates branched as a distinct cluster along with known KoMV isolates. The three potyvirus isolates associated with mosaic, chlorotic feathery mottling, chlorotic spots, leaf deformation and chlorotic ring spots on three aroids were identified as isolates of KoMV for the first time from Andhra Pradesh, India.  相似文献   

12.
Electrophoretic karyotypes of different isolates of Plasmodiophora brassicae, the causative agent of clubroot of cabbage, using contour‐clamped homogeneous electric field gel electrophoresis (CHEF) revealed chromosome polymorphism in this obligate parasite. Ribosomal RNA (rRNA) genes have been localized on three chromosomes (I, IV and V) of P. brassicae of the 16 chromosomal bands, which can be distinguished for the single‐spore isolate ‘e3’. In comparison with this isolate three other single‐spore isolates showed chromosome polymorphism by size of chromosomal bands and by hybridization pattern with rRNA gene fragments and other Plasmodiophora‐specific DNA fragments.  相似文献   

13.
Madhya Pradesh is the major soybean contributor in India. The taxonomy of nitrogen fixing bacteria forming symbiotic associations with leguminous plants has been deeply changed in recent years. The use of very sensitive and accurate molecular methods has enabled the detection of large rhizobial diversity. Molecular biotyping and characterization the Bradyrhizobium, isolates from eleven varieties of soybean from agricultural field of Sehore district of Madhya Pradesh is done using 16S rDNA typing. Bradyrhizobia were identified genetically by determining the %Guanine plus Cytosine content of the whole genome, followed by 16S rDNA-RFLP analysis % Guanine plus Cytosine content of all the Bradyrhizobium isolates reflects similarity at generic level among all Bradyrhizobial isolates. Restriction Fragment Length Polymorphism (RFLP) further showed a considerable level of genetic diversity among the Bradyrhizobial isolates. PCR-RFLP of 16S rDNA supported existence of two divergent groups among indigenous Bradyrhizobial isolates, at similarity level of 66, and 75 and 74% of similarity within the group. The technique used was helpful in characterizing Bradyrhizobium isolates to be used as inoculants for improving productivity of agricultural land of Madhya Pradesh (India).  相似文献   

14.
Abstract

German wasps (Vespula germanica F.) and common wasps (V. vulgaris L.) both show variations in colour markings in New Zealand. Overlap in the ranges of markings of the head and thorax is limited enough for ready distinction of queens and workers of the two species. Abdominal markings overlap considerably between the species. Colour markings of males were too similar to identify the species, which were completely separated by the shape of their genitalia. The frequency of occurrence of “intermediate” markings in V. germanica populations did not increase in areas where the two species overlap. This suggests there is little or no genetic exchange between the two species.  相似文献   

15.
Wilt of chickpea (Cicer arietinum) caused by Fusarium oxysporum f. sp. ciceris is prevalent in almost all chickpea growing areas of the world and its incidence varied from 14.1 to 32.0% in the different states of India surveyed. The isolates were highly variable in their colony growth pattern, size of colony and pigmentations. The size of microconidia varied from 5.1–12.8 × 2.5–5.0 μm, whereas macroconidia ranged from 16.5–37.9 × 4.0–5.9 μm with 1–5 septations. One hundred and twelve isolates were grouped into 12 categories on the basis of their radial growth, size of macroconidia and growth pattern. Majority of the isolates were highly pathogenic causing more than 50% wilt in chickpea cultivar JG 62. Virulence analysis of 56 representative isolates on a set of 18 cultivars of chickpea, including 10 international differentials, grouped them into three categories. Chickpea cultivar KWR 108 differentiated all isolates of Punjab, Haryana and Delhi states and a few isolates of Rajasthan from others by showing resistant reactions and were placed in the first group. The rest of the isolates of Rajasthan state showed susceptible reactions on KWR 108 placed in a second group. Cultivar CPS 1 distinguished the isolates of Jharkhand state and placed them into a third group. An international set of cultivars recommended for race differentiation were not able to distinguish all the isolates into known races of the pathogen, therefore cultivar KWR 108 should be included in the existing differential set of cultivars.  相似文献   

16.
Abstract

Tomato Leaf Curl New Delhi Virus (ToLCNDV) is an important begomovirus constraint to the production of cucurbitaceous and other crops in India and its subcontinent. In this study first time, symptomatic samples of different cucurbits were collected from Telangana, Uttar Pradesh (Varanasi) and Madhya Pradesh location in India. The symptomatic samples were associated with begomovirus infection was confirmed by PCR amplification using specific universal primers Deng 540/541. Thirteen out of fifteen samples were amplified with newly designed bipartite specific primers JKR 58?F and JKR 59?R. In eleven out of thirteen bipartite samples contain betasatellite, confirmed by PCR amplification using specific primer CLB36F and CLB37R. The amplified PCR product with JKR58F and 59R of bitter gourd sample collected from Telangana was sequenced. The sequence was share 97.53% similarity with ToLCNDV infecting bottle gourd in Haryana in India (FN645905). Phylogenic analysis revealed that ToLCNDV infecting cucurbits are different, from ToLCNDV infecting tomato.  相似文献   

17.
The single‐spore isolates ‘e3’ and ‘e6’ of Plasmodiophora brassicae with different virulence patterns were distinguished by restriction fragment length polymorphisms in fingerprint‐like patterns and by electrophoretic karyotypes using repetitive fragments as hybridization probes. These molecular tools were used to characterize a set of isolates originated from an infected root, which was inoculated with a mixture of the two single‐spore isolates (e3 and e6). Spores harvested from mixed‐infected roots were used to establish 53 new single‐spore isolates. All these single‐spore isolates revealed parental patterns according to their molecular fingerprints and their virulence pattern. No sexual recombination could be detected with repetitive molecular probes. However, one isolate (M36ES49) showed the same fingerprint pattern and virulence pattern but different sizes of small chromosomes than the parental type ‘e6’, which is taken as an indication of chromosome rearrangement during the infection cycle.  相似文献   

18.
A total of 67 bacterial isolates were obtained from apple and pear fruits with signs of soft rot collected from Egyptian markets. Pathogenicity tests showed that 25 isolates (37%) were pathogenic to apple and pear fruits, with considerable variation of virulence. Among these isolates, 16 (64%) were Gram‐positive, motile, spore‐forming long rods and were identified as members of the genus Bacillus based on an API test. In addition, five isolates (20%) were Gram‐negative, non‐spore‐forming, motile, oxidase and catalase‐positive short rods and were identified as members of the genus Pseudomonas. Furthermore, four isolates (16%) were Gram‐negative, non‐spore‐forming, motile, catalase‐positive and oxidase negative short rods and were identified as belonging to the genus Erwinia. All selected isolates showed a wide host range and could cause soft rot of all representative fruits and vegetables tested. The three most virulent isolates, AB4, AB6 and PB6, exhibited the highest soft rot severity on different apple and pear cultivars, and apple cv. Anna (116) was the most susceptible to infection by isolates AB4 and AB6, with soft rot severities of 63.33 and 60.67%, respectively. Also, pear cv. Le‐Conte was most susceptible to infection by isolate AB6, with a soft rot severity of 89.9%. A phylogenetic tree based on 16S rRNA gene sequences indicated that strains AB4 and AB6 were very similar to one another and also showed a similarity of 99% to Bacillus altitudinis, and strain PB6 revealed a similarity of 99% to Bacillus pumilus. To our knowledge, this is the first report of B. altitudinis as a soft rot pathogen for both apple and pear fruits.  相似文献   

19.
This study was undertaken to characterize Streptomyces strains occurring in some soils of Tanzania as well as to evaluate their potential to synthesize antimicrobial compounds. Six main classes of isolates were observed according to the colour of aerial mycelium. These were gray, cream, blue, pink, red, and white. The gray colour class dominated. About 65% of the isolates produced soluble pigments of various colours while about 33% of the isolates did not produce any soluble pigments. Brown coloured soluble pigments dominated. About 57% of the isolates had spiral spore chains. Some Streptomyces isolates displayed strong (> 30 mm inhibition zone), moderate (20–30 mm), or weak (< 20 mm) antibiosis against the plant/animal pathogenic bacteria tested. Other isolates did not show any antibiosis against any of the test pathogens. The plant pathogens CMM IPO 542 (Clavibacter michiganensis ssp. michiganensis) and Xanthomonas vascatoria were inhibited by most of the Streptomyces isolates. Xanthomonas oryzae pv. oryzae and X. campestris were inhibited by the least number of the Streptomyces isolates. Most of the animal pathogens tested seemed to show resistance to the antibiotics produced by some of the Streptomyces isolates which had shown high activity against the plant pathogens. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

20.
Fruit rot of chillies (Capsicum annuum L.), caused by Colletotrichum capsici under tropical and subtropical conditions, results in qualitative and quantitative yield losses. Based on variation in cultural and morphological traits of C. capsici populations, 37 isolates were categorized into five groups designated, respectively, as Cc‐I, Cc‐II, Cc‐III, Cc‐IV and Cc‐V. In culture, most of the isolates produced cottony, fluffy or suppressed colonies. However, no significant differences were noticed in shape and size of conidia. The reaction of the 37 isolates on an indigenously developed differential set of Capsicum cultivars indicated the existence of different virulences in Himachal Pradesh (HP) chilli populations. Fifteen pathotypes of the pathogen were characterized from various chilli‐growing regions of HP. Pathotype CCP‐1 was most virulent and attacked all the differential cultivars. The genetic relationship between five morphological groups recognized within C. capsici was investigated using random amplified polymorphic DNA (RAPD) analysis. Molecular polymorphism generated by RAPD confirmed the variation in virulences of C. capsici and different isolates were grouped into five clusters. However, four isolates (Cc‐5, Cc‐33, Cc‐29 and Cc‐37) exhibited identical RAPD haplotypes. The pathological and RAPD grouping of isolates suggested no correlation among the test isolates.  相似文献   

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