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1.
Immature zygotic embryo cultures of neem yielded highly regenerative cultures, with the response varying with the embryo stage at culture. Early dicotyledonous stage embryos were the most responsive followed by torpedo stage embryos. The embryo cultures differentiated three types of regenerants: somatic embryos (SEs), shoot buds and neomorphs. SEs exhibited morphological abnormalities such as pluricotyledony, fusion of cotyledons and absence of cotyledons. Although these SEs showed secondary embryogenesis, the occurrence of normal dicotyledonous embryos was extremely rare. On MS basal medium 3% of SEs developed a long tap root but a plumular shoot did not appear. However, it was possible to regenerate plantlets from immature zygotic embryo cultures of neem via neomorph formation and adventitious shoot bud formation. The transplantation survival of these plants was more than 80%.Abbreviations BAP 6-Benzylamino purine - CH Casein hydrolysate - 2,4-D 2,4-Dichlorophenoxyacetic acid - GA3 Gibberellic acid - IAA Indole-3-acetic acid - IBA Indole-3-butyric acid - NAA -Naphthaleneacetic acid - SE Somatic embryoCommunicated by W. Harwood  相似文献   

2.
The inhibition of mycelial growth of Lagenidium giganteum by neem oil was lower than that of Metarhizium anisopliae in PYG and Emerson’s YpSs agar media. However, neem oil did not inhibit the mycelial growth of L. giganteum in sunflower seed extract agar medium, but did it inhibit the mycelial growth of M. anisopliae. The minimum inhibitory concentration of neem oil for L. giganteum was higher than that for M. anisopliae. The minimum fungicidal concentration of neem oil in PYG medium was lower than in YpSs for both fungi. The spores of L. giganteum grown in SFE medium could be used with neem oil for vector control.  相似文献   

3.
A process with controlled pattern of regenerant differentiation from leaflet segments leading to production of cloned plants of a 40-year-old tree of Azadirachta indica was developed. A two-step procedure was adopted for containing intervening callusing during regenerant differentiation using modified Murashige and Skoog (MS) medium, where in the first step the explants were subjected to pulse treatments having higher concentration of 6-benzylaminopurine (BAP), while in the second step they were cultured in one-tenth of the initial concentrations of BAP. In the present case, simultaneous differentiation of two types of morphogenetic structures, that is, shoot buds and the meristematic nodules was observed. However, differentiation of higher number of desirable regenerants—the shoot buds and a few meristematic nodules, rather than vice-versa could be controlled by increasing both, the concentration of BAP in pulse treatment and the duration of pulse treatment. In the optimum treatment, where the explants were exposed to 8.88 μM BAP and 81.43 μM adenine hemisulphate for 5 days followed by their transfer to 0.88 μM BAP and 81.43 μM adenine hemisulphate, on an average, 17.4 shoot buds and only 1.6 meristematic nodules were formed from a leaflet. On subculturing, the shoot buds developed into shoots, whereas the meristematic nodules produced three kinds of organized structures that too in varied proportions. Multiplication of shoots was sustained in proliferation medium supplemented with 1.11 μM BAP, 1.43 μM indole-3-acetic acid (IAA) and 135.72 μM adenine hemisulphate. The isolated shoots were rooted and complete plantlets were transferred to potted soil with 100% survival.  相似文献   

4.
Fifteen-day-old variety NA 56-79 sugar cane seedlings were inoculated with Azospirillum brasilense and Glomus intrarradix. This article aims at examining changes in sugar cane root seedlings inoculated with Glomus intrarradix and Azospirillum brasilense, the increase in microbial biomass and the acetylene reduction process as well. The internal root colonization was studied 20 days after inoculation using scanning and a transmission electron microscope. Both microorganisms entered the sugar cane root through the emergent lateral roots. The microorganisms were capable of coexisting both intra and intercellularly, producing changes in the cell wall, thus allowing colonization and interaction between the organisms. These changes increased the number of microorganisms inside the root as well as acetylene nitrogen reduction. Sugar cane plant biomass increased with joint-inoculation. The number of endophytic microorganisms and nitrogen fixing activity increased when they were colonized by Azospirillum and Glomus together.  相似文献   

5.
The present study on efficacy of different Glomus species, an arbuscular mycorrhizal (AM) fungus (G. aggregatum, G. fasciculatum, G. mosseae, G. intraradices) on various growth parameters such as biomass, macro and micronutrients, chlorophyll, protein, cytokinin and alkaloid content and phosphatase activity of pink flowered Catharanthus roseus plants showed that all Glomus species except G. intraradices enhanced the chlorophyll, protein, crude alkaloid, phosphorus, sulphur, manganese and copper contents of C. roseus plants along with phosphatase activity significantly over uninoculated plants. However only G. mosseae and G. fasciculatum exhibited superior symbiotic relationship with the plant. G. mosseae was found to be the best for increasing the crude alkaloid content (8.19%) in leaf and also in increasing the quantity of important alkaloids vincristine and vinblastine.  相似文献   

6.
Four amino acids were variable between the ‘active’ indica-type and ‘inactive’ japonica-type soluble starch synthase IIa (SSIIa) of rice plants; Glu-88 and Gly-604 in SSIIa of indica-cultivars IR36 and Kasalath were replaced by Asp-88 and Ser-604, respectively, in both japonica cultivars Nipponbare and Kinmaze SSIIa, whereas Val-737 and Leu-781 in indica SSIIa were replaced by Met-737 in cv. Nipponbare and Phe-781 in cv. Kinmaze SSIIa, respectively. The SSIIa gene fragments shuffling experiments revealed that Val-737 and Leu-781 are essential not only for the optimal SSIIa activity, but also for the capacity to synthesize indica-type amylopectin. Surprisingly, however, a combination of Phe-781 and Gly-604 could restore about 44% of the SSIIa activity provided that Val-737 was conserved. The introduction of the ‘active’ indica-type SSIIa gene enabled the japonica-type cv. Kinmaze to synthesize indica-type amylopectin. The starch in the transformed japonica rice plants exhibited gelatinization-resistant properties that are characteristic of indica-rice starch. Transformed lines expressing different levels of the IR36 SSIIa protein produced a variety of starches with amylopectin chain-length distribution patterns that correlated well with their onset temperatures of gelatinization. The present study confirmed that the SSIIa activity determines the type of amylopectin structure of rice starch to be either the typical indica-type or japonica-type, by playing a specific role in the synthesis of the long B1 chains by elongating short A and B1 chains, notwithstanding the presence of functional two additional SSII genes, a single SSI gene, two SSIII genes, and two SSIV genes in rice plants.  相似文献   

7.
Chhana based milk products viz. rossogolla, kanchagolla, narampak sandesh and karapak sandesh are very popular in eastern part of India and gaining popularity in other parts of the country. A wide variation in manufacture method, microbial quality and shelf-life of these traditional milk products were observed by previous research. The aim of the present study was to determine the prevalence of contamination of chhana based milk products available in Kolkata city with Enteropathogenic Escherichia coli (EPEC) serogroups. Random samples of different chhana based milk products were collected from different parts of Kolkata city in aseptic condition, cultured in selective media and examined for biochemical tests. Among 240 samples, E. coli was isolated from 67 (27.91%) of them. Potential EPEC was present in 52 samples (21.66%) and 55 of the isolates were EPEC. Eleven serogroups were identified viz. O26, O55, O111, O119, O114, O125, O142, O86, O126, O127, O128. Among all these serogroups, O55 (23.66%) was the most prevalent. Though recent studies on virulence factors indicate that not all strains serologically classified as EPEC are able to attaching/effacing lesion, it is believed that the isolation of EPEC serogroups from chhana based milk products represent a potential risk for public health particularly children, as well as an indicative of the presence of other enteropathogens. Considering the public health importance of sweetmeat consumers, the product should be prepared hygienically reducing the microbial load present in it. The result indicates that strict preventive measures should be adopted to ensure contamination free sweetmeats for the safety of the consumers.  相似文献   

8.
A Sebacinales species was recovered from a clone library made from a pooled rhizosphere sample of Nicotiana attenuata plants from 14 native populations. Axenic cultures of the related species, Piriformospora indica and Sebacina vermifera, were used to examine their effects on plant performance. Inoculation of N. attenuata seeds with either fungus species stimulated seed germination and increased growth and stalk elongation. S. vermifera inoculated plants flowered earlier, produced more flowers and matured more seed capsules than did non-inoculated plants. Jasmonate treatment during rosette-stage growth, which slows growth and elicits herbivore resistance traits, erased differences in vegetative, but not reproductive performance resulting from S. vermifera inoculation. Total nitrogen and phosphorous contents did not differ between inoculated and control plants, suggesting that the performance benefits of fungal inoculation did not result from improvements in nutritional status. Since the expression of trypsin proteinase inhibitors (TPI), defensive proteins which confer resistance to attack from Manduca sexta larvae, incur significant growth and fitness costs for the plant, we examined the effect of S. vermifera inoculation on herbivore resistance and TPI activity. After 10 days of feeding on S. vermifera-inoculated plants, larval mass was 46% higher and TPI activity was 48% lower than that on non-inoculated plants. These results suggest that Sebacina spp. may interfere with defense signaling and allow plants to increase growth rates at the expense of herbivore resistance mediated by TPIs.  相似文献   

9.
Xanthan is a important biopolymer for commercial purpose and it is produced in two stages by Xanthomonas campestris. In the first one, the bacterium is cultivated in the complex medium enriched in nitrogen and the biomass produced is used as inoculum for the next stage in which the gum is produced in another medium. In this work a new medium for the first stage is proposed in place of currently used YM medium. Different formulated growth media were studied and the correspondent biomass produced was analysed as inoculum for the second stage. The inoculum and gum were produced by batch process in shaker at 27°C in pH 6.0 and at 30°C in pH 7.0, respectively. The gum was precipitated with ethanol (3:1 v/v). The dryed biomass and xathan gum produced were determined by drying in oven at 105 and 40°C, respectively. The viscosity of the fermentation broth and 1% gum solution in water were determined in Brookfield viscometer. The formulated medium presented the increase in gum production (30%), broth (136%) and 1% gum solution viscosity (60%) compared to YM, besides the inferior cost. The results showed the importance of the quality of the inoculum from the first stage of the culture which influenced on the gum viscosity in the second stage.  相似文献   

10.
Extracellular hydrolytic enzymes such as amylases, proteases, lipases and DNases have quite diverse potential usages in different areas such as food industry, biomedical sciences and chemical industries, also it would be of great importance to have available enzymes showing optimal activities at different values of salt concentrations and temperature. Halophiles are the most likely source of such enzymes, because not only their enzymes are salt-tolerant, but many are also thermotolerant. The purpose of this study was isolation of hydrolytic extracellular enzyme producing halophilic bacteria from water and sediment of the Persian Gulf. Isolated bacteria from water and sediment were inoculated in media with concentration of 0–20% NaCl to determine the optimum salt concentration for growth, isolates were also inoculated in 4 types of solid medium containing substrates of 3 extracellular hydrolytic enzymes including amylase, Protease and Lipase, to determine the quantitative detection of enzyme production, selected strains after more accurate physiological and biochemical studies were identified regarding phylogeny and molecular characteristics using 16S rRNA technique. Isolated enzyme producing bacteria belong to Pseudoalteromonas genera.  相似文献   

11.
Two plant growth promoting rhizobacteria––Sinorhizobium meliloti RMP1 and Pseudomonas aeruginosa GRC2 were studied for integrated nutrient management to obtain improved yield of Brassica juncea. Low concentrations of urea and diammonium phosphate (DAP) stimulated the growth of both S. meliloti RMP1 and P. aeruginosa GRC2. 1 M of urea and 0.35 M of DAP was found lethal for RMP1, while 1.3 M and 0.37 M concentrations of urea and DAP proved to be toxic for GRC2. Lc50 was observed as 0.49 M of urea and 0.15 M of DAP for RMP1, and 0.66 M urea and 0.18 M of DAP for GRC2. Urea and DAP adaptive variants of RMP1 and GRC2 was isolated. Adaptive bacterial variants had better growth rates at sub-lethal (Lc50) concentrations of urea and DAP as compared to non-adaptive variants. They also retained plant growth promoting attributes similar to non adaptive variants. GRC2 and RMP1 did not affect the growth of each other and were chemotactically active for DAP, urea as well as root exudates of B. juncea. Both the isolates colonized well in the rhizosphere of B. juncea, as their populations were recorded ≈5 log10 cfu g−1 after 120 days. Interestingly, the colonization ability was found even better when both strains were co-inoculated, as their population was recorded in the range of ≈6 log10 cfu g−1 after 120 days. In field trials, application of RMP1 and GRC2 resulted in significant increase in biomass and yield of B. juncea as compared to control. However, yield was better with application of half dose and full dose of recommended fertilizers. Interestingly, the biomass as well as yield improved further when both isolates were applied together along with half dose of recommended fertilizers.  相似文献   

12.
In this study, an incidence pattern of 1.7% for Yersinia enterocolitica and 2.5% for Y. intermedia were observed in an analysis of 120 diversified food samples collected from the local market of Mysore, Southern India. Two native isolates characterized as Y. enterocolitica belonged to biotype 1B and revealed the presence of major virulence related traits such as regulator of virulence, mucoid Yersinia factor regulator, attachment invasion locus, heat stable enterotoxin, Yersinia type II secretory system and phospholipase A in PCR. Force type neighbor-joining phylograms generated for Y. enterocolitica based on PCR amplicons of rovA and ypl showed 100% homology with two to three strains of Y. enterocolitica and about 75% homology with several strains of Y. pestis.  相似文献   

13.
Glycolipid biosurfactant (GLB) from Rhodococcus ruber IEGM 231 was found to stimulate tumor necrosis factor-α (TNF-α), interleukin (IL) -1β and IL-6 production when applied as an ultrasonic emulsion to the adherent human peripheral blood monocyte culture. However, a lack of cytokine-stimulating activity was registered with the GLB applied as a hydrophobic film coating in 24-well culture plates, indicating that it may have been due to its inhibitory effect on monocyte adhesion. The mode of GLB application may therefore play an important role in in vitro assay of immunostimulatory activity of this compound as well as other bacterial glycolipids. Additionally, GLB from R. ruber displayed no cytotoxicity against human lymphocytes and therefore could be proposed as a potential immunomodulating and antitumor agent.  相似文献   

14.
The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.  相似文献   

15.
Endophytic actinomycetes from Azadirachta indica A. Juss. were screened and evaluated for their anti-microbial activity against an array of pathogenic fungi and bacteria. A total of 55 separate isolates were obtained from 20 plants, and 60% of these showed inhibitory activity against one or more pathogenic fungi and bacteria. Actinomycetes were most commonly recovered from roots (54.5% of all isolates), followed by stems (23.6%), and leaves (21.8%). The dominant genus was Streptomyces (49.09% of all isolates), while Streptosporangium (14.5%), Microbispora (10.9%), Streptoverticillium (5.5%), Sacchromonospora sp. (5.5%), and Nocardia (3.6%) were also recovered. Streptomyces isolates AzR 006, 011, and 031 (all from roots) had acute activity against Pseudomonas fluorescens, while AzR027, 032, and 051 (also all from roots) showed activity against Escherichia coli. Meanwhile, an isolate of Nocardia sp. from leaves (AzL025) showed antagonism against Bacillus subtilis. Overall, 32 of the 55 were found to have broad spectrum significant antimicrobial activity, while about 4% of them showed strong and acute inhibition to pathogenic fungi and bacteria. Isolates of Streptomyces AzR031, 008, and 047, Nocardia sp. AzL025, and Streptosporangium sp. AzR 021 and 048 are of particular interest because they showed significant antagonistic activity against root pathogens, including Pythium and Phytophthora sp. Thus, many of the isolates recovered from A. indica in this study may be used in developing potential bio-control agents against a range of pathogenic fungi and bacteria and in the production of novel natural antimicrobial compounds. These results not only further our understanding of plant–microbe interactions but also indicate that there is an untapped resource of endophytic microorganisms that could be exploited in the biotechnological, medicinal, and agricultural industries.  相似文献   

16.
Several food borne outbreaks have highlighted the importance of Listeria monocytogenes to the public health and have been recognized as an emerging, important food borne pathogen, and a causative agent of listerioses. A number of genes are involved in the manifestation of Listeria virulence, hlyA is one among them. In the present study, 111 marine fish samples including prawns, finfishes and bivalves were screened for the presence of Listeria species. The isolates were characterized biochemically and further L. monocytogenes were confirmed by polymerase chain reaction (PCR) technique using the hlyA gene as a tool to differentiate between L. monocytogenes and other non-pathogenic Listeria species. Out of 111 samples 5 (4.5%) samples were positive for L. monocytogenes. Among the three different types of samples bivalves were found to have maximum percent (12.5) of L. monocytogenes followed by prawns (3.84) and finfishes (2.9). Among all the 111 samples, 15 (13.51%) samples were positive for other Listeria species. It was observed that Listeria occurrence is more in shellfishes than in fin fishes. All the isolates were sensitive towards five different antibiotics in sequence ciprofloxacin > sulphafurazole > norfloxacin > ampicillin and gentamicin.  相似文献   

17.
Since the identification of BRI1-Associated receptor Kinase 1 (BAK1), a member of the Somatic Embryogenesis Receptor Kinase (SERK) family, the dual functions of BAK1 in BR signaling and innate immunity in Arabidopsis have attracted considerable attention as clues for understanding developmental processes that must be balanced between growth and defense over the life of plants. Here, we extended our research to study cellular functions of OsSERKs in rice. As it was difficult to identify an authentic ortholog of AtBAK1 in rice, we generated transgenic rice in which the expression of multiple OsSERK genes, including OsBAK1, was reduced by OsBAK1 RNA interference. Resulting transgenic rice showed reduced levels of Os-BAK1 and decreased sensitivity to BL, leading to semidwarfism in overall growth. Moreover, they resulted in abnormal growth patterns, especially in leaf development. Most of the OsBAK1RNAi transgenic rice plants were defective in the development of bulliform cells in the leaf epidermal layer. They also showed increased expression level of pathogenesis-related gene and enhanced susceptibility to a rice blast-causing fungal pathogen, Magnaporthe oryzae. These results indicate that OsSERK genes, such as OsBAK1, play versatile roles in rice growth and development.  相似文献   

18.
Pseudomonas syringae pv. tabaci causes wildfire disease in tobacco plants. The hrp pathogenicity island (hrp PAI) of P. syringae pv. tabaci encodes a type III secretion system (TTSS) and its regulatory system, which are required for pathogenesis in plants. Three important regulatory proteins-HrpR, HrpS, and HrpL-have been identified to activate hrp PAI gene expression. The bacterial Lon protease regulates the expression of various genes. To investigate the regulatory mechanism of the Lon protease in P. syringae pv. tabaci 11528, we cloned the lon gene, and then a Δlon mutant was generated by allelic exchange. lon mutants showed increased UV sensitivity, which is a typical feature of such mutants. The Δlon mutant produced higher levels of tabtoxin than the wild-type. The lacZ gene was fused with hrpA promoter and activity of β-galactosidase was measured in hrp-repressing and hrp-inducing media. The Lon protease functioned as a negative regulator of hrp PAI under hrp-repressing conditions. We found that strains with lon disruption elicited the host defense system more rapidly and strongly than the wild-type strain, suggesting that the Lon protease is essential for systemic pathogenesis.  相似文献   

19.
20.
Summary A protocol has been developed for high-frequency shoot regeneration and plant establishment of Tylophora indica from petiole-derived callus. Optimal callus was developed from petiole explants on Murashige and Skoog basal medium supplemented with 10μM2,4-dichlorophenoxyacetic acid +2,5μM thidiazuron (TDZ). Adventitious shoot induction was achieved from the surface of the callus after transferring onto shoot induction medium. The highest rate (90%) of shoot multiplication was achieved on MS medium containing 2.5μM TDZ. Individual elongated shoots were rooted best on halfstrength MS medium containing 0.5μM indole-3-butyric acid (IBA). When the basal cut ends of the in vitro-regenerated shoots were dipped in 150μM IBA for 30 min followed by transplantation in plastic pots containing sterile vermiculite, a mean of 4.1 roots per shoot developed. The in vitro-raised plantlets with well-developed shoot and roots were successfully established in earthen pots containing garden soil and grown in a greenhouse with 100% survival. Four months after transfer to pots, the performance of in vitro-propagated plants of T. indica was evaluated on the basis of selected physiological parameters and compared with ex vitro plants of the same age.  相似文献   

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