Effect of spraying nitrogen-fixing phyllospheric bacterial isolates on wheat plants
TL;DR: Culture of two nitrogen-fixing bacteria isolated from rice and jute phyllospheres respectively were sprayed on wheat plants as substitute for nitrogenous fertilisers and there was a marked improvement in yield and growth of the plants.
Abstract: Culture of two nitrogen-fixing bacteria (REN2 and JN1) isolated from rice and jute phyllospheres respectively, were sprayed on wheat plants as substitute for nitrogenous fertilisers. There was a marked improvement in yield and growth of the plants. An average increase in yield by 70% was obtained which was very near to that obtained by fertilizer treatment.
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2,133 citations
TL;DR: This review focuses on the bacterial component of leaf microbial communities, with emphasis on P. syringae—a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte, to illustrate the attractiveness and somewhat unique opportunities provided by leaf ecosystems for addressing fundamental questions of microbial population dynamics and mechanisms of plant-bacterium interactions.
Abstract: The extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. This review focuses on the bacterial component of leaf microbial communities, with emphasis on Pseudomonas syringae—a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte. Among the diversity of bacteria that colonize leaves, none has received wider attention than P. syringae, as it gained notoriety for being the first recombinant organism (Ice− P. syringae) to be deliberately introduced into the environment. We focus on P. syringae to illustrate the attractiveness and somewhat unique opportunities provided by leaf ecosystems for addressing fundamental questions of microbial population dynamics and mechanisms of plant-bacterium interactions. Leaf ecosystems are dynamic and ephemeral. The physical environment surrounding phyllosphere microbes changes continuously with daily cycles in temperature, radiation, relative humidity, wind velocity, and leaf wetness. Slightly longer-term changes occur as weather systems pass. Seasonal climatic changes impose still a longer cycle. The physical and physiological characteristics of leaves change as they expand, mature, and senesce and as host phenology changes. Many of these factors influence the development of populations of P. syringae upon populations of leaves. P. syringae was first studied for its ability to cause disease on plants. However, disease causation is but one aspect of its life strategy. The bacterium can be found in association with healthy leaves, growing and surviving for many generations on the surfaces of leaves as an epiphyte. A number of genes and traits have been identified that contribute to the fitness of P. syringae in the phyllosphere. While still in their infancy, such research efforts demonstrate that the P. syringae-leaf ecosystem is a particularly attractive system with which to bridge the gap between what is known about the molecular biology of genes linked to pathogenicity and the ecology and epidemiology of associated diseases as they occur in natural settings, the field.
877 citations
TL;DR: The major function of the polyester in plants is as a protective barrier against physical, chemical, and biological factors in the environment, including pathogens.
Abstract: Polyesters occur in higher plants as the structural component of the cuticle that covers the aerial parts of plants. This insoluble polymer, called cutin, attached to the epidermal cell walls is composed of interesterified hydroxy and hydroxy epoxy fatty acids. The most common chief monomers are 10, 16-dihydroxy C16 acid, 18-hydroxy-9, 10 epoxy C18 acid, and 9, 10, 18-trihydroxy C18 acid. These monomers are produced in the epidermal cells by ω hydroxylation, in-chain hydroxylation, epoxidation catalyzed by P450-type mixed function oxidase, and epoxide hydration. The monomer acyl groups are transferred to hydroxyl groups in the growing polymer at the extracellular location. The other type of polyester found in the plants is suberin, a polymeric material deposited in the cell walls of a layer or two of cells when a plant needs to erect a barrier as a result of physical or biological stress from the environment, or during development. Suberin is composed of aromatic domains derived from cinnamic acid, and aliphatic polyester domains derived from C16 and C18 cellular fatty acids and their elongation products. The polyesters can be hydrolyzed by pancreatic lipase and cutinase, a polyesterase produced by bacteria and fungi. Catalysis by cutinase involves the active serine catalytic triad. The major function of the polyester in plants is as a protective barrier against physical, chemical, and biological factors in the environment, including pathogens. Transcriptional regulation of cutinase gene in fungal pathogens is being elucidated at a molecular level. The polyesters present in agricultural waste may be used to produce high value polymers, and genetic engineering might be used to produce large quantities of such polymers in plants.
403 citations
TL;DR: Three nitrogen fixing bacteria, particularly the Azotobacter, as a foliar biofertilizer to increase mulberry leaf production resulted in improved leaf quality as indicated by their protein content and their impact on silkworm rearing and cocoon production when treated leaves were subjected to bioassay.
Abstract: A field experiment was conducted for two years (1994-96) to evaluate three nitrogen fixing bacteria (NFBs) namely Azotobacter, Azospirillum and Beijerinckia as foliar biofertilizers on mulberry (Morus spp.). Foliar application of these bacteria in their specific culture media with half of the recommended dose of N as a basal application of chemical fertilizer were compared with the recommended dose of N (300 kg/ha per year in four equal splits) but without biofertilizer. Other controls for comparison were respective culture media with half N. All the NFBs improved leaf yield over their respective controls (specific culture media). The addition of Azotobacter resulted in significantly greater yield than that given by the recommended dose of N. The Beijerinckia treatment resulted in a leaf yield equal to that from the recommended dose of N and Azospirillum reduced leaf yield in comparison to that from the recommended N treatment although the yield from Azospirillum treatment was more than that from the culture medium treatments. A combination of NFBs where Azotobacter was one of the components improved leaf yield over single NFB treatments. NFBs also resulted in improved leaf quality as indicated by their protein content and their impact on silkworm rearing and cocoon production when treated leaves were subjected to bioassay. The use of these NFBs, particularly the Azotobacter, as a foliar biofertilizer to increase mulberry leaf production has not been investigated before.
138 citations
TL;DR: A phyllospheric bacterial culture found to contain a fluorescent pseudomonas which was identified as Pseudomonas putida and a Corynebacterium sp.
Abstract: A phyllospheric bacterial culture, previously reported to partially replace nitrogen fertilizer (B. R. Patti and A. K. Chandra, Plant Soil 61:419-427, 1981) was found to contain a fluorescent pseudomonas which was identified as Pseudomonas putida and a Corynebacterium sp. The P. putida isolate was found to produce an extracellular cutinase when grown in a medium containing cutin, the polyester structural component of plant cuticle. The Corynebacterium sp. grew on nitrogen-free medium but could not produce cutinase under any induction conditions tested, whereas P. putida could not grow on nitrogen-free medium. When cocultured with the nitrogen-fixing Corynebacterium sp., the P. putida isolate grew in a nitrogen-free medium, suggesting that the former provided fixed N2 for the latter. These results suggest that the two species coexist on the plant surface, with one providing carbon and the other providing reduced nitrogen for their growth. The presence of cutin in the medium induced cutinase production by P. putida. However, unlike the previously studied fungal systems, cutin hydrolysate did not induce cutinase. Thin-layer chromatographic analysis of the products released from labeled apple fruit cutin showed that the extracellular enzyme released all classes of cutin monomers. This enzyme also catalyzed hydrolysis of the model ester substrates, p-nitrophenyl esters of fatty acids, and optimal conditions were determined for a spectrophotometric assay with p-nitrophenyl butyrate as the substrate. It did not hydrolyze triacyl glycerols, indicating that the cutinase activity was not due to a nonspecific lipase. It showed a broad pH optimum between 8.0 and 10.5 with 3H-labeled apple cutin as the substrate.(ABSTRACT TRUNCATED AT 250 WORDS)
59 citations
References
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01 Jan 1954
TL;DR: In this article, statistical methods for agricultural workers were used to train agricultural workers in the field of agricultural productivity and agricultural productivity, and the results showed that agricultural workers performed better than other agricultural workers.
Abstract: Statistical methods for agricultural workers , Statistical methods for agricultural workers , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
3,396 citations
161 citations
TL;DR: In the limited space of the petri dish the cultural conditions for active nitrogen fixation quickly deteriorated by the accumulation of metabolic products from both the leaf and the microvegetation, and Heterotrophs and predatory protozoa eventually dominated the initial population.
Abstract: SummaryMeasurements of the amounts of anthrone- and ninhydrin-positive substances occurring in rain-water and dew on plants in Surinam have been made, as well as of the possible nitrogen gains and losses in the dew.Nitrogen fixation in detached leaves in association with an autochthonous phyllosphere population and in those enriched withAzotobacter sp.,Beijerinckia sp., orPseudomonas sp. are compared.Dry weight and total nitrogen increases of single leaves, or part of leaves, of Coffea, Gossypium, and Phaseolus floated on a nitrogen-free medium in petri dishes were determined at intervals of a few days and compared with a control at the start of the experiment.Gains in total nitrogen amounting to 20 to 105 per cent over the control were measured within two weeks. The increases were found in the leaves as well as in the culture medium and were dependent on the age of the leaf, on the light, and on the temperature. The energy substrates for bacterial nitrogen fixation were obviously furnished by the leaf, which increased in size and up to 200 per cent in dry weight.In the limited space of the petri dish the cultural conditions for active nitrogen fixation quickly deteriorated by the accumulation of metabolic products from both the leaf and the microvegetation. Heterotrophs and predatory protozoa eventually dominated the initial population. Earlier gains were then partly lost.The consequences of the biocoenosis of leaves and microbes for the vegetation are discussed.
73 citations
58 citations
TL;DR: It was shown that Azotobacter did not colonize the roots of lucerne, maize, tomato, or wheat to any great extent and Bacillus and Clostridium were moderate colonizers of plant roots reaching from 1 to 20 per cent the levels reached by Pseudomonas fluorescens on the same plants.
Abstract: Seed of maize, tomato, and wheat was inoculated with cultures of Azotobacter, Clostridium, and a nitrogen-fixing facultative Bacillus and grown in a nutrient-deficient sand and a highly fertile silt loam. In sand, wheat showed a significant positive response to inoculation with Azotobacter and Clostridium but maize and tomato were unaffected by inoculation. When inoculated seed was planted in Lima silt loam there were significant increases in the growth of maize, tomato, and wheat to treatment with Clostridium, inoculated maize and wheat responded to Azotobacter inoculation while only wheat responded to inoculation with the facultative Bacillus. In pure-culture studies of the ability of these cultures to establish upon plant roots it was shown that Azotobacter did not colonize the roots of lucerne, maize, tomato, or wheat to any great extent. Bacillus and Clostridium were moderate colonizers of plant roots reaching from 1 to 20 per cent the levels reached byPseudomonas fluorescens on the same plants.
56 citations