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Sequence analysis of the genome of the plant growth-promoting bacterium Pseudomonas putida UW4Duan, Jin January 2012 (has links)
The plant growth-promoting bacterium (PGPB) Pseudomonas putida UW4, previously isolated from the rhizosphere of common reeds growing on the campus of University of Waterloo, promotes plant growth in the presence of different environmental stresses, such as flooding, high concentration of salt, cold, heavy metals, drought and phytopathogens. The known mechanisms used by P. putida UW4 to promote plant growth include 1-aminocyclopropane-1-carboxylate (ACC) deaminase, indole-3-acetic acid (IAA) synthesis and siderophore production. In this work, the genome sequence of UW4 was obtained by pyrosequencing and the gaps between the contigs were closed by directed PCR. The P. putida UW4 genome contains a single circular chromosome that is 6,183,388 bp with a 60.05% G+C content. The bacterial genome contains 5,431 predicted protein-coding sequences that occupy 87.4% of the genome. Nineteen genomic islands were predicted and thirty one complete putative insertion sequences were identified. Genome analyses were conducted in order to better characterize the general features of the UW4 genome. Genes potentially involved in plant growth promotion such as IAA biosynthesis, trehalose production, siderophore production, and acetoin synthesis were identified, which will facilitate a better understanding of the mechanisms of plant-microbe interactions. Moreover, genes that contribute to the environmental fitness of UW4 were also determined including genes responsible for heavy metal resistance such as nickel, copper, cadmium, zinc, molybdate, cobalt, arsenate, and chromate. Central metabolic pathways helped elucidate the physiological roles of diverse metabolites of UW4. Unexpectedly, whole-genome comparison with other completely sequenced Pseudomonas sp. revealed that UW4 is more similar to the fluorescens group rather than to the putida group. More surprisingly, a putative type III secretion system (T3SS) was found in the UW4 genome, and T3SS was thought to be essential for bacterial pathogenesis. Although putative T3SS was observed in other non-pathogenic Pseudomonas spp. previously, this is the first report indicating that a T3SS in a Pseudomonas sp. is highly similar to the one from Salmonella spp.
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Plant Growth-Promoting Bacterial Endophytes that contain ACC Deaminase: Isolation, Characterization, and UseAli, Shimaila January 2013 (has links)
Bacteria that provide benefit to plants are considered to be plant growth-promoting bacteria (PGPB) and can facilitate plant growth by a number of different mechanisms. Plant growth-promoting bacteria that are able to utilize the plant compound 1-aminocyclopropane-1-carboxylate (ACC) as a sole source of nitrogen, as a consequence of possessing the enzyme ACC deaminase, can protect host plants from a number of environmental stresses. In addition to ACC deaminase, PGPB may utilize other mechanisms to facilitate plant growth including IAA synthesis, siderophore production, phosphate solubilization activity, ammonia production, and antibiotic production.
Plant growth-promoting bacterial endophytes employ similar plant growth promotion mechanisms to those used by rhizospheric PGPB. In fact, bacterial endophytes are PGPB that go one step further and colonize the inside of the plant tissues and provide more efficient and prompted protection to their hosts compared to those that bind exclusively to the plant’s rhizosphere. Therefore, it is likely that endophytic plant growth-promoting bacteria will be superior to similar non-endophytic bacterial strains in promoting plant growth under a wide range of environmental conditions.
In the work reported here, new bacterial endophytes were isolated and characterized. Among twenty-five ACC deaminase positive strains, two best strains were selected and ACC deaminase deficient mutants were constructed. The ability of two newly isolated 1-aminocyclopropane-1-carboxylate (ACC) deaminase-containing plant growth-promoting bacterial endophytes Pseudomonas fluorescens YsS6, Pseudomonas migulae 8R6 and their ACC deaminase deficient mutants was shown to 1) delay the senescence of mini carnation cut flowers and 2) to facilitate tomato plant growth under salinity stress.
In the mini carnation flower senescence evaluation, the only difference between wild-type and mutant bacterial endophytes was ACC deaminase activity, our results demonstrate that this enzyme is directly responsible for a significant delay in flower senescence. Despite containing ACC deaminase activity, the rhizosphere-binding PGPB Pseudomonas putida UW4 was not taken up by the cut flowers and therefore had no effect on prolonging flower shelf life.
In evaluating the effect of bacterial endophytes under salt stress, tomato plants treated with either of the wild-type strains of the two selected bacterial endophytes demonstrated early flowering and fruiting and had significantly greater numbers of flowers, buds, and fruits than either the corresponding ACC deaminase mutant strain-treated plants or the control plants. Although both bacterial endophytes P. fluorescens YsS6 and P. migulae 8R6 showed significant plant growth-promotion capabilities, P. migulae 8R6 demonstrated better plant growth facilitation under salt stress than did P. fluorescens YsS6. P. migulae 8R6 treated tomato plants demonstrated the least sodium uptake, the highest chlorophyll content, and highest fresh and dry biomass.
The results of the work presented here suggest that ACC deaminase containing selected bacterial endophytes could be employed as environmentally friendly adjuncts to agricultural and horticultural practice.
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Analysis of indole-3-butyric acid auxin activity in ArabidopsisPoupart, Julie January 2004 (has links)
Auxins are plant hormones involved in virtually all aspects of plant life. Despite long-term commercial and horticultural use of the auxin Indole-3-Butyric Acid (IBA), a full recognition of its natural occurrence in plants was made only recently. I have used multiple approaches to dissect the role of IBA in Arabidopsis thaliana. This thesis includes the first characterization of a mutant with an altered response to IBA that retains wild-type sensitivity to Indole-3-Acetic Acid (IAA), the most studied endogenous auxin. This mutant, named resistant to IBA ( rib1), has modified root architecture and gravitropism and is resistant to auxin transport inhibitors. As these phenotypes are reminiscent of those of characterized auxin transport mutants, movement of IAA and IBA was studied in wild-type and mutant plants. IBA is transported in seedlings in three distinct flows, like IAA, and this transport is saturable, indicating it is carrier mediated. However, unlike IAA, IBA is not polarly transported in inflorescence axes, and IBA transport is not sensitive to IAA transport inhibitors. These results suggest IAA and IBA transport could be mediated or regulated by different mechanisms. In rib1 seedlings, all flows of IBA transport are modified, while IAA transport levels are unchanged. Modifications in IBA transport match phenotypic differences between rib1 and wild-type, and analyses of the physiological effects of IBA also suggest IBA has a role in defining wild-type seedling morphology in Arabidopsis. Though IAA transport levels are not changed in rib1, one flow of IAA transport is rendered insensitive to IAA transport inhibitors, perhaps revealing cross-talk between IAA and IBA transport regulation. Additionally, double mutant analyses reveal that IAA transport and response mutants can suppress some phenotypes of rib1, and some mutant combinations produce novel phenotypes, further suggesting cross-talk between IBA and IAA transport and response p
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Induction of growth promotion and stress tolerance in arabidopsis and tomato by plant growth-promotingHu, Chia-Hui. Kloepper, Joseph. January 2005 (has links) (PDF)
Dissertation (Ph.D.)--Auburn University, 2005. / Abstract. Includes bibliographic references (p.83-96).
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A study of some physiologically active components of alfalfaKapadia, Govind Jethabhai, January 1959 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 152-155).
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Relation between energy supply and cell yield in microorganismsHernandez, Eovaldo, January 1967 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographies.
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Nutritional requirements of a tomato tissue culture growth promoting factors from peas /Witherell, Sanford Stowell, January 1968 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. Includes bibliographical references.
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Growth regulator effects on alfalfa, Medicago sativa L. with simple, trifoliolate and multifoliolate leavesYeh, Kuen-Jann, January 1968 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
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A study of the "malt factor" requirement for the growth of spruce tissue culturesStandifer, Leonidas Calmet, January 1959 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 81-85).
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Nitrogen form uptake capacities by arbuscular mycorrhizae and ectomycorrhizaeUbhi, Ramnique 30 August 2017 (has links)
Plant growth and survival are affected by the nutrients available in the environment. Nitrogen (N) is most often the limiting nutrient in terrestrial ecosystems, particularly in temperate and boreal forests, such as those on Vancouver Island. To overcome the challenge of limited nutrient availability, plants have evolved symbiotic relationships with fungi, called mycorrhizae. While research on the importance of mycorrhizal symbioses for N uptake by plants continues to grow, we have a limited understanding of the mechanisms of N uptake and transfer by mycorrhizae. This knowledge is crucial to fully understand N uptake and assimilation by plants. This study aimed to determine the influence of soil N availability on conifer growth and foliar N content, and on the N form preferences and sporocarp N content of associated mycorrhizae. Inorganic and organic soil N production was determined for two sites, Fairy Lake and San Juan, near Port Renfrew British Columbia, under pure plantations of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco), Sitka spruce (Picea sitchensis [Bong.] Carr.), western redcedar (Thuja plicata Donn ex D. Don in Lamb) and western hemlock (Tsuga heterophylla [Raf.] Sarg.). Ammonium, nitrate and amino acid production contrasted between the sites, with relatively higher N production in San Juan compared to Fairy Lake. This indicated differences in soil N cycling, most likely due to differences in moisture and topography. In general, conifer species did not affect inorganic and organic soil N production. Growth of conifers increased with increasing N availability, and differed between species, with Douglas-fir and Sitka spruce having the greatest growth and western redcedar having the least growth. Foliar %N and 15N were found to differ among the conifer species, and western redcedar had the lowest foliar N concentrations. While site quality was not reflected in foliar %N, foliar 15N was found to increase with increasing 15N of the forest floor. Ectomycorrhizal (ECM) sporocarps reflected site quality, with greater N concentrations but lower 15N values on the higher N site. Sporocarp 15N concentrations were higher than foliar 15N concentrations, suggesting N isotope fractionation by mycorrhizae. Finally, site N availability was not related to the rates of N form uptake by ECM genera. Both ECM and arbuscular mycorrhizae (AM) did not have substantial nitrate uptake, despite a greater supply of nitrate. Ammonium was found to be taken up at higher rates than nitrate in the ECM and AM roots, suggesting a preference for ammonium, possibly due to ammonium being energetically cheaper to metabolize and suppressing nitrate transporters in mycorrhizal fungi. Differences in proportions of N form uptake and sporocarp N content among ECM genera were seen, indicating potential niche formation based on functional traits such as N form uptake and mycelial morphology. Knowing how mycorrhizae respond to different N forms and rates of N supply will not only increase our knowledge of N dynamics in mycorrhizal symbioses, but will help predict the effects environmental changes, such as disturbance and N deposition, may have on these systems. / Graduate / 2018-08-09
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