Browsing by Subject "silica bodies"

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    Investigations of low input turfgrasses
    (2017-01) Dabney, Clemon
    The development of low-input turfgrasses has been challenging for plant breeders. Turfgrasses typically lack resources for crop improvement that are common in other crops, such as a fully sequenced genome. New tools are needed to study turfgrass and decrease its environmental impact. Two approaches were developed and utilized in this project: investigating the rhizosphere associated with low-input turfgrasses and quantifying silica body deposition in various turfgrass species. Understanding how microorganisms associate with different species and cultivars of turfgrass may in the future provide researchers the ability to breed for turfgrass plants that form better mutualistic and beneficial relationships with soil microorganisms. In some plants, plant genotype seems to have a significant influence on shaping the microbial community structures. Previous research in Poaceae has shown that a plant genotype has the ability to influence the rhizosphere microbial community structure. The objectives of this study were to (1) determine if turfgrass species affects soil microbial community structure and (2) identify differences in soil microbial community structure of turfgrasses based on nitrogen fertility regime. Rhizosphere and rhizoplane soil samples were taken from six species of turfgrass, prairie junegrass (Koeleria macrantha (Ledeb.) Schult.), Kentucky bluegrass (Poa pratensis L.), hard fescue (Festuca trachyphylla (Hackel) Krajina), colonial bentgrass (Agrostis capillaris L.), as well as tufted hairgrass (Deschampsia caespitosa (L.) P. Beauv.) and DNA isolated from each sample was then amplicons were pair end sequenced using Illumina HiSeq 2000 at a read length of 2 x 150 base pairs. Data was analyzed using WinSCP, Putty and Mothur. Our results show that the rhizosphere community structure is influenced by location, fertility, and genotype. iii We also found that Thermodesulfobacteria and Thaumarchaeota are associated with fertilized turfgrass soils. Weed incidence, a measure of turf performance, was found to associate to the Actinobacteria, Verrumicrobia, and Bacteroidetes. Results from this research will inform turfgrass researchers about the impacts of turfgrass species and nitrogen fertility on soil microbial communities. The deposition of silicon into epidermic cells of grass species is thought to be an important mechanism that plants use to defend against pests and environmental stresses. Turfgrass cultivars within the same species exhibit different tolerances under traffic stress and some of these differences may be attributed to silica bodies. There are a number of techniques available to study the size, density and distribution pattern of silica bodies in grass leaves. None of those techniques, however, can provide a high-throughput and accurate analysis, especially for a great number of samples. The purpose of this study was to develop a high-throughput method that uses the fluorescence-emitting nature of silica bodies along with fluorescence microscopy and image software to investigate the size, density, and distribution patterns of these bodies in the perennial grass Koeleria macrantha. Dry ashing, followed by fluorescent microscopy, was utilized to image silica bodies in prairie junegrass. ImageJ was used to analyze the images for size, number and orientation. We found that dry-ashing and fluorescent microscopy can be combined with ImageJ to create a high throughput method to study silica bodies in turfgrass. Our results indicated that abaxial and adaxial deposition in turfgrasses are significantly different and that turfgrass genotypes showed significant differences in number of carbon inclusions and silica body deposition.