Browsing by Subject "Abscisic acid (ABA)"
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Item Abscisic acid concentration of zoysiagrass seed during maturation and its relationship to germination(Texas Tech University, 2000-05) Myrick, Matthew DZoysiagrass has been propagated primarily by vegetative means. Prior research has indicated that for Zoysiagrass to provide an established lawn from seed it has to be scarified chemically and/or mechanically, and even then success is very low. Results from the objectives of this study show that the glume is a physical barrier contributing to the inhibition of germination and/or the promotion of dormancy by reducing permeability to environmental elements. Toward the end of seed development, potential for germination is also reduced due to increased hardness of the seed coat. Although physical barriers do significantly contribute to dormancy of seed, they are not the key factor to consider. Germination and dormancy are also affected by concentrations of hormones, embryo maturity, and the surrounding environment. Abscisic acid (ABA), a plant hormone, was chosen for evaluation due to prior research indications for its involvement in promoting dormancy. However, what has been shown here is that ABA does not have a significant involvement in the inhibition or reduction of germination of zoysiagrass seed. It also indicates that ABA is not significantly involved in the induction of seed dormancy. Therefore, the germination and establishment potential of Zoysiagrass, from seed, may be improved through further evaluation of other endogenous hormones and/or Genetic manipulation.Item Functional analysis of select Arabidopsis ABA INSENSITIVE1/2-Like protein phosphatases(2008-05) Zhang, Tiantian; Chris, RockWe have utilized a maize protoplast transient gene expression system to investigate the possible roles of several Arabidopsis protein phosphatase type 2C (PP2Cs), which are predicted to be involved in ABA responses by hierarchical clustering meta-analysis of transcriptome profiling datasets and sequence homologies to known PP2C effector ABA INSENSITIVE1. We recombined Cre-lox UPS host acceptor vectors (pCR701-705) containing the maize Ubiquitin promoter and N-terminal epitope tags with pUNI donor vectors containing various full length Arabidopsis PP2C cDNAs. On the basis of my maize protoplast transient expression data that suggested ABA antagonist effects of several overexpressed PP2Cs, I performed a reverse-genetic screen for AP2C9, AP2C12 and AP2C15 T-DNA insertion mutants and found supportive evidence from physiological assays on seed germination and root growth that these PP2Cs may be involved in ABA signaling. I conclude that the utilization of the maize protoplast transient expression system for moderate-throughput functional screening and systems-approach classification of gene activities can contribute to elucidation of plant abscisic acid (ABA) signal transduction pathways when combined with complimentary genetic and physiological approaches.