Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2007. / Title from PDF t.p. (viewed Nov. 20, 2008). Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1414. Adviser: Loren H. Rieseberg.

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2008. / Title from home page (viewed on Oct 30, 2009). Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4538. Adviser: Loren H. Rieseberg.

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2005. / Title from PDF t.p. (viewed Dec. 2, 2008). Source: Dissertation Abstracts International, Volume: 66-02, Section: B, page: 0651. Chair: Jeffrey Palmer.

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2005. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0033. Adviser: Lynda F. Delph. "Title from dissertation home page (viewed Feb. 9, 2007)."

Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2005. / Source: Dissertation Abstracts International, Volume: 66-08, Section: B, page: 4033. Adviser: Lynda F. Delph. Title from dissertation home page (viewed Oct. 10, 2006).

<p> The redistribution of nitrogen from old leaves to young leaves during senescence is crucial for plant survival. The <i>Arabidopsis thaliana </i> chloroplast residential protease S33Ab (At5g11650) was predicted to contribute to the degradation of chloroplast stromal proteins during senescence by bioinformatics tools. Rubisco degradation did not co-segregate with the T-DNA insertion mutant <i>s33Ab.</i> The location of T-DNA insertions into <i>S33Ac</i> (At1g18360) and <i>S33Ad</i> (At1g73480) were confirmed by sequencing. Total leaf proteins from <i>Ab, Ac, Ad </i> single, <i>Ab/Ac, Ab/Ad, Ac/Ad</i> double and <i> Ab/Ac/Ad</i> triple mutants were isolated from senescing leaves, subjected to immunoblot analysis to quantify Rubisco large subunit (LSU), glutamine synthase 2 (GS2), Rubisco activase (RCA), and light harvesting complex protein for photosystem II, b (Lhcb1) and compared to wild type. There is no significant difference among all the genotypes. This genetic analysis shows that S33Ab and its two closely related homologs, S33Ac and S33Ad do not individually contribute or work additively in chloroplast stromal protein degradation.</p>

<p> Auxin is a phytohormone that has long been known to control many aspects of plant growth and development. The YUCCA (YUC) gene family is a large group of genes that catalyze auxin biosynthesis and have been shown to be critical for vegetative growth and inflorescence development in grasses. There is genetic redundancy present with <i>Arabidopsis YUCs,</i> but in <i> Zea mays</i> (maize), a single gene knockout of <i>ZmSPI1</i> causes a severe inflorescence phenotype. Since <i>Oryza sativa</i> (rice), another grass species, does not show an inflorescence phenotype when <i> OsYUC1/SPI1</i> is knocked down, <i>SPI1</i> appears to have undergone an evolutionary shift in function within the grass family. This study shows that <i>SPI1</i> expression in PACMAD (Panicoideae, Arundinoideae, Chlorodoideae, Micrairoideae, Aristidoideae, and Danthoniodeae subfamilies) clade grasses <i>Sorghum bicolor</i> and <i>Setaria italica</i> occurs at sites of inflorescence branching and is consistent with maize, but in BEP (Bambusoideae, Ehrhartoideae, and Pooideae subfamilies) clade grasses rice and <i>Brachypodium distachyon SPI1</i> shifts from localized expression to more generalized expression and potentially becomes weaker. Artificial microRNA (amiRNA) knockdowns of <i>SPI1 </i> expression in <i>Brachypodium</i> did not show a phenotype when expression was reduced to 28.01% (+/- 6.39%) of wild type. In rice and <i> Brachypodium,</i> other <i>YUC</i> genes were shown to be expressed in the inflorescence by quantitative RT-PCR (qPCR), suggesting YUC proteins are more redundant in BEP grasses such as <i>B. distachyon</i> and <i> O. sativa,</i> than in maize and potentially its relatives.</p>

No description available.

<p>Much of plant growth is directly or indirectly regulated by the plant hormone auxin. Although some genes involved in the auxin pathway have been characterized, there are still gaps in our knowledge of this genetic pathway. Recently, the orthologous maize genes <i>BARREN STALK2</i> (<i> BA2</i>) and rice gene <i>LAX PANICLE2</i> (<i>LAX2</i>) have been cloned and characterized. Maize <i>ba2</i> and rice <i> lax2</i> mutant plants both show significant flaws in axillary meristem (AM) initiation, suggesting a role in auxin regulation. In support of this hypothesis, <i>LAX2</i> interacts with the auxin regulating <i> LAX PANICLE1</i> (<i>LAX1</i>) protein. My research reconstructs the evolutionary history of the <i>BA2</i>/<i>LAX2</i> lineage and tests for conservation of <i>BA2</i>/<i>LAX2</i> mRNA expression in diverse grasses. My results indicate that the <i> BA2</i>/<i>LAX2</i> gene family&mdash;comprising <i>BA2 </i>/<i>LAX2</i>, <i>BA2</i>/<i>LAX2-Like1</i> (<i>BA2</i>/<i>LAX2L1</i>), and <i>BA2</i>/<i> LAX2-Like2</i> (<i>BA2</i>/<i>LAX2L2</i>)&mdash;is restricted to monocots, and shows evidence of two independent gene duplication events. During its evolution, the <i>BA2</i>/<i>LAX2</i> gene family appears to have gained a PDZ Protein Binding motif, which may allow it to interact with other proteins besides <i>BA1</i>/<i> LAX1</i>. My expression analyses show that <i>BA2</i>/<i> LAX2</i> genes are expressed during multiple stages of inflorescence development, and this expression is conserved across multiple grass species. A unique floral expression pattern appears to have evolved at the base of the Joinvilleaceae lineage. My study further supports the hypothesis that <i> BA2</i>/<i>LAX2</i> genes are functioning in multiple AM pathways. </p>

Thesis (Ph.D.)--North Carolina State University, 2006. / (UnM)AAI3223123. Advisers: Ronald Sederoff; Thomas Wentworth. Source: Dissertation Abstracts International, Volume: 67-06, Section: B, page: 2912.