<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>
| Identifer | oai:union.ndltd.org:PROQUEST/oai:pqdtoai.proquest.com:1523069 |
| Date | 09 August 2013 |
| Creators | Puhr, RoseMary Allyson |
| Publisher | California State University, Long Beach |
| Source Sets | ProQuest.com |
| Language | English |
| Detected Language | English |
| Type | thesis |
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