Plants reduce inorganic carbon to synthesize biomass that is comprised of mostly polysaccharides and lignin. Growth is intricately regulated by external cues such as light, temperature, and water availability and internal cues including those generated by the circadian clock. While many aspects of polymer biosynthesis are known, their regulation and distribution within the stem are poorly understood. Plant biomass is perhaps the most abundant organic substance on Earth and can be used as feedstock for energy production. Various grass species are under development as energy crops yet several of their attributes make them challenging research subjects. Brachypodium distachyon has emerged as a grass model for food and energy crop research. I studied rhythmic growth, a phenomenon important to understanding how plant biomass accumulates through time, and vascular system development, which has biofuel feedstock conversion efficiency and yield. Growth rate changes within the course of a day in a sinusoidal fashion with a period of approximately 24 hours, a phenomenon known as rhythmic growth. Light and temperature cycles, and the circadian clock determine growth rate and the timing of rate changes. I examined the influences of these factors on growth patterns in B. distachyon using time-lapse photography. Temperature and, to a lesser extent, light influenced growth rate while the circadian clock had no noticeable effect. The vascular system transports important materials throughout the plant and consists of phloem, which conducts photosynthates, and xylem, which conducts water and nutrients. The cell walls of xylem elements and ground tissue sclerenchyma fibers are comprised of cellulose, hemicelluloses, and lignin. These components are important to alternative energy research since cellulose and hemicellulose can be converted to liquid fuel, but lignin is a significant inhibitor of this process. I investigated vascular development of B. distachyon by applying various histological stains to stems from three key developmental. My results described in detail internal stem anatomy and demonstrated that lignification continues after crystalline cellulose deposition ceases. A better understanding of growth cues and various anatomical and cell wall construction features of B. distachyon will further our understanding of plant biomass accumulation processes.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:theses-2028 |
| Date | 01 January 2012 |
| Creators | Matos, Dominick A |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Masters Theses 1911 - February 2014 |
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