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Item Enhanced Rice Growth is Conferred by Increased Leaf ADP-Glucose Pyrophosphorylase Activity(2014-10) Schlosser, Alanna J.; Martin, John M.; Beecher, Brian S.; Giroux, Michael J.Modification of leaf starch levels may be employed in attempts to increase cereal yield. Few studies have examined leaf starch as a plant biomass limiting factor. Here we test the hypothesis that rice plant productivity may be increased by increasing leaf starch. Starch biosynthesis is controlled by the heterotetrameric rate-limiting enzyme ADP-glucose pyrophosphorylase (AGPase). Rice variety Nipponbare was transformed with a modified form of the maize endosperm AGPase large subunit gene, Sh2r6hs, as well as with the small subunit gene, Bt2, under control of a rice RuBisCO small subunit promoter. RNA sequencing results indicated that Sh2r6hs and Bt2 transcript levels were each greater than 20 times that of the native genes. Increased total AGPase activity was correlated with higher leaf starch accumulation at the end of the day. Yield trials of T1 derived homozygous plants indicate that increased leaf AGPase leads to a 29% increase in plant biomass under the conditions tested without changing the rate of photosynthesis while significantly reducing leaf transpiration and conductance. Additionally, functional annotation clustering of significantly up and down regulated transcripts reveals areas of protein metabolism, specifically protein biosynthesis, transport, and localization, that were altered in response to increased leaf starch. Together, these findings indicate plant growth is limited by native levels of leaf starch and that it is possible to increase plant yield via the starch biosynthesis pathway.Item Bromus tectorum Response to Fire Varies with Climate Conditions(2014-09) Taylor, Kimberley T.; Brummer, Tyler J.; Rew, Lisa J.; Maxwell, Bruce D.The invasive annual grass Bromus tectorum (cheatgrass) forms a positive feedback with fire in some areas of western North America’s sagebrush biome by increasing fire frequency and size, which then increases B. tectorum abundance post-fire and dramatically alters ecosystem structure and processes. However, this positive response to fire is not consistent across the sagebrush steppe. Here, we ask whether different climate conditions across the sagebrush biome can explain B. tectorum’s variable response to fire. We found that climate variables differed significantly between 18 sites where B. tectorum does and does not respond positively to fire. A positive response was most likely in areas with higher annual temperatures and lower summer precipitation. We then chose a climatically intermediate site, with intact sage-brush vegetation, to evaluate whether a positive feedback had formed between B. tectorum and fire. A chronosequence of recent fires (1–15 years) at the site created a natural replicated experiment to assess abundance of B. tectorum and native plants. B. tectorum cover did not differ between burned and unburned plots but native grass cover was higher in recently burned plots. Therefore, we found no evidence for a positive feedback between B. tectorum and fire at the study site. Our results suggest that formation of a positive B. tectorum-fire feedback depends on climate; however, other drivers such as disturbance and native plant cover are likely to further influence local responses of B. tectorum. The dependence of B. tectorum’s response to fire on climate suggests that climate change may expand B. tectorum’s role as a transformative invasive species within the sage-brush biome.Item (6 S *)-6-[(1 S *,2 R *)-1,2-Dihydroxypentyl]-4-methoxy-5,6-dihydro-2 H -pyran-2-one(2013-10) Valenti, Domenic J.; Arif, Atta M.; Strobel, Gary A.; Harper, James K.The title compound, C11H18O5, was isolated from a liquid culture of Pestalotiopsis sp. In the molecule, the pyran-2-one ring assumes a half-chair conformation. The two terminal C atoms of the pentyl group were refined as disordered over two sets of sites, with refined occupancies of 0.881 (10) and 0.119 (10). In the crystal, molecules are linked via O-H...O hydrogen bonds forming a three-dimensional network.Item Evaluation of cellulose as a substrate for hydrocarbon fuel production by Ascocoryne sarcoides (NRRL 50072)(2014-02) Mallette, Natasha D.; Pankrantz, E. M.; Busse, S.; Strobel, Gary A.; Carlson, Ross P.; Peyton, Brent M.The fungal endophyte, Ascocoryne sarcoides, produced aviation, gasoline and diesel-relevant hydrocarbons when grown on multiple substrates including cellulose as the sole carbon source. Substrate, growth stage, culturing pH, temperature and medium composition were statistically significant factors for the type and quantity of hydrocarbons produced. Gasoline range (C5-C12), aviation range (C8-C16) and diesel range (C9-C36) organics were detected in all cultured media. Numerous non-oxygenated hydrocarbons were produced such as isopentane, 3,3-dimethyl hexane and d-limonene during exponential growth phase. Growth on cellulose at 23˚C and pH 5.8 produced the highest overall yield of fuel range organics (105 mg * g·biomass−1). A change in metabolism was seen in late stationary phase from catabolism of cellulose to potential oxidation of hydrocarbons resulting in the production of more oxygenated compounds with longer carbon chain length and fewer fuel-related compounds. The results outline rational strategies for controlling the composition of the fuel-like compounds by changing culturing parameters.