Abstract: Radical coupling reactions between ethyl ferulate (Et-FA), a simple model for feruloyl polysaccharides in planta, and coniferyl alcohol (CA), a monolignol, were studied in order to better understand the polymer cross-coupling interactions among polysaccharides and monolignols or lignin, mediated by ferulate (FA), in plant cell walls. Cross-coupled FA/CA dimers produced in an aqueous buVer (pH 5.0) containing peroxidase/hydrogen peroxide were isolated and characterized by NMR. The total coupling products were characterized by 2D 13C–1H correlation (HSQC) NMR spectroscopy and GC–MS. Results from this study showed that ferulate readily cross-couples with coniferyl alcohol through free radical coupling mechanisms producing a series of cross-coupled FA/CA dimers with β-O-4-, β-5-/8-5-, and 8-β-linkages; the syntheses and isolation of β-5- and 8-5-cross-coupled dimers are reported here. The transformation from 8-β-coupled FA/CA hydroxyl esters into lactones through intramolecular transesterification is demonstrated for the Wrst time and mechanisms behind these transformations are discussed. The Wnding of both β-5- and 8-5-cross-coupled dimers in this study suggests that analogs of both may be present in plant cell walls. Finally it is suggested that ferulates in plants indeed react with monolignols through free radical mechanisms producing a more diverse array of cross-coupled dimers than previously reported.

Abstract: Poplar lignins with exceedingly high syringyl monomer levels are produced by over-expression of the ferulate 5-hydroxlase (F5H) gene driven by a cinnamate 4-hydroxylase (C4H) promoter. Compositional data derived from both standard degradative methods and NMR analyses of the entire lignin component (as well as isolated lignin fraction) indicated that the C4H::F5H transgenic lignin was comprised of as much as 97.5% syringyl units (derived from sinapyl alcohol), the remainder being guaiacyl units (derived from coniferyl alcohol); the syringyl level in the wild-type control was 68%. The resultant transgenic lignins are more linear, and display a lower degree of polymerization. Although the crucial β-ether content is similar, the distribution of other inter-unit linkages in the lignin polymer is markedly different, with higher resinol (β–β) and spirodienone (β–1) contents, but with virtually no phenylcoumarans (β–5, which can only be formed from guaiacyl units). p-Hydroxybenzoates, acylating the γ-positions of lignin sidechains, were reduced by over 50%, suggesting consequent impacts on related pathways. A model depicting the putative structure of the transgenic lignin resulting from the over-expression of F5H is presented. The altered structural features in the transgenic lignin polymer, as revealed here, support the contention that there are
significant opportunities to improve biomass utilization by exploiting the malleability of plant lignification processes.

Abstract
The amino sugars (e.g.,glucosamine, galactosamine, mannosamine, muramicacid) in soils are frequently employed as biomarkers of microbial residues. The analysis of amino sugars in environmental matrices, however, is expected to be more complicated than their determination in isolated microbial cells. In this study, we employed a widely used protocol for amino sugar analysis, and found that some amino glycoside antibiotics interfere with amino sugar quantification invitro. The method converts the amino glycosides to compounds that coelute with the aldononitrile acetate derivatives of the amino sugars. Specifically, streptomycin significantly interferes with muramicacid analysis, and kanamycin, tobramycin and amikacin hamper glucosamine measurement. Mass spectrometry confirmed that the interfering compounds from aminoglycosides are not actually genuine microbial amino sugar monomers (bacterial muramic acid or fungal glucosamine), and are most likely to be N-methylglucosamine or 3-amino-3-deoxy-glucopyranose. In contrast to their effects on muramic acid and glucosamine analyses, aminoglycosides do not interfere with galactosamine and mannosamin equantification. The few data that exist on the environmental occurrence of aminoglycoside antibiotics suggest they occur at only trace levels. Our findings may have implications for the qualitative and quantitative validity of results from amino sugar assays in some context. Application of the aldononitrile acetate derivatization method to samples (especially in selective microbial cultures using aminoglycosides as inhibitors) requires that potential interference be evaluated.

Abstract
Genome sequencing and subsequent global gene expression studies have advanced our understanding of the lignocellulose fermenting yeast Pichia stipitis. These studies have given insight into its central carbon metabolism, and analysis of its genome has revealed numerous functional gene clusters and tandem repeats. Specialized physiological traits are often the result of several gene products acting together. When co‐inheritance is necessary for the overall physiological function, recombination and selection favors co‐location of these genes in a cluster. These are particularly evident in strongly conserved and idiomatic traits. In some cases, the functional clusters consist of multiple gene families. Phylogenetic analyses of the members in each family show that once formed, functional clusters undergo duplication and differentiation. Genome‐wide expression analysis reveals that regulatory patterns of clusters are similar after they have duplicated and that the expression profiles evolve along with functional differentiation of the clusters. Orthologous gene families appear to arise through tandem gene duplication followed by differentiation in the regulatory and coding regions of the gene. Genome‐wide expression analysis combined with cross‐species comparisons of functional gene clusters should reveal many more aspects of eukaryotic physiology.

Abstract
This study investigated long-term agronomic management systems and precipitation level effects on soybean [Glycine max (L.) Merr.] total oil content and fatty acid composition. Management systems evaluated included conventional (CT), no-till (NT), low chemical input (LI), and zero chemical input (ORG). Total oil content and major fatty acids profi les were analyzed by accelerated solvent extractor (ASE 200) and gas chromatography with fl ame ionization detector (FID). The results showed these four management systems have limited infl uence on soybean grain total oil content and oleic acid (O) and linoleic acid (L) compositions. The NT management system signifi cantly improved soybean oil yield on a land-area basis as a result of higher annual grain yields. Soybeans grown under the NT management system had as high or higher palmitic acid (P) composition than the other three management systems; similarly, the CT treatments had as low or lower linolenic acid (LN) composition in soybean when compared with the other three management systems. The levels of stearic acid (S), O, L, and LN had a significant quadratic relationship (R2 = 0.64–0.75) with total (July–September) precipitation. The oil quality ratio of O/(L + LN) had a quadratic relation with precipitation.

Abstract: The reactions leading to triacylglycerol (TAG) synthesis in oilseeds have been well characterized. However, quantitative analyses of acyl group and glycerol backbone fluxes that comprise extraplastidic phospholipid and TAG synthesis, including acyl editing and phosphatidylcholine-diacylglycerol interconversion, are lacking. To investigate these fluxes, we rapidly labeled developing soybean (Glycine max) embryos with [14C]acetate and [14C]glycerol. Cultured intact embryos that mimic in planta growth were used. The initial kinetics of newly synthesized acyl chain and glycerol backbone incorporation into phosphatidylcholine (PC), 1,2-sn-diacylglycerol (DAG), and TAG were analyzed along with their initial labeled molecular species and positional distributions. Almost 60% of the newly synthesized fatty acids first enter glycerolipids through PC acyl editing, largely at the sn-2 position. This flux, mostly of oleate, was over three times the flux of nascent [14C]fatty acids incorporated into the sn-1 and sn-2 positions of DAG through glycerol-3-phosphate acylation. Furthermore, the total flux for PC acyl editing, which includes both nascent and preexisting fatty acids, was estimated to be 1.5 to 5 times the flux of fatty acid synthesis. Thus, recycled acyl groups (16:0, 18:1, 18:2, and 18:3) in the acyl-coenzyme A pool provide most of the acyl chains for de novo glycerol-3-phosphate acylation. Our results also show kinetically distinct DAG pools. DAG used for TAG synthesis is mostly derived from PC, whereas de novo synthesized DAG is mostly used for PC synthesis. In addition, two kinetically distinct sn-3 acylations of DAG were observed, providing TAG molecular species enriched in saturated or polyunsaturated fatty acids.

Annual Meeting of the West Lakes Division of the Association of American
Geographers; Bloomington, IN; November 13-15, 2008.

AGROFUELS AND FOOD SYSTEMS: GEOGRAPHIC SCIENCE IN STUDY OF AGROECOSYSTEM SUSTAINABILITY

U.S. and global agriculture are entering a new era of increased and sometimes conflicting demands for multiple goods and services that include high-quality food & food systems, commodities production, environmental enhancement, economic growth and rural revitalization. The new era has been shaped by recent policies of globalized trade and technology, yet the challenges and opportunities of future agriculture are likely to be local and regional in effect. Simultaneously, energy security in the U.S., peak petroleum supplies and concerns for global climate change are increasing demands for agrofuels (e.g., ethanol and biodiesel). However, the ability of agrofuels to offset carbon dioxide emissions, and to decrease U.S. dependence on foreign oil, is uncertain. There is also increasing need to understand the impacts of increased agrofuel production over intermediate and longer terms, including: changes in food costs & availability; changes in human nutrition; challenges to food sovereignty and food justice; challenges to environmental health & safety; increased energy/fuel infrastructure & changes in distribution; soil loss & degradation; air & water quality degradation; changes in water access & use; challenges to labor and human rights; and challenges to rural vitality. Papers are welcomed which examine these or similar issues at scales from the local to the
global.

Papers could consider, but are not limited to:

Potential and/or limits of agrofuels; Carbon sequestration of agrofuel feedstocks; Agrofuel feedstock supplies; Agrofuel feedstock v food supplies; Energy consumption in agrofuel production & distribution, and/or food production & distribution; Environmental impacts of agrofuel production; Changes in food quality & quantity; Social issues of food production & access; Social issues in agrofuel production & access; Nutrition and diet change when food production is shifted to agrofuel production; Geopolitics of agrofuels, food and agriculture.

Please email submit abstracts to Carol L. Williams (willico@iastate.edu) by SEPTEMBER 30, 2008.

Information on the annual Meeting of the West Lakes Division of the
Association of American Geographers Bloomington, IN, November 13-15,
2008, can be found at: http://www.indiana.edu/~geog/wldaag.

Summary

Triacylglycerols produced by plants are one of the most energy-rich and abundant forms of reduced carbon available from nature. Given their chemical similarities, plant oils represent a logical substitute for conventional diesel, a non-renewable energy source. However, as plant oils are too viscous for use in modern diesel engines, they are converted to fatty acid esters. The resulting fuel is commonly referred to as biodiesel, and offers many advantages over conventional diesel. Chief among these is that biodiesel is derived from renewable sources. In addition, the production and subsequent consumption of biodiesel results in less greenhouse gas emission compared to conventional diesel. However, the widespread adoption of biodiesel faces a number of challenges. The biggest of these is a limited supply of biodiesel feedstocks. Thus, plant oil production needs to be greatly increased for biodiesel to replace a major proportion of the current and future fuel needs of the world. An increased understanding of how plants synthesize fatty acids and triacylglycerols will ultimately allow the development of novel energy crops. For example, knowledge of the regulation of oil synthesis has suggested ways to produce triacylglycerols in abundant non-seed tissues. Additionally, biodiesel has poor cold-temperature performance and low oxidative stability. Improving the fuel characteristics of biodiesel can be achieved by altering the fatty acid composition. In this regard, the generation of transgenic soybean lines with high oleic acid content represents one way in which plant biotechnology has already contributed to the improvement of biodiesel.

Read the full study here.

Summary

Plant cell walls represent the most abundant renewable resource on this planet. Despite their great abundance, only 2% of this resource is currently used by humans. Hence, research into the feasibility of using plant cell walls in the production of cost-effective biofuels is desirable. The main bottleneck for using wall materials is the recalcitrance of walls to efficient degradation into fermentable sugars. Manipulation of the wall polysaccharide biosynthetic machinery or addition of wall structure-altering agents should make it possible to tailor wall composition and architecture to enhance sugar yields upon wall digestion for biofuel fermentation. Study of the biosynthetic machinery and its regulation is still in its infancy and represents a major scientific and technical research challenge. Of course, any change in wall structure to accommodate cost-efficient biofuel production may have detrimental effects on plant growth and development due to the diverse roles of walls in the life of a plant. However, the diversity and abundance of wall structures present in the plant kingdom gives hope that this challenge can be met.

Read the full study here.