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Richard A. Dixon

Other affiliations: Fermilab, University of Texas at Austin, University of Georgia  ...read more
Bio: Richard A. Dixon is an academic researcher from University of North Texas. The author has contributed to research in topics: Elicitor & Lignin. The author has an hindex of 126, co-authored 603 publications receiving 71424 citations. Previous affiliations of Richard A. Dixon include Fermilab & University of Texas at Austin.


Papers
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Journal ArticleDOI
TL;DR: Limiting discussion to stress-induced phenylpropanoids eliminates few of the structural classes, because many compounds that are constitutive in one plant species or tissue can be induced by various stresses in another species or in another tissue of the same plant.
Abstract: Phenylpropanoid compounds encompass a wide range of structural classes and biological functions. Limiting discussion to stress-induced phenylpropanoids eliminates few of the structural classes, because many compounds thst are constitutive in one plant species or tissue can be induced by various stresses in another species or in another tissue of the same plant (Beggs et al., 1987; Christie et al., 1994).

4,046 citations

Journal ArticleDOI
01 Jun 1997
TL;DR: Emerging data indicate that the oxidative burst reflects activation of a membrane-bound NADPH oxidase closely resembling that operating in activated neutrophils, which underlies the expression of disease-resistance mechanisms.
Abstract: Rapid generation of superoxide and accumulation of H2O2 is a characteristic early feature of the hypersensitive response following perception of pathogen avirulence signals. Emerging data indicate that the oxidative burst reflects activation of a membrane-bound NADPH oxidase closely resembling that operating in activated neutrophils. The oxidants are not only direct protective agents, but H2O2 also functions as a substrate for oxidative cross-linking in the cell wall, as a threshold trigger for hypersensitive cell death, and as a diffusible signal for induction of cellular protectant genes in surrounding cells. Activation of the oxidative burst is a central component of a highly amplified and integrated signal system, also involving salicylic acid and perturbations of cytosolic Ca2+, which underlies the expression of disease-resistance mechanisms.

3,203 citations

Journal ArticleDOI
16 May 2014-Science
TL;DR: Recent developments in genetic engineering, enhanced extraction methods, and a deeper understanding of the structure of lignin are yielding promising opportunities for efficient conversion of this renewable resource to carbon fibers, polymers, commodity chemicals, and fuels.
Abstract: Background Lignin, nature’s dominant aromatic polymer, is found in most terrestrial plants in the approximate range of 15 to 40% dry weight and provides structural integrity. Traditionally, most large-scale industrial processes that use plant polysaccharides have burned lignin to generate the power needed to productively transform biomass. The advent of biorefineries that convert cellulosic biomass into liquid transportation fuels will generate substantially more lignin than necessary to power the operation, and therefore efforts are underway to transform it to value-added products. Production of biofuels from cellulosic biomass requires separation of large quantities of the aromatic polymer lignin. In planta genetic engineering, enhanced extraction methods, and a deeper understanding of the structure of lignin are yielding promising opportunities for efficient conversion of this renewable resource to carbon fibers, polymers, commodity chemicals, and fuels. [Credit: Oak Ridge National Laboratory, U.S. Department of Energy] Advances Bioengineering to modify lignin structure and/or incorporate atypical components has shown promise toward facilitating recovery and chemical transformation of lignin under biorefinery conditions. The flexibility in lignin monomer composition has proven useful for enhancing extraction efficiency. Both the mining of genetic variants in native populations of bioenergy crops and direct genetic manipulation of biosynthesis pathways have produced lignin feedstocks with unique properties for coproduct development. Advances in analytical chemistry and computational modeling detail the structure of the modified lignin and direct bioengineering strategies for targeted properties. Refinement of biomass pretreatment technologies has further facilitated lignin recovery and enables catalytic modifications for desired chemical and physical properties. Outlook Potential high-value products from isolated lignin include low-cost carbon fiber, engineering plastics and thermoplastic elastomers, polymeric foams and membranes, and a variety of fuels and chemicals all currently sourced from petroleum. These lignin coproducts must be low cost and perform as well as petroleum-derived counterparts. Each product stream has its own distinct challenges. Development of renewable lignin-based polymers requires improved processing technologies coupled to tailored bioenergy crops incorporating lignin with the desired chemical and physical properties. For fuels and chemicals, multiple strategies have emerged for lignin depolymerization and upgrading, including thermochemical treatments and homogeneous and heterogeneous catalysis. The multifunctional nature of lignin has historically yielded multiple product streams, which require extensive separation and purification procedures, but engineering plant feedstocks for greater structural homogeneity and tailored functionality reduces this challenge.

2,958 citations

Journal ArticleDOI
18 Nov 1994-Cell
TL;DR: It is reported here that H2O2 from this oxidative burst not only drives the cross-linking of cell wall structural proteins, but also functions as a local trigger of programmed death in challenged cells and as a diffusible signal for the induction in adjacent cells of genes encoding cellular protectants.

2,740 citations

Journal ArticleDOI
06 Aug 1998-Nature
TL;DR: It is shown that nitric oxide potentiates the induction of hypersensitive cell death in soybean cells by reactive oxygen intermediates and functions independently of such intermediates to induce genes for the synthesis of protective natural products.
Abstract: Recognition of an avirulent pathogen triggers the rapid production of the reactive oxygen intermediates superoxide (O2-) and hydrogen peroxide (H2O2) This oxidative burst drives crosslinking of the cell wall, induces several plant genes involved in cellular protection and defence, and is necessary for the initiation of host cell death in the hypersensitive disease-resistance response However, this burst is not enough to support a strong disease-resistance response Here we show that nitric oxide, which acts as a signal in the immune, nervous and vascular systems, potentiates the induction of hypersensitive cell death in soybean cells by reactive oxygen intermediates and functions independently of such intermediates to induce genes for the synthesis of protective natural products Moreover, inhibitors of nitric oxide synthesis compromise the hypersensitive disease-resistance response of Arabidopsis leaves to Pseudomonas syringae, promoting disease and bacterial growth We conclude that nitric oxide plays a key role in disease resistance in plants

1,821 citations


Cited by
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Journal ArticleDOI
23 Jan 2004-Cell
TL;DR: Although they escaped notice until relatively recently, miRNAs comprise one of the more abundant classes of gene regulatory molecules in multicellular organisms and likely influence the output of many protein-coding genes.

32,946 citations

28 Jul 2005
TL;DR: PfPMP1)与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1(PfPMP1)与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用,在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员,通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

18,940 citations

Journal ArticleDOI
TL;DR: The mechanisms of ROS generation and removal in plants during development and under biotic and abiotic stress conditions are described and the possible functions and mechanisms for ROS sensing and signaling in plants are compared with those in animals and yeast.
Abstract: Several reactive oxygen species (ROS) are continuously produced in plants as byproducts of aerobic metabolism. Depending on the nature of the ROS species, some are highly toxic and rapidly detoxified by various cellular enzymatic and nonenzymatic mechanisms. Whereas plants are surfeited with mechanisms to combat increased ROS levels during abiotic stress conditions, in other circumstances plants appear to purposefully generate ROS as signaling molecules to control various processes including pathogen defense, programmed cell death, and stomatal behavior. This review describes the mechanisms of ROS generation and removal in plants during development and under biotic and abiotic stress conditions. New insights into the complexity and roles that ROS play in plants have come from genetic analyses of ROS detoxifying and signaling mutants. Considering recent ROS-induced genome-wide expression analyses, the possible functions and mechanisms for ROS sensing and signaling in plants are compared with those in animals and yeast.

9,908 citations

Journal ArticleDOI
TL;DR: Key steps of the signal transduction pathway that senses ROIs in plants have been identified and raise several intriguing questions about the relationships between ROI signaling, ROI stress and the production and scavenging ofROIs in the different cellular compartments.

9,395 citations

Journal ArticleDOI
TL;DR: There is growing evidence that aging involves, in addition, progressive changes in free radical-mediated regulatory processes that result in altered gene expression.
Abstract: At high concentrations, free radicals and radical-derived, nonradical reactive species are hazardous for living organisms and damage all major cellular constituents. At moderate concentrations, how...

9,131 citations