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1985 Full-Text Articles 3323 Authors 186691 Downloads 57 Institutions

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1985 full-text articles. Page 1 of 40.

Parsing A Multifunctional Biosynthetic Gene Cluster From Rice: Biochemical Characterization Of Cyp71z6 & 7, Yinsheng Wu, Matthew L. Hillwig, Qiang Wang, Reuben J. Peters 2017 Iowa State University

Parsing A Multifunctional Biosynthetic Gene Cluster From Rice: Biochemical Characterization Of Cyp71z6 & 7, Yinsheng Wu, Matthew L. Hillwig, Qiang Wang, Reuben J. Peters

Reuben J. Peters

Rice (Oryza sativa) contains a biosynthetic gene cluster associated with production of at least two groups of diterpenoid phytoalexins, the antifungal phytocassanes and antibacterial oryzalides. While cytochromes P450 (CYP) from this cluster are known to be involved in phytocassane production, such mono-oxygenase activity relevant to oryzalide biosynthesis was unknown. Here we report biochemical characterization demonstrating that CYP71Z6 from this cluster acts as an ent-isokaurene C2-hydroxylase that is presumably involved in the biosynthesis of oryzalides. Our results further suggest that the closely related and co-clustered CYP71Z7 likely acts as a C2- hydroxylase involved in a latter step of phytocassane biosynthesis. Thus ...


Cyp99a3: Functional Identification Of A Diterpene Oxidase From The Momilactone Biosynthetic Gene Cluster In Rice, Qiang Wang, Matthew L. Hillwig, Reuben J. Peters 2017 Iowa State University

Cyp99a3: Functional Identification Of A Diterpene Oxidase From The Momilactone Biosynthetic Gene Cluster In Rice, Qiang Wang, Matthew L. Hillwig, Reuben J. Peters

Reuben J. Peters

Rice (Oryza sativa) produces momilactone diterpenoids as both phytoalexins and allelochemicals. Strikingly, the rice genome contains a biosynthetic gene cluster for momilactone production, located on rice chromosome 4, which contains two cytochromes P450 mono-oxygenases, CYP99A2 and CYP99A3, with undefined roles; although it has been previously shown that RNAi double knock-down of this pair of closely related CYP reduced momilactone accumulation. Here we attempted biochemical characterization of CYP99A2 and CYP99A3, which ultimately was achieved by complete gene recoding, enabling functional recombinant expression in bacteria. With these synthetic gene constructs it was possible to demonstrate that, while CYP99A2 does not exhibit significant ...


Characterization Of Cyp76m5–8 Indicates Metabolic Plasticity Within A Plant Biosynthetic Gene Cluster, Qiang Wang, Matthew L. Hillwig, Kazunori Okada, Kohei Yamazaki, Yisheng Wu, Sivakumar Swaminathan, Hisakazu Yamane, Reuben J. Peters 2017 Iowa State University

Characterization Of Cyp76m5–8 Indicates Metabolic Plasticity Within A Plant Biosynthetic Gene Cluster, Qiang Wang, Matthew L. Hillwig, Kazunori Okada, Kohei Yamazaki, Yisheng Wu, Sivakumar Swaminathan, Hisakazu Yamane, Reuben J. Peters

Reuben J. Peters

Recent reports have revealed genomic clustering of enzymatic genes for particular biosynthetic pathways in plant specialized/secondary metabolism. Rice (Oryza sativa) carries two such clusters for production of antimicrobial diterpenoid phytoalexins, with the cluster on chromosome 2 containing four closely related/homologous members of the cytochrome P450 CYP76M subfamily (CYP76M5–8). Notably, the underlying evolutionary expansion of these CYP appears to have occurred after assembly of the ancestral biosynthetic gene cluster, suggesting separate roles. It has been demonstrated that CYP76M7 catalyzes C11α-hydroxylation of ent-cassadiene, and presumably mediates an early step in biosynthesis of the derived phytocassane class of phytoalexins. Here ...


Domain Loss Has Independently Occurred Multiple Times In Plant Terpene Synthase Evolution, Matthew L. Hillwig, Meimei Xu, Tomonobu Toyomasu, Mollie S. Tiernan, Gao Wei, Guanghong Cui, Luqi Huang, Reuben J. Peters 2017 Iowa State University

Domain Loss Has Independently Occurred Multiple Times In Plant Terpene Synthase Evolution, Matthew L. Hillwig, Meimei Xu, Tomonobu Toyomasu, Mollie S. Tiernan, Gao Wei, Guanghong Cui, Luqi Huang, Reuben J. Peters

Reuben J. Peters

The extensive family of plant terpene synthases (TPSs) generally has a bi-domain structure, yet phylogenetic analyses consistently indicate that these evolved from larger diterpene synthases. In particular, that duplication of the diterpene synthase genes required for gibberellin phytohormone biosynthesis provided an early predecessor, whose loss of a ~220 amino acid “internal sequence element” (now recognized as the γ domain) gave rise to the precursor of modern mono- and sesqui-TPSs found in all higher plants. Intriguingly, TPSs are conserved by taxonomic relationships rather than function, demonstrating that such functional radiation has occurred both repeatedly and relatively recently, yet phylogenetic analyses assume ...


Genetic Evidence For Natural Product-Mediated Plant–Plant Allelopathy In Rice (Oryza Sativa), Meimei Xu, Rita Galhano, Philipp Wiemann, Emilio Bueno, Mollie Tiernan, William Wu, Ill-Min Chung, Jonathan Gershenzon, Bettina Tudzynski, Ane Sesma, Reuben J. Peters 2017 Iowa State University

Genetic Evidence For Natural Product-Mediated Plant–Plant Allelopathy In Rice (Oryza Sativa), Meimei Xu, Rita Galhano, Philipp Wiemann, Emilio Bueno, Mollie Tiernan, William Wu, Ill-Min Chung, Jonathan Gershenzon, Bettina Tudzynski, Ane Sesma, Reuben J. Peters

Reuben J. Peters

• A role for specific natural products in directly mediating antagonistic plant–plant interactions –that is, allelopathy –has been controversial. If proven, such phenomena would hold considerable promise for agronomic improvement of staple food crops such as rice (Oryza sativa)

• However, while substantiated by the presence of phytotoxic compounds at potentially relevant levels, demonstrating a direct role for specific natural products in allelopathy has been difficult due to the chemical complexity of root and plant litter exudates. This complexity can be bypassed via selective genetic manipulation to ablate production of putative allelopathic compounds, but such an approach previously has not been ...


Product Rearrangement From Altering A Single Residue In The Rice Syn-Copalyl Diphosphate Synthase, Kevin C. Potter, Meirong Jia, Young J. Hong, Dean Tantillo, Reuben J. Peters 2017 Iowa State University

Product Rearrangement From Altering A Single Residue In The Rice Syn-Copalyl Diphosphate Synthase, Kevin C. Potter, Meirong Jia, Young J. Hong, Dean Tantillo, Reuben J. Peters

Reuben J. Peters

Through site-directed mutagenesis targeted at identification of the catalytic base in the rice (Oryza sativa) syn-copalyl diphosphate synthase OsCPS4, changes to a single residue (H501) were found to induce rearrangement rather than immediate deprotonation of the initially formed bicycle, leading to production of the novel compound syn-halimadienyl diphosphate. These mutational results are combined with quantum chemical calculations to provide insight into the underlying reaction mechanism.


Biosynthesis, Elicitation And Roles Of Monocot Terpenoid Phytoalexins, Eric A. Schmelz, Alisa Huffaker, James W. Sims, Shawn A. Christensen, Xuan Lu, Kuzunori Okada, Reuben J. Peters 2017 United States Department of Agriculture

Biosynthesis, Elicitation And Roles Of Monocot Terpenoid Phytoalexins, Eric A. Schmelz, Alisa Huffaker, James W. Sims, Shawn A. Christensen, Xuan Lu, Kuzunori Okada, Reuben J. Peters

Reuben J. Peters

A long-standing goal in plant research is to optimize the protective function of biochemical agents that impede pest and pathogen attack. Nearly 40 years ago, pathogen-inducible diterpenoid production was described in rice, and these compounds were shown to function as antimicrobial phytoalexins. Using rice and maize as examples, we discuss recent advances in the discovery, biosynthesis, elicitation and functional characterization of monocot terpenoid phytoalexins. The recent expansion of known terpenoid phytoalexins now includes not only the labdane-related diterpenoid superfamily but also casbane-type diterpenoids and β-macrocarpene-derived sequiterpenoids. Biochemical approaches have been used to pair pathway precursors and end products with cognate ...


The Application Of Synthetic Biology To Elucidation Of Plant Mono-, Sesqui-, And Diterpenoid Metabolism, Naoki Kitaoka, Xuan Lu, Bing Yang, Reuben J. Peters 2017 Iowa State University

The Application Of Synthetic Biology To Elucidation Of Plant Mono-, Sesqui-, And Diterpenoid Metabolism, Naoki Kitaoka, Xuan Lu, Bing Yang, Reuben J. Peters

Reuben J. Peters

Plants synthesize a huge variety of terpenoid natural products, including photosynthetic pigments, signaling molecules and defensive substances. These are often produced as complex mixtures, presumably shaped by selective pressure over evolutionary timescales, some of which have been found to have pharmaceutical and other industrial uses. Elucidation of the relevant biosynthetic pathways can provide increased access (e.g., via molecular breeding or metabolic engineering), and enable reverse genetic approaches towards understanding the physiological role of these natural products in plants as well. While such information can be obtained via a variety of approaches, this review describes the emerging use of synthetic ...


Identification Of A Dolabellane Type Diterpene Synthase And Other Root-Expressed Diterpene Synthases In Arabidopsis, Qiang Wang, Meirong Jia, Jung-Hyun Huh, Andrew Muchlinski, Reuben J. Peters, Dorothea Tholl 2017 Virginia Tech

Identification Of A Dolabellane Type Diterpene Synthase And Other Root-Expressed Diterpene Synthases In Arabidopsis, Qiang Wang, Meirong Jia, Jung-Hyun Huh, Andrew Muchlinski, Reuben J. Peters, Dorothea Tholl

Reuben J. Peters

Arabidopsis thaliana maintains a complex metabolism for the production of secondary or specialized metabolites. Such metabolites include volatile and semivolatile terpenes, which have been associated with direct and indirect defensive activities in flowers and leaves. In comparison, the structural diversity and function of terpenes in Arabidopsis roots has remained largely unexplored despite a substantial number of root-expressed genes in the Arabidopsis terpene synthase (TPS) gene family. We show that five root-expressed TPSs of an expanded subfamily-a type clade in the Arabidopsis TPS family function as class I diterpene synthases that predominantly convert geranylgeranyl diphosphate (GGPP) to different semi-volatile diterpene products ...


Optimization Of Recombinant Expression Enables Discovery Of Novel Cytochrome P450 Activity In Rice Diterpenoid Biosynthesis, Naoki Kitaoka, Yisheng Wu, Meimei Xu, Reuben J. Peters 2017 Iowa State University

Optimization Of Recombinant Expression Enables Discovery Of Novel Cytochrome P450 Activity In Rice Diterpenoid Biosynthesis, Naoki Kitaoka, Yisheng Wu, Meimei Xu, Reuben J. Peters

Reuben J. Peters

The oxygenation reactions catalyzed by cytochromes P450 (CYPs) play critical roles in plant natural products biosynthesis. At the same time, CYPs are one of most challenging enzymes to functionally characterize due to the difficulty of recombinantly expressing these membrane-associated monooxygenases. In the course of investigating rice diterpenoid biosynthesis we have developed a synthetic biology approach for functional expression of relevant CYPs in Escherichia coli. In certain cases activity was observed for only one of two closely related paralogs although it seems clear that related reactions are required for production of the known diterpenoids. Here we report that optimization of the ...


Biochemical Characterization Of The Castor Bean Ent-Kaurene Synthase(-Like) Family Supports Quantum Chemical View Of Diterpene Cyclization, Alana J. Jackson, David M. Hershey, Taylor Chesnut, Meimei Xu, Reuben J. Peters 2017 Iowa State University

Biochemical Characterization Of The Castor Bean Ent-Kaurene Synthase(-Like) Family Supports Quantum Chemical View Of Diterpene Cyclization, Alana J. Jackson, David M. Hershey, Taylor Chesnut, Meimei Xu, Reuben J. Peters

Reuben J. Peters

It has become apparent that plants have extensively diversified their arsenal of labdane-related diterpenoids (LRDs), in part via gene duplication and neo-functionalization of the ancestral entkaurene synthase (KS) required for gibberellin metabolism. For example, castor bean (Ricinus communis) was previously shown to produce an interesting set of biosynthetically related diterpenes, specifically ent-sandracopimaradiene, ent-beyerene, and ent-trachylobane, in addition to ent-kaurene, using four separate diterpene synthases, albeit these remain unidentified. Notably, despite mechanistic similarity of the underlying reaction to that catalyzed by KSs, ent-beyerene and ent-trachylobane synthases have not yet been identified. Given our interest in LRD biosynthesis, and the recent availability ...


Extending A Single Residue Switch For Abbreviating Catalysis In Plant Ent-Kaurene Synthases, Meirong Jia, Reuben J. Peters 2017 Iowa State University

Extending A Single Residue Switch For Abbreviating Catalysis In Plant Ent-Kaurene Synthases, Meirong Jia, Reuben J. Peters

Reuben J. Peters

Production of ent-kaurene as a precursor for important signaling molecules such as the gibberellins seems to have arisen early in plant evolution, with corresponding cyclase(s) present in all land plants (i.e., embryophyta). The relevant enzymes seem to represent fusion of the class II diterpene cyclase that produces the intermediate ent-copalyl diphosphate (ent-CPP) and the subsequently acting class I diterpene synthase that produces ent-kaurene, although the bifunctionality of the ancestral gene is only retained in certain early diverging plants, with gene duplication and sub-functionalization leading to distinct ent-CPP synthases and ent-kaurene synthases (KSs) generally observed. This evolutionary scenario implies ...


Morphological Variation In The Wild-Weedy Complex Of Sorghum Bicolor In Situ In Western Kenya: Preliminary Evidence Of Crop-To-Wild Gene Flow?, James A. Okeno, Evans Mutegi, Santie de Villiers, Jeffrey D. Wolt, Manjit K. Misra 2017 Iowa State University

Morphological Variation In The Wild-Weedy Complex Of Sorghum Bicolor In Situ In Western Kenya: Preliminary Evidence Of Crop-To-Wild Gene Flow?, James A. Okeno, Evans Mutegi, Santie De Villiers, Jeffrey D. Wolt, Manjit K. Misra

Manjit K. Misra

Crop wild relatives are important components of agroecosystems and have over the years been exploited in breeding programs as sources of genes for novel traits. Information on the extent and patterns of variability is important in formulating effective conservation and utilization strategies for existing crop wild relative populations. We conducted surveys and collections of wild and weedy accessions of Sorghum bicolor (L.) Moench in Lambwe Valley in western Kenya in order to investigate occurrence, distribution, and morphological variability in the wild-weedy complex of S. bicolor under local agroecological conditions. We also attempted to understand the role, if any, of crop-to-wild ...


The Maize (Zea Mays L.) Roothairless3 Gene Encodes A Putative Gpi-Anchored, Monocot-Specific, Cobra-Like Protein That Significantly Affects Grain Yield, Frank Hochholdinger, Tsui-Jung Wen, Patricia Chimot-Marolle, Oswaldo Da Costa e Silva, Wesley Bruce, Kendall R. Lamkey, Udo Wienand, Patrick S. Schnable 2017 Eberhard Karls Universität Tübingen

The Maize (Zea Mays L.) Roothairless3 Gene Encodes A Putative Gpi-Anchored, Monocot-Specific, Cobra-Like Protein That Significantly Affects Grain Yield, Frank Hochholdinger, Tsui-Jung Wen, Patricia Chimot-Marolle, Oswaldo Da Costa E Silva, Wesley Bruce, Kendall R. Lamkey, Udo Wienand, Patrick S. Schnable

Kendall R Lamkey

The rth3 (roothairless 3) mutant is specifically affected in root hair elongation. We report here the cloning of the rth3 gene via a PCR-based strategy (amplification of insertion mutagenized sites) and demonstrate that it encodes a COBRA-like protein that displays all the structural features of a glycosylphosphatidylinositol anchor. Genes of the COBRA family are involved in various types of cell expansion and cell wall biosynthesis. The rth3 gene belongs to a monocot-specific clade of the COBRA gene family comprising two maize and two rice genes. While the rice (Oryza sativa) gene OsBC1L1 appears to be orthologous to rth3 based on ...


Temporal Changes In Allele Frequencies In Two Reciprocally Selected Maize Populations, J. A. Labate, Kendall R. Lamkey, Michael Lee, W. L. Woodman 2017 United States Department of Agriculture

Temporal Changes In Allele Frequencies In Two Reciprocally Selected Maize Populations, J. A. Labate, Kendall R. Lamkey, Michael Lee, W. L. Woodman

Kendall R Lamkey

The effects of breeding on allele frequency changes at 82 restriction fragment length polymorphism (RFLP) loci were examined in two maize (Zea mays L.) populations undergoing reciprocal recurrent selection, Iowa Stiff Stalk Synthetic and Iowa Corn Borer Synthetic #1. After 12 cycles of selection, approximately 30% of the alleles were extinct and 10% near fixation in each population. A test of selective neutrality identified several loci in each population whose allele frequency changes cannot be explained by genetic drift; interpopulation mean expected heterozygosity increased for that subset of 28 loci but not for the remaining 54 loci. Mean expected heterozygosity ...


Estimates Of Heterosis And Inbreeding Depression For Crosses Of Lowa Maize Populations, T. A. Scheffler, Arnel R. Hallauer, Kendall R. Lamkey, Paul R. White 2017 Iowa State University

Estimates Of Heterosis And Inbreeding Depression For Crosses Of Lowa Maize Populations, T. A. Scheffler, Arnel R. Hallauer, Kendall R. Lamkey, Paul R. White

Kendall R Lamkey

Relative success of maize (Zea mays L.) breeding programs depends on the proper choice of parental germplasm and the recognition and the use of heterotic groups. Our objective was to identify maize populations with exotic germplasm that would be potentially useful germplasm sources in temperate area maize breeding programs. A factorial mating design was used to produce 35 crosses between seven Iowa Stiff Stalk Synthetic and five non-Iowa Stiff Stalk Synthetic populations. The 12 parental populations and their 35 population crosses also were selfed to produce F2 generation. The two sets of genetic materials were evaluated at five Iowa locations ...


Recurrent Selection To Alter Grain Methionine Concentration And Improve Nutritional Value Of Maize, M. Paul Scott, Audrey Darrigues, Timothy S. Stahly, Kendall R. Lamkey 2017 United States Department of Agriculture

Recurrent Selection To Alter Grain Methionine Concentration And Improve Nutritional Value Of Maize, M. Paul Scott, Audrey Darrigues, Timothy S. Stahly, Kendall R. Lamkey

Kendall R Lamkey

Methionine is an essential amino acid that is limiting in maize- (Zea mays L.) based diets. The objective of this work was to determine whether we could alter grain methionine concentration in random-mated maize populations by mass selection for methionine concentration using a microbial assay. In one study, we developed two populations by selecting for high or low methionine concentration (HM or LM, respectively) for three generations starting from the random-mated population BS11. Grain from these populations was used to formulate diets for a feeding trial in which 15 rats were fed HM grain and 15 rats were fed LM ...


Strategies For The Production Of Maize-Derived Pharmaceuticals Using Cytoplasmic Male Sterile Lines: In Vitro Tissue Culture/Transformation And Field Breeding Approaches, Kan Wang, Bronwyn R. Frame, X. Xu, Kendall R. Lamkey 2017 Iowa State University

Strategies For The Production Of Maize-Derived Pharmaceuticals Using Cytoplasmic Male Sterile Lines: In Vitro Tissue Culture/Transformation And Field Breeding Approaches, Kan Wang, Bronwyn R. Frame, X. Xu, Kendall R. Lamkey

Kendall R Lamkey

Plant-made pharmaceuticals (PMPs) offer promise as efficient and cost-effective products for the treatment of human and animal diseases. An advantage of producing pharmaceuticals in maize is the large storage capacity and stability for proteins and starch in seed, allowing for manufacturing recombinant proteins such as antigens and antibodies. Other advantages of the maize system include safety, high yields, and scalability of production and processing. However, the benefits of this technology must be balanced against potential health and environmental risks that may be associated with its use. Because PMPs presently have no provision for regulatory tolerance, their inadvertent occurrence in foods ...


Storage Of Molecular Marker Data In Databases For Efficient Use In Plant Breeding Programs, Matthias Frisch, Kendall R. Lamkey, Albrecht E. Melchinger 2017 Universität Hohenheim

Storage Of Molecular Marker Data In Databases For Efficient Use In Plant Breeding Programs, Matthias Frisch, Kendall R. Lamkey, Albrecht E. Melchinger

Kendall R Lamkey

With the increased use of molecular markers in plant breeding programs, appropriate storage of these data becomes an important issue. The concept for storage of molecular marker data in databases proposed in this paper is simple and generic so that it can be implemented on a personal computer and integrated in large-scale database systems. Application of the proposed data structure simplifies standardized statistical analyses and reanalyses of experimental data as well as data exchange and reuse of programmed analysis routines.


Population Genetic Diversity In A Maize Reciprocal Recurrent Selection Program, Lori L. Hinze, Stephen Kresovich, John D. Nason, Kendall R. Lamkey 2017 United States Department of Agriculture

Population Genetic Diversity In A Maize Reciprocal Recurrent Selection Program, Lori L. Hinze, Stephen Kresovich, John D. Nason, Kendall R. Lamkey

Kendall R Lamkey

The genetic structures of the Iowa Corn Borer Synthetic #1 (CB) and Iowa Stiff Stalk Synthetic (SS) maize (Zea mays L.) populations are important because these populations serve as the model for development of modern commercial hybrids. In 1949, CB and SS were used to start a reciprocal recurrent selection (RRS) breeding program at Iowa State University. This study was conducted to analyze more thoroughly the genetic diversity within this RRS program and illustrate how the RRS program has changed over time at the molecular level. The progress of this program was measured by analyzing the variation at 86 SSR ...


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