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Jeffrey F D Dean

Publications and source records attributed to Jeffrey F D Dean.

6 recordsLinked to original sources
PubMed2006

Water stress-responsive genes in loblolly pine (Pinus taeda) roots identified by analyses of expressed sequence tag libraries.

Drought stress is the principal cause of seedling mortality in pine forests of the southeastern United States and in many other forested regions around the globe. As part of a larger effort to discover loblolly pine genes, this study subjected rooted cuttings of three unrelated pine genotypes to three watering regimens. Expressed sequence tags (ESTs) were obtained from both the 3' and 5' ends of 12,918 randomly selected cDNAs generated from root tissues. These ESTs were clustered to identify 6,765 unique transcripts (UniScripts) derived from 6,202 putative unique genes (UniGenes-S). Tentative annotations were assigned on the basis of BLASTX comparisons to the Protein Information Resource Nonredundant Reference (PIR-NREF) database. Expression levels of 42 UniScripts varied with high statistical significance with respect to treatment. Many of them resembled gene products shown to be important for drought tolerance in other species, including dehydrins, endochitinases, cytochrome P450 enzymes, pathogenesis-related proteins and various late-embryogenesis abundant (LEA) gene products. Similarly, expression levels of 110 UniScripts varied with high statistical significance among genotypes, indicating that gene expression patterns in this species are much more dependent on genotype than on treatment. Most of the water stress-induced pine UniScripts that appeared to encode products resembling drought tolerance factors in other species were most highly induced in a single genotype, suggesting that particularly useful adaptive alleles for drought tolerance might exist within the collection of cDNAs characterized from this genotype. Mining and visualizing the complete data set, as well as downloading of both EST and UniScript contig sequences, are possible using MAGIC Gene Discovery at http://fungen.org/genediscovery/.

Acclimatization↗
PubMed2005

Gene expression changes in Arabidopsis thaliana seedling roots exposed to the munition hexahydro-1,3,5-trinitro-1,3,5-triazine.

Arabidopsis thaliana root transcriptome responses to the munition, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), were assessed using serial analysis of gene expression (SAGE). Sequencing of SAGE libraries from control and RDX-exposed root tissues revealed induction of genes known to respond to a variety of general stresses. Among the highly induced genes were several encoding molecular chaperones and transcription factors as well as vacuolar proteins and peroxidases. Strongly repressed transcripts included ones encoding ribosomal proteins, a cyclophilin, a katanin, and a peroxidase. Comparison of the transcriptional profile for the RDX response to a profile previously described for Arabidopsis roots exposed to trinitrotoluene (TNT) revealed significant differences in the inferred gene expression patterns. This suggests that Arabidopsis employs drastically different mechanisms for coping with these two compounds. With respect to the goal of engineering plants to better tolerate and degrade explosives at contaminated sites, these results suggest that enhancement of different genes and metabolic pathways may be required to deal effectively with each type of explosive. This has ramifications for phytoremediation efforts since many contaminated sites harbor both compounds.

Adaptation, Physiological↗
PubMed2005

Gene structure and molecular analysis of the laccase-like multicopper oxidase (LMCO) gene family in Arabidopsis thaliana.

Completed genome sequences have made it clear that multicopper oxidases related to laccase are widely distributed as multigene families in higher plants. Laccase-like multicopper oxidase (LMCO) sequences culled from GenBank and the Arabidopsis thaliana genome, as well as those from several newly cloned genes, were used to construct a gene phylogeny that clearly divided plant LMCOs into six distinct classes, at least three of which predate the evolutionary divergence of angiosperms and gymnosperms. Alignments of the predicted amino acid sequences highlighted regions of variable sequence flanked by the highly conserved copper-binding domains that characterize members of this enzyme family. All of the predicted proteins contained apparent signal sequences. The expression of 13 of the 17 LMCO genes in A. thaliana was assessed in different tissues at various stages of development using RT-PCR. A diversity of expression patterns was demonstrated with some genes being expressed in a constitutive fashion, while others were only expressed in specific tissues at a particular stage of development. Only a few of the LMCO genes were expressed in a pattern that could be considered consistent with a major role for these enzymes in lignin deposition. These results are discussed in the context of other potential physiological functions for plant LMCOs, such as iron metabolism and wound healing.

Amino Acid Sequence↗
PubMed2003

SAGE analysis of transcriptome responses in Arabidopsis roots exposed to 2,4,6-trinitrotoluene.

Serial analysis of gene expression was used to profile transcript levels in Arabidopsis roots and assess their responses to 2,4,6-trinitrotoluene (TNT) exposure. SAGE libraries representing control and TNT-exposed seedling root transcripts were constructed, and each was sequenced to a depth of roughly 32,000 tags. More than 19,000 unique tags were identified overall. The second most highly induced tag (27-fold increase) represented a glutathione S-transferase. Cytochrome P450 enzymes, as well as an ABC transporter and a probable nitroreductase, were highly induced by TNT exposure. Analyses also revealed an oxidative stress response upon TNT exposure. Although some increases were anticipated in light of current models for xenobiotic metabolism in plants, evidence for unsuspected conjugation pathways was also noted. Identifying transcriptome-level responses to TNT exposure will better define the metabolic pathways plants use to detoxify this xenobiotic compound, which should help improve phytoremediation strategies directed at TNT and other nitroaromatic compounds.

ATP-Binding Cassette Transporters↗
PubMed2002

SAGE profiling and demonstration of differential gene expression along the axial developmental gradient of lignifying xylem in loblolly pine (Pinus taeda).

Wood formation has been studied extensively at the cellular and biochemical levels, but remains poorly understood with respect to gene expression and regulation. As a first step toward identifying genes specifically involved in wood formation and characterizing their roles in determining wood quality, serial analysis of gene expression (SAGE) was used to quantify gene expression in lignifying xylem from a single, 10-year-old loblolly pine (Pinus taeda L.). Two SAGE libraries were generated based on lignifying xylem isolated from either the upper (crown) or lower (base) portions of the trunk. Over 85,000 tags representing a maximum of 27,398 expressed genes were analyzed from the crown wood library, and more than 65,000 tags, representing a maximum of 25,983 expressed genes, were analyzed in the base wood library. Combining these data sets to reflect the sum of genes expressed in lignifying xylem, 150,855 tags were cataloged, representing a maximum of 42,641 different genes. Currently, this study represents the most extensive analysis of its kind in a higher plant and provides a quantitative description of the transcriptome representing the lignifying xylem of a 10-year-old loblolly pine.

DNA, Complementary↗