Dataset Information

Gene expression profiling in peanut using high density oligonucleotide microarrays.

ABSTRACT:

Background

Transcriptome expression analysis in peanut to date has been limited to a relatively small set of genes and only recently has a significant number of ESTs been released into the public domain. Utilization of these ESTs for oligonucleotide microarrays provides a means to investigate large-scale transcript responses to a variety of developmental and environmental signals, ultimately improving our understanding of plant biology.

Results

We have developed a high-density oligonucleotide microarray for peanut using 49,205 publicly available ESTs and tested the utility of this array for expression profiling in a variety of peanut tissues. To identify putatively tissue-specific genes and demonstrate the utility of this array for expression profiling in a variety of peanut tissues, we compared transcript levels in pod, peg, leaf, stem, and root tissues. Results from this experiment showed 108 putatively pod-specific/abundant genes, as well as transcripts whose expression was low or undetected in pod compared to peg, leaf, stem, or root. The transcripts significantly over-represented in pod include genes responsible for seed storage proteins and desiccation (e.g., late-embryogenesis abundant proteins, aquaporins, legumin B), oil production, and cellular defense. Additionally, almost half of the pod-abundant genes represent unknown genes allowing for the possibility of associating putative function to these previously uncharacterized genes.

Conclusion

The peanut oligonucleotide array represents the majority of publicly available peanut ESTs and can be used as a tool for expression profiling studies in diverse tissues.

SUBMITTER: Payton P

PROVIDER: S-EPMC2703657 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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Publications

Gene expression profiling in peanut using high density oligonucleotide microarrays.

Payton Paxton P Kottapalli Kameswara Rao KR Rowland Diane D Faircloth Wilson W Guo Baozhu B Burow Mark M Puppala Naveen N Gallo Maria M

BMC genomics 20090612

<h4>Background</h4>Transcriptome expression analysis in peanut to date has been limited to a relatively small set of genes and only recently has a significant number of ESTs been released into the public domain. Utilization of these ESTs for oligonucleotide microarrays provides a means to investigate large-scale transcript responses to a variety of developmental and environmental signals, ultimately improving our understanding of plant biology.<h4>Results</h4>We have developed a high-density oli ...[more]

PMID: 19523230

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Project description:To gain insights into molecular mechanisms of tolerance to heat stress, we conducted a transcript profiling experiment to identify heat-responsive genes in contrasting peanut mini core accessions, either un-acclimated or acclimated to heat stress. Plants at reproductive stage were exposed to 28 °C (control), 45 °C for 15 d (un-acclimated) or 45 °C for 1 d followed by 7 d recovery and 15 d stress (acclimated). Two contrasting genotypes showing diverse response to stress were selected based on a bioassay involving chlorophyll fluorescence yield under elevated respiratory demand and membrane thermostability. Transcript profiling was performed using 4 x 44k custom oligo microarrays containing 22k peanut EST sequences. The microarray analysis identified 710 stress-induced and 770 stress-repressed putative heat-responsive transcripts in the tolerant genotype. Gene enrichment analysis was performed using Blast2GO program and genes with homology to known proteins were categorized into detailed molecular functional groups. Majority of stress-responsive genes assigned to KEGG pathways belonged to starch, sucrose and galactose metabolism followed by amino acid metabolism, and secondary metabolite biosynthesis. Differentially expressed transcripts from samples obtained from first year’s experiment were validated in the samples from second year by quantitative real-time PCR. Transcripts of eight genes involved in terpenoid and flavanoid biosynthesis were induced after second and seventh day, respectively, in leaves under heat stress. Metabolite analysis confirmed increases in metabolites of selected pathways under heat stress. The heat up-regulated genes in tolerant COC041 mini-core accession are potential candidate genes for engineering stress-tolerant peanuts and unraveling molecular mechanisms of peanut adaptation to heat stress. We used Agilent peanut microarrays to identify putative heat stress-responsive genes. Directly heat-stressed leaf tissues of the peanut genotypes COC041 (tolerant) and COC166 (susceptible) were used in the study. Three replications of microarray experiments were carried out by hybridizing the cRNA from different time points and stress conditions in a loop design on 4 x 44k microarray.

Project description:BACKGROUND: Gene expression profiles of non-model mammals may provide valuable data for biomedical and evolutionary studies. However, due to lack of sequence information of other species, DNA microarrays are currently restricted to humans and a few model species. This limitation may be overcome by using arrays developed for a given species to analyse gene expression in a related one, an approach known as "cross-species analysis". In spite of its potential usefulness, the accuracy and reproducibility of the gene expression measures obtained in this way are still open to doubt. The present study examines whether or not hybridization values from cross-species analyses are as reproducible as those from same-species analyses when using Affymetrix oligonucleotide microarrays. RESULTS: The reproducibility of the probe data obtained hybridizing deer, Old-World primates, and human RNA samples to Affymetrix human GeneChip U133 Plus 2.0 was compared. The results show that cross-species hybridization affected neither the distribution of the hybridization reproducibility among different categories, nor the reproducibility values of the individual probes. Our analyses also show that a 0.5% of the probes analysed in the U133 plus 2.0 GeneChip are significantly associated to un-reproducible hybridizations. Such probes-called in the text un-reproducible probe sequences- do not increase in number in cross-species analyses. CONCLUSION: Our study demonstrates that cross-species analyses do not significantly affect hybridization reproducibility of GeneChips, at least within the range of the mammal species analysed here. The differences in reproducibility between same-species and cross-species analyses observed in previous studies were probably caused by the analytical methods used to calculate the gene expression measures. Together with previous observations on the accuracy of GeneChips for cross-species analysis, our analyses demonstrate that cross-species hybridizations may provide useful gene expression data. However, the reproducibility and accuracy of these measures largely depends on the use of appropriated algorithms to derive the gene expression data from the probe data. Also, the identification of probes associated to un-reproducible hybridizations-useless for gene expression analyses- in the studied GeneChip, stress the need of a re-evaluation of the probes' performance.

Dataset Information

Gene expression profiling in peanut using high density oligonucleotide microarrays.

Background

Results

Conclusion

Publications

Gene expression profiling in peanut using high density oligonucleotide microarrays.

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