Project description:The pathogen Agrobacterium tumefaciens infects a broad range of plants, introducing the T-DNA into their genome. Contrary to all known bacterial phyto-pathogens, Agrobacterium lacks the hypersensitive response-inducing HRP genes although it introduces numerous proteins into the plant cell through a type IV secretion system. To understand the timing and extent of the plant transcriptional response to this unusual pathogen, we used an Arabidopsis 26-thousand gene oligonucleotide microarray. We inoculated Arabidopsis cell cultures with an oncogenic strain of Agrobacterium and analyzed four biological replicates to identify two robust sets of regulated genes, one induced and the other suppressed. In both cases, the response was distinct at 48 hours after infection, but not at 24 hours or earlier. The induced set includes genes encoding known defense proteins, the repressed set is enriched with genes characteristic of cell proliferation even though a growth arrest was not visible in the inoculated cultures. The analysis of the repressed genes revealed that the conserved upstream regulatory elements Frankiebox (a.k.a. “site II”) and Telobox are associated with the suppression of gene expression. The regulated gene sets should be useful in dissecting the signaling pathways in this plant-pathogen interaction. Keywords: Time-course of Agrobacterium infection
Project description:Arabidopsis thaliana and Arabidopsis lyrata are two closely related Brassicaceae species, which are used as models for plant comparative biology. They differ by lifestyle, predominant mating strategy, ecological niches and genome organization. To identify heat stress induced genes, we performed RNA-sequencing of rosette leaves from mock-treated, heat-stressed and heat-stressed-recoved plants of both species. Analysis of genetic element transcriptional changes in response to 6 hours of 37°C heat stress and 48 hours of recovery in Arabidopsis thaliana Col-0 and Arabidopsis lyrata MN47.
Project description:cea10-03_cyclocitral - analysis of arabidopsis transcriptome in response to b-cyclocitral treatment - Is beta--cyclocitral a bioactive molecule involved in stress response? - Analysis of Arabidopsis transcriptome in response to b-cyclocitral treatment.
Project description:To better understand the mechanisms involved in aluminum (Al) toxicity and tolerance in plants, microarray technology was used to evaluate changes in gene expression in Arabidopsis thaliana under Al stress. With the use of Affymetrix Arabidopsis ATH1 Genechip, a comparison of RNA expression profiles was made between control and Al-treated Arabidopsis seedlings. A total of 256 genes were identified as Al-responsive. Ninety-four genes were shown to be up-regulated and 162 were down-regulated; comprising 1.1% of the 24,000 Arabidopsis genes. Real-time RT-PCR was used to confirm the microarray data. RNAs associated with known protein functions were classified into categories. The analysis showed that a large number of transcription factors and several putative signaling components were up-regulated by aluminum. Chloroplast structural and photosynthetic genes were, in general, down-regulated. A number of previously identified Al-responsive genes showed similar expression pattern changes in this study. For example, GST, Auxin-regulated, Peroxidase, and Chitinase, were found to be up-regulated by Al-stress, whereas, genes such as Wali 3 and Wali 4, were down-regulated. We also identified several up-regulated genes involved in vacuolar signaling, sorting and docking. Three genes were also up-regulated by Al-stress, Ras GTP-binding protein, ABC-cassette binding, and the AtELP1 receptor genes, have previously been documented as responsive to drought and/or oxidative stress and may play important roles the detoxification of Al ions by transportation and storage into root vacuoles. Ultrastructural changes in the roots tips cells of Arabidopsis were evaluated using TEM and EDXMA with SEM. Results using combined TEM and SEM-EDXMA showed that Al accumulattion in the root tip of Arabidopsis was detectable. The coupling these techniques can be useful for measuring Al in situ in cellular and sub cellular section of plant roots. Keywords: Stress response