Project description:Plants engineered for abiotic stress tolerance may soon be commercialized. The engineering of these plants typically involves the manipulation of complex multigene networks and may therefore have a greater potential to introduce pleiotropic effects than the simple monogenic traits that currently dominate the plant biotechnology market. Drought- tolerant Arabidopsis thaliana were engineered through overexpression of the transcription factor ABF3 in order to investigate unintended pleiotropic effects. In order to eliminate position effects, the Cre/lox recombination system was used to create control plant lines that contain identical T-DNA insertion sites but with the ABF3 transgene excised. This additionally allowed us to determine if Cre recombinase can cause unintended effects that impact the transcriptome. Microarray analysis of control plant lines that underwent Cre-mediated excision of the ABF3 transgene revealed only two genes that were differentially expressed in more than one plant line, suggesting that the impact of Cre recombinase on the transcriptome was minimal. In the absence of drought stress, overexpression of ABF3 had no effect on the transcriptome, but following drought stress, differences were observed in the gene expression patterns of plants overexpressing ABF3 relative to control plants. Examination of the functional distribution of the differentially expressed genes revealed strong similarity indicating that unintended pathways were not activated. In response to drought stress, overexpression of ABF3 results in a reprogramming of the drought response, which is characterized by changes in the timing or strength of expression of some drought response genes, without activating any unexpected gene networks. These results illustrate that important gene networks are highly regulated in Arabidopsis and that engineering stress tolerance may not necessarily cause extensive changes to the transcriptome.
Project description:To improve both drought stress tolerance and growth of plants, we generated transgenic Arabidopsis plants that overexpress DREB1A and GA5. It was reported that DREB1A improves drought stress tolerance in various crops but causes dwarfism, and GA5 encodes a GA synthetic enzyme which enhances plant growth. We performed microarray experiments using a single overexpressor of GA5 and the double overexpressor of DREB1A and GA5 to study the potential interactions of the gene networks regulated by the two factors in the double overexpressor.
Project description:To improve both drought stress tolerance and growth of plants, we generated transgenic Arabidopsis plants that overexpress two transcription factors: DREB1A and PIF4. It was reported that DREB1A improves drought stress tolerance in various crops but causes dwarfism, and PIF4 enhances cell elongation through activation of cell wall synthesis. We performed microarray experiments using a single overexpressor of PIF4 and the double overexpressor of DREB1A and PIF4 to study the potential interactions of the gene networks regulated by the two transcription factors in the double overexpressor.
Project description:To improve both drought stress tolerance and growth of plants, we generated transgenic Arabidopsis plants that overexpress two transcription factors: DREB1A and OsPIL1. It was reported that DREB1A improves drought stress tolerance in various crops but causes dwarfism, and OsPIL1 enhances cell elongation through activation of cell wall synthesis in rice. We performed microarray experiments using a single overexpressor of OsPIL1 and the double overexpressor of DREB1A and OsPIL1 to study the potential interactions of the gene networks regulated by the two transcription factors in the double overexpressor.
Project description:Freshwater is a limited and dwindling global resource; therefore, efficient water use is required for food crops that have high water demands, such as rice, or for the production of sustainable energy biomass. We show here that expression of the Arabidopsis HARDY (HRD) gene in rice improves water use efficiency, the ratio of biomass produced to the water used, by enhancing photosynthetic assimilation and reducing transpiration. These drought tolerant low-water-consuming rice plants exhibit increased shoot biomass under well irrigated conditions and an adaptive increase in root biomass under drought stress. The HRD gene, an AP2/ERF-like transcription factor, identified by a gain-of-function Arabidopsis mutant hrd-D having roots with enhanced strength, branching, and cortical cells, exhibits drought resistance and salt tolerance, accompanied by an enhancement in the expression of abiotic stress associated genes. Although HRD overexpression in Arabidopsis produces thicker leaves with more chloroplast-bearing mesophyll cells, in rice there is an increase in leaf biomass and bundle sheath cells that probably contribute to the enhanced photosynthesis assimilation and efficiency. HRD overexpression was also studied for clues of molecular mechanisms involved using microarrays. The results exemplify application of a gene identified from the model plant Arabidopsis for the improvement of water use efficiency coincident with drought resistance in the crop plant rice. Keywords: Genetic modification transcription factor overexpression mutant
Project description:Drought is a major abiotic stress that threatens global food security. Circular RNAs (circRNAs) are endogenous RNAs. How these molecules influence plant stress responses remains elusive. Here, a large scale circRNA profiling identified 2174 and 1354 high-confidence circRNAs in maize and Arabidopsis, respectively, and most were differentially expressed in response to drought. A substantial number of drought-associated circRNA hosting genes were involved in conserved or species-specific pathways in drought responses. Comparative analysis revealed that circRNA biogenesis was more complex in maize than in Arabidopsis. In most cases, maize circRNAs were negatively correlated with sRNA accumulation. In 368 maize inbred lines, the circRNA-hosting genes were enriched for SNPs associated with circRNA expression and drought tolerance, implying either important roles of circRNAs in maize drought responses or their potential use as biomarkers for breeding drought-tolerant maize. Additionally, the expression levels of circRNAs derived from drought-responsible genes encoding calcium-dependent protein kinase and cytokinin oxidase/dehydrogenase were significantly associated with drought tolerance of maize seedlings. Specifically, Arabidopsis plants overexpressing circGORK (Guard cell outward-rectifying K+-channel) were hypersensitive to ABA, but insensitive to drought, suggesting a positive role of circGORK in drought tolerance. We report the transcriptomic profiling and transgenic studies of circRNAs in plant drought responses, and provide evidences highlighting the universal molecular mechanisms involved in plant drought tolerance.