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:In this study, we performed a large-scale leaf phosphoproteomic analysis of two wheat genotypes HX10 and NC47 to explore the complex protein phosphorylation network of signaling and regulatory events affecting rapid vegetative growth in wheat. We used TiO2 affinity chromatography combined with LC-MS/MS and Maxquant software to identify phosphopeptides and phosphorylated sites. Finally, 2,336 phosphopeptides containing 2,734 phosphorylation sites were identified from the two wheat genotypes HX10 and NC47 in our study.
Project description:The subsistence of terrestrial plants depends upon the ability of roots to absorb water and nutrients from the soil. Directed growth of the primary root from a layer of the soil with low water content towards a zone with high water content is known as hydrotropism. This tropic response enables the root to reach soil with the proper humidity for plant growth, and therefore avoid drought conditions. Although the shortage of sufficient water is the single-most critical factor affecting world agriculture, there are very few studies on hydrotropism in crop plants. The strength of the hydrotropic response (angle of curvature) of the maize primary root in maize varies enormously. After phenotyping root hydrotropism in 231 Drought Tolerant Maize for Africa hybrids, we performed a Genome Wide Association Study and found two candidate genes that regulate the ubiquitin/26 proteasome system. We also compared the root transcriptomes between maize accessions with contrasting hydrotropic response after 6 h of hydro stimulation: (CML376<2/NVOL46)-74-1-1-B) (robust response) and (CML376<2/SNL17)-28-1-1-B) (weak response). This analysis revealed that hydrotropism in maize seems to be regulated by chaperones, heat shock proteins, late embryogenesis abundant proteins, and ubiquitin ligases. Furthermore, we biochemically examined the role of protein ubiquitination and protein degradation during hydrotropism. Our results suggest that the signal transduction pathways induced by hydro stimulation in maize are like those triggered by heat, water stress, and protein ubiquitination.