Project description:Nontargeted and targeted metabolomics measurements of abiotic stress responses in three-week-old Arabidopsis thaliana plants' rosette leaf tissue for Col-0 wild type plants and double/triple knockout mutants of aquaporins (pip2;1 pip2;2 and pip2;1 pip2;2 pip2;4) treated with drought, heat at different air humidities, or combined drought-heat stress at different air humidities. This experiment contains FT-ICR-MS measurements for 103 Arabidopsis thaliana rosette leaf samples covering three genotypes under six different environmental conditions. The three genotypes comprise the Col-0 wildtype and two loss-of-function mutants of aquaporins, a pip2;1 pip2;2 double mutant and a pip2;1 pip2;2 pip2;4 triple mutant (respective AGI locus identifiers: AT3G53420, AT2G37170, AT5G60660). The six conditions include control condition (well-watered, 22 °C, 70% relative air humidity), drought stress (one week without watering), heat stress without changing the absolute humidity of the ambient air (6 hours at 33 °C, 37% relative air humidity), heat stress with supplemented air humidity to maintain a constant vapor pressure deficit before and during the heat episode (6 hours at 33 °C, 84% relative air humidity), and the combinations of drought pretreatment with each of the two heat stress variants (one week of drought followed by 6 hours of heat stress). Samples from all conditions were harvested at the same time (within 15 min starting at 5 pm). For validation, GC-TOF-MS measurements were done for two genotypes (wildtype, double mutant) and two conditions (drought, control) on partially overlapping samples.
Project description:Mitochondria play important roles in the plant stress responses and the detoxification of the reactive oxygen species generated in the electron-transport chain. Expression of genes encoding stress-related proteins such as the mitochondrial small heat shock proteins (M-sHSP) is upregulated in response to different abiotic stresses. In Arabidopsis thaliana, three M-sHSPs paralogous genes were identified, although their function under physiological conditions remains elusive. Here, we analyzed the phenotype, proteomic and metabolic profiles of the loss-of-function mutants of M-sHSPs (single, double and triple mutants) during normal plant growth. The triple mutant showed the most prominent altered phenotype at vegetative and reproductive stages without any externally applied stress. They displayed chlorotic leaves, growth arrest and low seed production. Concomitantly, they exhibited increased levels of sugars, free amino acids such as proline, citric and ascorbic acid, among other metabolites. Single and double mutants displayed intermediate phenotype suggesting a redundant function of these proteins. All single, double and triple mutants showed alteration of proteins involved in photosynthesis, mitochondrial metabolism and antioxidant defense compared to the wild-type plants. Overall, depletion of M-sHSPs causes severe impact in fundamental metabolic processes, localized in different cell compartments, leading to alterations in the correct plant growth and development.
Project description:Plant stress caused by pathogens or though abiotic means (e.g. drought or temperature) reduces agricultural yields, causing substantial economic losses while reducing food security at the global level. It is critical to recognize how plants perceive stress signals to elicit responses for survival. Endogenous plant peptidases and their peptide products play an important role in the signaling of plant immune processes. Thimet oligopeptidases (TOPs) are zinc-dependent peptide hydrolases with a conserved HEXXH active site motif. These metallopeptidases are critical components in plant response to oxidative stress triggered by pathogens or abiotic factors and are required for a fully functioning immune response to certain pathogens. Further characterization of plant TOPs and their peptide substrates would provide insights into their contribution to defense signaling, stress perception, and plant adaptation pathways. Herein, a quantitative mass spectrometry-based peptidomics approach was implemented to characterize the Arabidopsis thaliana plant peptidome and in the context TOPs (Fig. 1). A comparison between wild type (Col-0) and top1top2 null mutant revealed putative direct and indirect TOPs substrates in vivo.
Project description:Considering global climate changes, incidences of combined drought and heat stress are likely to increase in the future and will considerably influence plant-pathogen interactions. Until now, little is known about plants exposed to simultaneously occurring abiotic and biotic stresses. To shed some light on molecular plant responses to multiple stress factors, a versatile multi-factorial test system, allowing simultaneous application of heat, drought and virus stress, was developed. Comparative analysis of single, double and triple stress responses by transcriptome and metabolome analysis revealed that gene expression under multi-factorial stress is not predictable from single stress treatments. Hierarchical cluster and principal component analysis identified heat as the major stress factor clearly separating heat-stressed from non-heat stressed plants. We identified 11 genes differentially regulated in all stress combinations as well as 23 genes specifically-regulated under triple stress. Furthermore, we showed that virus treated plants displayed enhanced expression of defense genes, which was abolished in plants additionally subjected to heat and drought stress. Triple stress also reduced expression of genes involved in the R-mediated disease response and increased the cytoplasmic protein response which was not seen under single stress conditions. These observations suggested that abiotic stress factors significantly altered TuMV-specific signaling networks which lead to a deactivation of defense responses and a higher susceptibility of plants. Collectively, our transcriptome and metabolome data provide a powerful resource to study plant responses during multi-factorial stress and allows identifying metabolic processes and functional networks involved in tripartite interactions of plants with their environment.