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:Transcriptional profiling after inhibition of cellulose synthesis by thaxtomin A and isoxaben in Arabidopsis thaliana suspension cells Perturbations in the cellulose content of the plant cell wall lead to global modifications in cellular homeostasis, as seen in cellulose synthase mutants or after inhibiting cellulose synthesis. In particular, application of inhibitors of cellulose synthesis such as thaxtomin A (TA) and isoxaben (IXB) initiates a programmed cell death (PCD) in Arabidopsis thaliana suspension cells that is dependent on de novo gene transcription. To further understand how TA and IXB activate PCD, a whole genome microarray analysis was performed on mRNA isolated from Arabidopsis suspension cells exposed to TA and IXB. More than 75% of the genes upregulated by TA were also upregulated by IXB, including genes encoding cell wall-related and calcium-binding proteins, defence/stress-related transcription factors, signalling components and cell death-related proteins. Comparisons with published transcriptional analyses revealed an important subset of genes generally induced in response to various biotic and abiotic stress.
Project description:CRABS CLAW (CRC) encodes a transcription factor of the plant-specific YABBY class in the model plant Arabidopsis thaliana. This gene is highly expressed in the abaxial (external) domain of the gynoecium wall and contributes to the establishment of abaxial-adaxial (external-internal) polarity in that tissue. Here we derive a list of putative target genes of CRC, which include AUXIN RESPONSE FACTOR4 (ARF4) and ASSYMETRIC LEAVES1 (AS1), both of which are known to be involved in the establishment of abaxial-adaxial polarity in lateral organs. ETTIN (ETT), which is partially redundant with ARF4, was not identified as a direct target of CRC, and this observation led us to predict that crc/ett double mutants might resemble ett/arf4 double mutants, which show a very strong breakdown of abaxial-adaxial polarity in the gynoecium wall. We have confirmed this prediction by constructing double mutants using several available mutant alleles of crc, ett and arf4. Interestingly, AS1 plays a role in the establishment of adaxial tissue identity in lateral organs, though its expression is not restricted to the adaxial domain. The observed positive regulation of AS1 by CRC may thus occur very early in gynoecium development, before CRC expression becomes polarised, or at later stages of development, specifically in the abaxial domain.
Project description:Heterotrimeric G proteins mediate crucial and diverse signaling pathways in eukaryotes. To gain insights into the regulatory modes of the G protein and the co-regulatory modes of the G protein and the stress hormone abscisic acid (ABA), we generated and analyzed gene expression in G protein subunit single and double mutants of the model plant Arabidopsis thaliana. Through a Boolean modeling approach, our analysis reveals novel modes of heterotrimeric G protein action. Keywords: transcriptome analysis; G protein subunit mutants; abscisic acid (ABA)