Project description:Recently, 2-aminoxy-3-phenylpropionic acid (L-AOPP) had been demonstrated to possess an inhibitory activity against IAA biosynthesis but the molecular basis of the action was unclear. To investigate the function of L-AOPP, we conducted microarray analysis using the shoot apical meristem (SAM) part of A. thaliana in addition to whole plants after the treatment of L-AOPP. We performed microarray analysis using the shoot apical meristem (SAM) part of A. thaliana (Columbia-0) to investigate function of 2-aminoxy-3-phenylpropionic acid (L-AOPP) in relation to inhibition of auxin biosynthesis. Total RNA was extracted from SAM part of 7-day-old seedlings grown on 1/2 MS medium containing L-AOPP (50 µM),L-AOPP (50 µM) + Indole-3-acetic acid (IAA 10 nM) or Dimethyl sulfoxide (DMSO 0.1%).
Project description:Recently, 2-aminoxy-3-phenylpropionic acid (L-AOPP) had been demonstrated to possess an inhibitory activity against IAA biosynthesis but the molecular basis of the action was unclear. To investigate the function of L-AOPP in relation to Auxin biosynthesis, we conducted microarray analysis.
Project description:Recently, 2-aminoxy-3-phenylpropionic acid (L-AOPP) had been demonstrated to possess an inhibitory activity against IAA biosynthesis but the molecular basis of the action was unclear. To investigate the function of L-AOPP, we conducted microarray analysis using the shoot apical meristem (SAM) part of A. thaliana in addition to whole plants after the treatment of L-AOPP.
Project description:Ethylene induced hyponastic growth in Arabidopsis thaliana F.F. Millenaar L.A.C.J. Voesenek and A.J.M. Peeters Our aim is to identify genes involved in the ethylene induced hyponastic growth. Upon submergence some plant species like Rumex palustris changes its leaf angle (hyponastic growth) and shows enhanced petiole elongation to reach the water surface. In Rumex palustris the hyponastic growth is initiated by an increased concentration of ethylene due to physical entrapment and ongoing ethylene biosynthesis. A proteomics, genomics and genetical approach to improve our understanding of above described flooding-induced responses are not feasible in Rumex palustris since genomic information about this species is limited. However it is possible to use the model plant Arabidopsis thaliana as a tool in flooding research. Natural accessions (Be0 Col Cvi Kas Ler Nd Rld Shah and Ws) show considerable genetic variation in hyponastic growth upon exposure to ethylene Col exhibiting the largest effect (maximum rate after 3 hours) and Ler no effect whatsoever. Using a computer controlled digital camera the hyponastic growth is measured in great detail. Next to ethylene addition also a transfer to low light causes hyponastic growth. This seems to be an ethylene independent pathway because etr1 and ctr1 showed hyponastic growth after transfer to low light. Ethylene and low light showed additive effects in Col. It is likely that ethylene induces more changes in gene expression than only the ones involved in hyponastic growth. By subtracting changes in the Ler expression profile from changes in the Col expression profile we expect to find why Col and Ler respond differently on ethylene by finding specific ethylene induced genes that are involved in hyponastic growth. The expression profile of Col following transfer to low light will be substracted from Col following ethylene addition to distinguish between genes that are involved in hyponastic growth but are not specific for ethylene induced hyponastic growth. There are strong indications in Rumex palustris that other hormones i.e. auxin ABAand GA are involved in the ethylene induced hyponastic growth. Currently mutants in ethylene auxin and ABA biosynthesis and/or signal transduction are screened for hyponastic growth. Preliminary results showed that also in Arabidopsis these other hormones are involved in ethylene induced hyponastic growth. Beside the mutant approach we also started a proteomics and a PCR based differential screen approach. Together with the proposed transcriptome analysis we hope to find new genes involved in ethylene induced hyponastic growth.
Project description:Somatic embryogenesis (SE) exemplifies the unique developmental plasticity of plant cells. The regulatory processes, including epigenetic modifications controlling embryogenic reprogramming of cell transcriptome, have just started to be revealed. To identify the genes of histone acetylation-regulated expression in SE, we analyzed global transcriptomes of Arabidopsis explants undergoing embryogenic induction in response to treatment with histone deacetylase inhibitor, trichostatin A (TSA). The TSA-induced and auxin (2,4-dichlorophenoxyacetic acid; 2,4-D)-induced transcriptomes were compared. RNA-seq results revealed the similarities of the TSA- and auxin-induced transcriptomic responses that involve extensive deregulation, mostly repression, of the majority of genes. Within the differentially expressed genes (DEGs), we identified the master regulators (transcription factors TF) of SE, genes involved in biosynthesis, signaling, and polar transport of auxin and NITRILASE-encoding genes of the function in indole-3-acetic acid (IAA) biosynthesis. TSA-upregulated TF genes of essential functions in auxin-induced SE, included LEC1/LEC2, FUS3, AGL15, MYB118, PHB, PHV, PLTs, and WUS/WOXs. The TSA-induced transcriptome revealed also extensive upregulation of stress-related genes, including those related to stress hormone biosynthesis. In line with transcriptomic data, TSA-induced explants accumulated salicylic acid (SA) and abscisic acid (ABA), suggesting the role of histone acetylation (Hac) in regulating stress hormone-related responses during SE induction. Since mostly the adaxial side of cotyledon explant contributes to SE induction, we also identified organ polarity-related genes responding to TSA treatment, including AIL7/PLT7, RGE1, LBD18, 40, HB32, CBF1, and ULT2. Analysis of the relevant mutants supported the role of polarity-related genes in SE induction. The study results provide a step forward in deciphering the epigenetic network controlling embryogenic transition in somatic cells of plants.
Project description:Proper functioning of the nuclear auxin pathway is essential for regulating plant growth and development by maintaining auxin homeostasis. To understand better physiological mechanisms involved in auxin signaling pathways we investigated the localization and effect of accumulation of auxin coreceptor IAA17/AXR3 in root. We demonstrate that the accumulation of stable nuclear AXR3-1 protein interferes with auxin homeostasis, causing auxin insensitivity and increased rapid root cell elongation followed by detained growth. This growth pattern is associated with changes in phytohormone gene expression. Data from transcriptomic screen combined with reporter lines and mutant studies declare essential role of auxin homeostasis in maintaining optimal root growth rate and development. We proposed a model in which rapid cell elongation is caused by combination of AXR3-1-dependent auxin insensitivity associated with unblocked gibberellin effect on root. This study demonstrate that plants coordinate gibberellin homeostasis by the auxin signaling pathway, contributing to avoid excessive root elongation.