okadaic-acid and methyl-jasmonate

Following a stress event, jasmonate-dependent signaling pathway triggers a shift from growth to defense responses that are accompanied by the cessation of growth in many plants. However, the processes leading to this growth inhibition remain obscure. In this study, we provide evidence for a rapid inhibition of cell hydraulic conductivity (L

Topics: Acetates; Arabidopsis; Biological Transport; Cyclopentanes; Gene Expression Regulation, Plant; Okadaic Acid; Oxylipins; Water

MicroRNAs (miRNAs) are small noncoding RNAs which post-transcriptionally regulate gene expression by directing mRNA cleavage or translational inhibition. miRNAs play multiple roles in the growth, development and stress responses in plants. However, little is known of the wounding-responsive miRNAs and their regulation. Here, we investigated the expression patterns of microR828 (miR828) on wounding in sweet potato (Ipomoea batatas cv Tainung 57). The expression of miR828 was only detected in leaves, and was induced by wounding rather than by ethylene, hydrogen peroxide (H2O2), methyl jasmonate or nitric oxide (NO). Moreover, cyclic guanosine monophosphate (cGMP) was necessary for miR828 accumulation in leaves on wounding. Two miR828 target candidates, named IbMYB and IbTLD, were obtained by cDNA cloning, and their mRNA cleavage caused by miR828 was confirmed by cleavage site mapping, agro-infiltration and transgenics studies. The reduction in IbMYB and IbTLD expression coincided with the induction of miR828, demonstrating that IbMYB and IbTLD might be miR828 targets. Furthermore, transgenic sweet potato overexpressing miR828 precursor affected lignin and H2O2 contents. These results showed that cGMP could regulate wounding-responsive miR828, which repressed the expression of IbMYB and IbTLD. Subsequently, lignin and H2O2 were accumulated to participate in defense mechanisms.

Topics: Acetates; Agrobacterium; Antioxidants; Base Sequence; Calcium; Cyclic ADP-Ribose; Cyclic GMP; Cyclopentanes; Ethylenes; Gene Expression Profiling; Gene Expression Regulation, Plant; Hydrogen Peroxide; Ipomoea batatas; Lignin; MicroRNAs; Molecular Sequence Data; Niacinamide; Nitric Oxide; Okadaic Acid; Oxylipins; Phosphoprotein Phosphatases; Plant Proteins; Plants, Genetically Modified; Propanols; Protein Kinases; RNA, Messenger; Staurosporine; Stress, Mechanical

Methyl jasmonate (MeJA) induces stomatal closure similar to abscisic acid (ABA), and MeJA signaling in guard cells shares some signal components with ABA signaling. As part of this process, MeJA as well as ABA induce the elevation and oscillation of cytosolic free-calcium concentrations ([Ca(2+)](cyt)) in guard cells. While abscisic acid-induced [Ca(2+)](cyt) oscillation has been extensively studied, MeJA-induced [Ca(2+)](cyt) oscillation is less well understood. In this study, we investigated the effects of K252a (a broad-range protein kinase inhibitor) and okadaic acid (OA, a protein phosphatase 1 and 2A inhibitor) on MeJA-induced [Ca(2+)](cyt) oscillation in guard cells of Arabidopsis thaliana ecotype Columbia expressing the Ca(2+) reporter yellow cameleon 3.6. The protein kinase inhibitor K252a abolished MeJA-induced stomatal closure and reduced MeJA-elicited [Ca(2+)](cyt) oscillation. The protein phosphatase inhibitor OA, on the other hand, did not inhibit these processes. These results suggest that MeJA signaling involves activation of K252a-sensitive protein kinases upstream of [Ca(2+)](cyt) oscillation but not activation of an OA-sensitive protein phosphatase in guard cells of A. thaliana ecotype Columbia.

Topics: Abscisic Acid; Acetates; Arabidopsis; Arabidopsis Proteins; Calcium; Calcium Signaling; Carbazoles; Cyclopentanes; Enzyme Inhibitors; Indole Alkaloids; Okadaic Acid; Oxylipins; Phosphoprotein Phosphatases; Phosphorylation; Plant Stomata; Protein Kinases; Time Factors

Methyl jasmonate (MeJA) as well as abscisic acid (ABA) induces stomatal closure with their signal crosstalk. We investigated the function of a regulatory A subunit of protein phosphatase 2A, RCN1, in MeJA signaling. Both MeJA and ABA failed to induce stomatal closure in Arabidopsis rcn1 knockout mutants unlike in wild-type plants. Neither MeJA nor ABA induced reactive oxygen species (ROS) production and suppressed inward-rectifying potassium channel activities in rcn1 mutants but not in wild-type plants. These results suggest that RCN1 functions upstream of ROS production and downstream of the branch point of MeJA signaling and ABA signaling in Arabidopsis guard cells.

Topics: Abscisic Acid; Acetates; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Okadaic Acid; Oxylipins; Plant Stomata; Potassium Channels, Inwardly Rectifying; Protein Phosphatase 2; Reactive Oxygen Species; Signal Transduction

The lily PR-10 belongs to a family of intracellular pathogenesis-related (IPR) proteins. Genomic Southern analysis indicates that the PR-10 is encoded by a family of multiple genes. Seven heterogeneous cDNA clones encoding lily PR-10 from Lilium longiflorum are divided into two subclasses based on sequence comparison and Southern hybridization. A 82% overall sequence similarity was found between the two subclasses (represented by PR-10c and d). The two cDNAs include an open reading frame of 474 bp encoding 157 amino acids. 5'- and 3'-untranslated regions exhibit low similarity, but similarity is high in the coding region. The lily PR-10 genes are induced by abscisic acid (ABA) and methyl jasmonate (MeJA) in the anther and various other organs of lily plants. The induction of PR-10 genes by ABA and MeJA in lily anthers occurs by two separate signal transduction pathways. The protein phosphatase inhibitor okadaic acid inhibits the MeJA-induced expression of PR-10 genes downstream of MeJA. In addition, the protein kinase inhibitor staurosporine inhibits the MeJA-induced expression of PR-10 genes, implying that an activity of staurosporine-sensitive protein kinases exists downstream of MeJA in the anther. However, okadaic acid does not inhibit the ABA-induced expression of PR-10 genes whereas staurosporine does. These observations suggest that, in addition to the known pathway that ABA induces gene expression by activating JA or MeJA, a MeJA-independent pathway of ABA induction exists in the anther. The alternative pathway of ABA induction involves a staurosporine-sensitive protein kinase activity downstream of ABA.

Topics: Abscisic Acid; Acetates; Amino Acid Sequence; Base Sequence; Cloning, Molecular; Cyclopentanes; DNA, Complementary; Gene Expression Regulation, Plant; Glycoside Hydrolases; Liliaceae; Molecular Sequence Data; Multigene Family; Okadaic Acid; Oxylipins; Plant Proteins; Recombinant Proteins; Sequence Alignment; Sequence Homology, Amino Acid; Sequence Homology, Nucleic Acid; Signal Transduction; Transcription, Genetic