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Prohydrojasmon (PDJ), a synthetic derivative of the plant hormone jasmonic acid, has been identified as a plant growth regulator used in various fruit and rice seedlings. In this study, we demonstrate the inhibition of transpiration by PDJ in the indica rice cultivar cv. Takanari compared with commercially available microcrystalline and paraffin wax agents in a greenhouse. Microcrystalline and paraffin wax agents inhibited approximately 30%–50% transpiration 3 h after application, and the inhibition lasted for seven days after treatment, depending on the concentration and the agent used. In contrast, PDJ inhibited approximately 40%–80% transpiration compared with control 0.5 h after treatment, and the effect lasted for one day. However, the effect almost disappeared 7 days after treatment. Thus, PDJ affects transpiration differently than commercially available products and could be used to lower excess transpiration in rice, specifically when an early, transient, and reversible inhibition is needed. [ABSTRACT FROM AUTHOR]

Prohydrojasmon (PDJ) is a synthetic derivative of the plant hormone jasmonic acid (JA), which is used in apples, grapes, and mandarin oranges as a plant growth regulator. Here, we show that irrigation of PDJ could prevent spindly growth of rice seedlings in both indica and japonica cultivars. PDJ also inhibited root elongation in hydroponically growing seedlings in various cultivars. The higher dry root weight following PDJ application than the controls was observed in two japonica cultivars. Furthermore, its reduction was slight in comparison with the inhibition of root elongation. Starch degradation in the endosperm of seedlings grown in PDJ solution was slower than those grown in the control. The inhibition of root elongation could be mediated by the combined application of PDJ and appropriate concentrations of a synthetic auxin, NAA (1-Naphthaleneacetic acid). Additionally, we generated transgenic rice carrying sGFP driven by the PBZ1 promoter, a marker gene for abiotic and biotic stress responses. The expression of PBZ1p::sGFP was induced by PDJ treatment in the roots and seeds. PDJ could be used as a plant growth regulator to prevent spindly growth and to induce stress responses in rice seedlings. [ABSTRACT FROM AUTHOR]

Background: Reactive oxygen species (ROS) production is an early event in the immune response of plants. ROS production affects the redox-based modification of cysteine residues in redox proteins, which contribute to protein functions such as enzymatic activity, protein-protein interactions, oligomerization, and intracellular localization. Thus, the sensitivity of cysteine residues to changes in the cellular redox status is critical to the immune response of plants., Methods: We used disulfide proteomics to identify immune response-related redox proteins. Total protein was extracted from rice cultured cells expressing constitutively active or dominant-negative OsRacl, which is a key regulator of the immune response in rice, and from rice cultured cells that were treated with probenazole, which is an activator of the plant immune response, in the presence of the thiol group-specific fluorescent probe monobromobimane (mBBr), which was a tag for reduced proteins in a differential display two-dimensional gel electrophoresis. The mBBr fluorescence was detected by using a charge-coupled device system, and total protein spots were detected using Coomassie brilliant blue staining. Both of the protein spots were analyzed by gel image software and identified using MS spectrometry. The possible disulfide bonds were identified using the disulfide bond prediction software. Subcellular localization and bimolecular fluorescence complementation analysis were performed in one of the identified proteins: Oryza sativa cold shock protein 2 (OsCSP2)., Results: We identified seven proteins carrying potential redox-sensitive cysteine residues. Two proteins of them were oxidized in cultured cells expressing DN-OsRac1, which indicates that these two proteins would be inactivated through the inhibition of OsRac1 signaling pathway. One of the two oxidized proteins, OsCSP2, contains 197 amino acid residues and six cysteine residues. Site-directed mutagenesis of these cysteine residues revealed that a Cys 140 mutation causes mislocalization of a green fluorescent protein fusion protein in the root cells of rice. Bimolecular fluorescence complementation analysis revealed that OsCSP2 is localized in the nucleus as a homo dimer in rice root cells., Conclusions: The findings of the study indicate that redox-sensitive cysteine modification would contribute to the immune response in rice.