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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]