| Trans-β-ocimene is an important plant communication signal molecule. It has been reported that trans-p-ocimene can induce simultaneous expression of SA maker gene PR1and JA/ET maker gene PDF1.2, suggesting antagonism between SA and JA/ET can be disarmed by ocimene. However, the mechanism of simultaneous expression of PR1and PDF1.2remains unclear. To elucidate the signaling mechanism of ocimene, biological experiments, genetics, molecular biological methodologies were employed in this study. The results were shown as below:1. The expression pattern of marker genes PR1, PDF1.2induced by ocimene was investigated. The maximum level of PR1and PDF1.2was induced by ocimene at10μM and7.5μM respectively.2. Application of exogenous trans-β-ocimene could increase Arabidopsis resistance against bacterial pathogen. Comparative analysis of symptoms developed post inoculation of Pseudomonas syringae DC3000in Arabidopsis ecotype Col-0revealed that resistance of plants treated by ocimene was elevated dramatically in comparison to those untreated, which suggested ocimene could enhance plant resistance.3. Signaling of ocimene involved transcription factor WTO and cofactor NPR1. Via real-time PCR assay, PR1expression profile was analyzed in npr1and wto treated with ocimene and MeSA respectively. The results showed that PR1level was undetectable in either npr1or wto treated with ocimene; however, PR1was elevated by MeSA in wto while no PR1transcripts were detected in npr1, suggesting WTO was a dispensable component in S A pathway.4. NPR1and WTO could interact physically. Via yeast-two hybrid, NPR1and WTO were proved to interact mutually for the first time, further suggesting interaction between NPR1and WTO was required for initiation of PR1expression.5. The critical concentration of ocimene to retain germination was determined, which underlying subsequent forward genetical methodologies to search components located in ocimene pathway and mapping the corresponding genes. |
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