Induction Resistance Against Botiytis Cinerea In Cucumber By Trans-2-Hexenal

trans-2-Hexenal is one of the C6green leaf volatiles (GLVs). trans-2-Hexenal couldinhabit pathogenic fungi and bacteria growth and is also an intercommunion signal molecularenhancing disease resistance gene expression in plant self or neibor. It plays an important rolein arousing plant disease resistance responces. It had been reported that exogenoustrans-2-hxenal could induce disease resistace against phytopathogenic fungi in Arabidopsis.However, it hadn’t been reported whether trans-2-hexenal could induce resistance to Botrytiscinerea in cucumber and possible mechanism involved. In this paper, we examined theinduction activity of trans-2-hexenal against B. cinerea in cucumber seedling and combinedphytochemical, molecular and proteomics approaches to elucidate possible mechanismsinvolved. The mainly results are as follows:1. When cucumber leaves were pretreated with trans-2-hexenal and then inoculated withB. cinerea, we observed a45.13%reduction in lesions compared to the control. The resultindicated that trans-2-hexenal could induce protection of the cucumbers against gray moldcaused by B. cinerea.2. We studied the effects of trans-2-hexenal on some physiological and biochemicalcharacteristics in the cucumber seedings. The results showed that the amount of lignin intreated leaves increased significantly after treated for24h with trans-2-hexenal and was45.16%higher than control leaves. The activity of POD, PAL, PPO and LOX, fourdefense-related enzymes, were increased significantly with processing time extension. Aftertreatment36h, the defense-related enzymes activity increased53.49%,151.02%,29.88%and62.93%respectively. However, PAGE results exhibited that trans-2-hexenal did notinduce new generation of either PPO or POD isoenzymes.3. Exposure to trans-2-hexenal did not result in major increases in the transcript levels forPR-1and PR-2. However, the transcripts for PAL and PR-3were apparently higher than thoseof control plants and up-regulated4.65and9.57times respectively. The results showed thatthe induction pattern maybe similar to methyl jasmonate.4. The effect of trans-2-hexenal on leaf proteome was investigated by two-dimensionalgel electrophoresis. Compared with control seedlings, the treated plants produced16special protein spots,10unexpressed protein spots,17up-regulated higher than triple protein spotsand5down-regulated lower than triple protein spots. We analyzed32proteins throughMALDI-TOF mass spectrometry, and22proteins were tested, of which18proteins wereclearly identificated. Four proteins, LOX-9, Lectin, Sentrin/sumo-specific protease andProtein kinase are related with disease resistance. trans-2-Hexenal could also affectedphotosynthesis and energy metabolism related proteins. So, trans-2-hexenal inducedresistance might have to do with these differentially expressed proteins.