[Effects of grafting on cucumber leaf SOD and CAT gene expression and activities under low temperature stress]

This paper studied the relative expression of Mn-SOD, Cu/Zn-SOD and CAT mRNAs and the changes of SOD, Mn-SOD, Cu/Zn-SOD and CAT activities in grafted and own-rooted cucumber leaves under low temperature stress, and their relations with the cold resistance of cucumber. For both grafted and own-rooted cucumber leaves, the relative expression of Mn-SOD and Cu/Zn-SOD mRNAs under low temperature stress was respectively accordance with the changes of Mn-SOD and Cu/Zn-SOD activities, while the expression of CAT mRNA was not accordance with the change of CAT activity. The relative expression of Mn-SOD and Cu/Zn-SOD mRNAs and the activities of SOD, Mn-SOD and Cu/Zn-SOD in grafted cucumber leaves were higher than those in own-rooted cucumber leaves, while the MDA content and electrolytic leakage were in adverse. The higher SOD activity regulated by the higher SOD mRNAs expression in grafted cucumber leaves might be the key factor of grafted cucumber having a higher cold resistance to low temperature stress than own-rooted cucumber. The relative expression of CAT mRNA was slightly higher in functional leaves but lower in young leaves of grafted cucumber, while less difference was observed in CAT activity, comparing with own-rooted cucumber, which illustrated that low temperature stress had lesser effects on the relative expression of CAT mRNA and the activity of CAT in grafted cucumber leaves.