Study On Physiological And Biochemical Responses To Drought Stress And Low Temperature In Rose And SOD Gene Expression Under 4℃ Low Temperature

Using the main varieties in Yunnan province,Carola(red),Movie Star(pink)and Tineke(white)as thee xperimental materials,we researched the effects of drought stress and low temperatue(4℃)on the petals’ water content,soluble protein content,malondialdehyde(MDA)and superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),glutathione reductase(GR),ascorbate peroxidase(APX)activity.Then we used comprehensive subordinate function values to assess drought resistance and low temperature of eight representative peanut varieties.In our research,the expression characteristics of RhMnSOD,RhFeSOD1,RhCu/ZnSOD1,RhCu/ZnSOD2 and RhCu/ZnSOD3 gene in petals of carola rose under low temperature were analyzed by real-timePCR.The main findings are as follows:(1)Using the main rose cultivars in Yunnan province,Carola(red),Movie Star(pink)and Tineke(white)as the experimental materials,we researched the effects of drought stress on the petals’ relative moisture content,soluble protein content,membrane peroxidation and antioxidant enzymes’ activities.Our results showed that relative moisture contents and soluble protein of the pedals’ decreased during the drought stress.While the malondialdehyde(MDA)contents kept increasing and reached the peak at the fifth day and Tineke’s MDA contents were the highest.The activities of the petals’ superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)and glutathione reductase(GR),ascorbic acid peroxidase(APX)declined after rising.CAT,POD,APX and GR reached the maximum on the third day,which illustrated the petal cells had the highest abilities of removing reactive oxygen species(ROS).Then the pedals’ antioxidant capacity decreased sharply and the pedals began to senescence and die.The three roses’ APX activities did not decline significantly in the later period of drought stress,which indicated that APX played a more important role in drought resistance in the later treatment.The SOD activity of Corolla had the largest increase under the drought stress,and its average activity was also the highest among the three varieties.The POD activity of Corolla reached the maximum at the third day,which was 9.2 times of that of Tineke,indicating that the Corolla’s drought-tolerant was stronger.According to the average value of membership function,the drought resistance abilities of roses are sorted,following as: Corolla> Movie Star>Tineke.In conclusion,our results suggest that three kinds of rose cut flowers increase their drought-tolerant by increasing the activity of antioxidant enzymes and the degree of peroxidation of petal membranes is aggravated by drought stress,especially Corolla showed more resistant to drought.(2)Our results showed that contents of the petals’ soluble protein first decreased and then increased during the low temperature treatment.While the malondialdehyde(MDA)contents kept increasing and then tended to smooth after the third day.The activities of the petals’ superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)and glutathione reductase(GR),ascorbic acid peroxidase(APX)increased and then decreased,the activity of POD were in the highest activity during the treatment,which showed POD was the main enzyme of the responsed stress of the rose.The activity of Tineke’s POD was 8.54 times higher than that of the control group.The antioxidant enzyme system of the three fresh cut roses showed an obvious response to low temperature treatment,but the low temperature tolerance of different varieties were different.According to comprehensive subordinate function values,the drought resistance abilities of roses are sorted,following as: Tineke > Movie Star >Corolla.(3)The expression levels of RhMnSOD,RhFeSOD1,RhCu/ZnSOD1,RhCu/ZnSOD2 and RhCu/ZnSOD3 genes under low temperature treatment(4°C)were analyzed by real-time PCR.The results showed that the expression levels of RhFeSOD1,RhCu/ZnSOD2 and RhCu/ZnSOD3 were affected by low temperature treatment,and the gene expression decreased firstly and then increased.The expression of RhCu/ZnSOD1 decreased continuously,and the fifth day was only 0.468 times of the initial value,indicating that the expression was inhibited by low temperature.Althoungh the expression of RhMnSOD changed slightly during the treatment of low temperature which means that RhMnSOD was not a control gene responsity to low temperature.The experimental results show that RhCu/ZnSOD1,RhCu/ZnSOD2 and RhCu/ZnSOD3 are Cu/ZnSOD family genes,but they play different roles in different stresses.