In this study, the aim was to determine the effect of magnetic fi eld on peroxidase activities of soybean tissue culture. Shoot tips were put into petri dishes and exposed to a magnetic fi eld for a period of 2.2 and 19.8 s at a magnetic fl ux of 2.9-4.6 mT. The shoot and root formation rate, fresh weights, chlorophyll quantities, total RNA concentrations and peroxidase activities of regenerated shoots from control and treated shoot tips were determined. While the rate of shoot formation was 28.57% in the control group, this rate was increased to 94.33% and 78.18%, respectively, in the explants that were exposed to a magnetic fi eld for a period of 2.2 and 19.8 s. While the percentage of root formation in controls was 4.76%, this rate increased to 47.17% and 54.54%, respectively, in those that were exposed to a magnetic fi eld at the same periods. When the fresh weights were determined, we found that the fresh weights of plantlets regenerated from treated explants were increased relative to controls. Chlorophyll a, chlorophyll b and total chlorophyll contents increased 21%, 13% and 18%, respectively, relative to control groups at 2.2 s. Peroxidase activity signifi cantly increased in all magnetic fi eld treatments (p<0.05). The total RNA concentration of seedlings regenerated from treatment explants signifi cantly increased relative to controls (p<0.05). The regeneration and plant growth of shoot tips exposed to a magnetic fi eld with a 2.2 s period were positively affected by the MF and increased with respect to controls and the length of time exposed.

BackgroundThe aim of this study is to compare the tolerance mechanisms of two industrial tomato varieties (X5671R and 5MX12956) under drought stress. 14 days-old tomato seedlings were subjected to 7 days-long drought stress by withholding irrigation. The effects of stress were determined by enzymatic and non-enzymatic parameters. The physiological damages were evaluated via lipid peroxidation ratio, total protein content, relative water content, chlorophyll content and proline accumulation. Enzymatic responses were determined by biochemical analysis and electrophoresis of SOD, APX, POX and CAT enzymes.ResultsRelative water contents of X5671R and 5MX12956 varieties at 7th day of drought were decreased to 8.4 and 12.2%, respectively. Applied drought decreased all photosynthetic pigments of X5671R and 5MX12956 varieties during the treatment period significantly comparing to the Day 0 as the control. Total protein content, lipid peroxidation and proline accumulation presented increased values in both varieties in accordance with the increasing stress intensity. According to lipid peroxidation analysis, 5MX12956 tomato variety was found more drought sensitive than X5671R variety. Antioxidative enzyme activities showed increases in both varieties as a response to drought stress, although CAT and APX activities presented decrease on the 7th day of applied stress. 7 days long drought stress differentially altered POX, APX and SOD isozyme patterns. Same POX bands were observed in both varieties with different band intensities.ConclusionsHowever, main isozyme pattern differences were obtained for SOD and APX. APX1, Fe-SOD and Cu/Zn-SOD2 isozyme bands should be evaluated to define their main role in the tolerance mechanism of both tomato varieties.

No abstract

No abstract

No abstract