The Effect Of Nodulation On The Plasma Membrane Ca～(2+) -ATPase From Tobacco Cell

The regenerated tobacco K326 plantlets were disposed in four different culture conditions:(R+D) 0.3mg/L 2,4-D and 5×108/L rhizobium;(R) 5×108/L rhizobium ; (D) 0.3mg/L 2,4-D; (CK) native Jesen Non-nitrogen medium.Tobacco treated with rhizobium alone grew most well among the four tested groups. Tobacco only treated with 2, 4-D appeared to be hurted. It had the character of dwarfish stem, yellow and smallish leaves and fake root. It is obvious that 2,4-D alone does harm to the growth of tobacco, but rhizobium alone can benefit to the growth of tobacco.Effect of 2,4-D , rhizobium on the plasma membrane Ca2+-ATPase from tobacco leaf ,stem and root were respectively tested . And effect of the paranoduled on the plasma membrane Ca2+-ATPase activity from tobacco root,stem and leaf were also tested. These results indicatedthat 2,4-D could increase the activity of the plasma membrane Ca2+-ATPase from root,stem and leaf in the period of 1-3 weeks. The activities of the plasma membrane Ca2t-ATPase from root,stem and leaf of the tobacco which treated with 2, 4-D and rhizobium were higher than those of tobacco only treated with native Jesen Non-nitrogen medium . From the result, we thought that 2, 4-D could induce tobacco to grow Paranodule and in this course of nodulation maybe involve Ca2+ signal transduction, and the plasma membrane Ca2+-ATPase played an important role in this course.Activities of the plasma membrane Ca2+-ATPase from tobacco leaf and root were determined and their Characterizations were also compared. The results indicated they were different in many aspects. The activity of leaf plasma memberan Ca2+-ATPase reached the maximum at pH 7. 0 and the root plasma membrane Ca2+-ATPase reached that at pH 6.0 and the latter showed a high activity in a broader range of pH, while the former activated in a narrower range of pH. In the range of pH tested, the activities of the root plasma membrane Ca2+-ATPase all were beyond 50%, if the activities of the leaf plasma membrane Ca-ATPase were beyond 50%, they must be in the range of pH 5.5~8. The optimum reaction temprature of the leaf plasma membrane Ca2+-ATPase was 45 C and that of the root plasma membrane Ca2+-ATPase was 40C. Even if the reaction temperature was between 50C and 55C, the activity of the leaf plasma membrane Ca-ATPase still was higher . The [ATP]0.5 of the leaf and root plasma membrane Ca2+-ATPase were 2. 2 mmol/L and 1.9 mmol/L respectively, their Hill coefficient for ATP were beyond 1.0, revealing an obvious positive cooperativity. The leaf and the root plasma membrane Ca2+-ATPase were activated by Ca2+, their Hill coefficient for Ca2+ were less than 1.0, suggesting a negative cooperativity. EB (Erythrosin B) could strongly inhibit theactivities of the leaf and root plasma membrane Ca2+-ATPase, and it had shown an obvious inhibition on both at 10umol/L With the increasing of the concentration of EB, the inhabition also gradually increased, only after its concentration reached 50 umol/L, the increase of inhabition of it was not remarkable. The [EB]0.5 of both were 18 umol/L and 21 umol/L respectively, indicating the tolerance of the latter was better than that of the former. The difference of the characterization of the plasma membrane Ca2+-ATPase from tobacco leaf and root and their relations with environment were discussed in this paper.