Study On Regulation Of Calcium Uptake In M. Hupehensis Rehd. Roots And Characteristics Of Ca～(2+)-ATPase

The characteristics of calcium uptake, regulation of Ca2+uptake and Ca2+-ATPase by IBA,and correlation between Ca2+-ATPase and calcium contents in mature shoots were studied,using seedlings and two-year-old M. hupehensis Rehd. as materials under Hoagland nutrientsolution. The regulation mode of IBA to Ca2+uptake was researched from the signaltransduction aspect. The results were in followings: 1.When the Ca2+ concentration in nutrient solutions was in the range of 0.04~0.5mmol/L, the relationship between Ca2+-absorbing rate and Ca2+ concentration in seedlingsroots treated with or without IBA(100 μmol/L IBA)was coincident with Michaelis-Mentendynamics mode, while, when Ca2+ concentration was in the range of 0.5~4 mmol/L, therelationship between them could not be fitted by Michaelis-Menten equation. IBA increasedthe Ca2+-absorbing efficiency in roots. 2.External Ca2+ and culture time affects the Ca2+ uptake rate, calcium content in rootsand leaves of M. hupehensis. During the experiment, the extent of increased calcium contentin root, Ca2+uptake rate and calcium content in leaves reduced. In the nutrient solution with noCa2+, the calcium content in roots increased, which showed calcium in overground plantstransport down to roots. 3.Effect of IBA on Ca2+-absorbing in seedling roots varied with the Ca2+ concentrationand was also related to the cultured time. When seedlings were cultured in nutrient solutionwith 100 μmol/L IBA and 0.03 mmol/L Ca2+ for 3 days, the Ca2+-absorbing rate increased by31.7%; in the nutrient solution with 0.3 mmol/L Ca2+, the rate increased by 50%; in thenutrient solution with 3 mmol/L Ca2+, the rate increased by 17.3%. Compared to that ofcontrol, Ca2+-absorbing rate in treated seedlings usually increased after being treated for 12days. Cultured in Ca2+ concentration of 0.03 mmol/L, the Ca2+-absorbing rate in seedlingsroots was increased by 37.7% by 100 μmol/L IBA. The change value of absorb rate was not 4山东农业大学博士学位论文significantly different between in the middle and high Ca2+ concentration nutrient solutionswith increasing value of 80%. It suggested that 0.3 mmol/L Ca2+ and 100 μmol/L IBA play amutual increased role to Ca2+ uptake of roots. 4.In the nutrient solution without Ca2+, IBA increased the calcium contents in roots andleaves a little, 100μg/gDW and 48μg/gDW respectively. The calcium content in seedlingleaves cultured for 12 days was similar with that of cultured for 3 days, while the calciumcontent in seedling roots increased. IBA cannot influence the calcium content markedly. In the nutrient solution with 3 mmol/L Ca2+ and 100 μmol/L IBA, the calcium content inroot and leaves increased by 140% and 58% respectively. When cultured for 12 days, thecalcium content in roots and leaves were higher than that of cultured for 3 days. Comparedwith CK, IBA increased the calcium content in roots, reduced the calcium content in leaves.In this experiment, more calcium accumulated in roots when calcium content was 9.5mg/gDW. So, the effect of IBA on calcium absorb for seedlings was little. In the nutrient solution with 0.3 mmol/L Ca2+ and 100 μmol/L IBA, the calcium contentin roots and leaves had significant difference with that of in the solution without IBA. IBAincreased the calcium content in leaves, while reduced the calcium content in roots. Whencultured for 12 days, IBA had no effect on calcium content in leaves, but made the calciumcontent in roots fall. In the nutrient solution with 0.03 mmol/L Ca2+, compared with CK, IBA increased thecalcium content in seedling eaves and reduced the calcium content in roots of seedlingscultured for 3 days. The effect of IBA on calcium content in seedling roots and leaves wassimilar with on that of seedlings cultured for 12 days. IBA promoted calcium transportationfrom roots to overground parts, and had a better value to calcium absorb for seedlings inwhole. 5. The Ca2+-ATPase...