摘要
对耐低钾和不耐低钾的水稻（ＯｒｙｚａｓａｔｉｖａＬ．）“威优４９”和“远诱１号”的根原生质膜ＡＴＰａｓｅ性质的研究表明，这两种水稻的质膜ＡＴＰａｓｅ活性的最适ｐＨ均为６０，均在底物ＡＴＰ浓度为３ｍｍｏｌ／Ｌ时达到最大反应速度，Ｋｍ值均在０．８５左右。Ｋ＋对这两种水稻的质膜ＡＴＰａｓｅ活性均具有促进作用。当介质中［Ｋｍ］≤５０ｍｍｏｌ／Ｌ时随［Ｋ＋］的增大，对耐低钾品种根质膜ＡＴＰａｓｅ活性的促进作用明显大于不耐低钾品种；当介质［Ｋ＋］在１００～２００ｍｍｏｌ／Ｌ之间时，Ｋ＋对两种水稻品种质膜ＡＴＰａｓｅ活性的刺激效应的差别减小。这两个水稻品种的基础Ｈ＋分泌没有明显差别，但钾刺激的Ｈ＋分泌存在差异，Ｋ＋对耐低钾品种Ｈ＋分泌的刺激效应大于不耐低钾品种。抑制剂实验表明在耐低钾和不耐低钾的水稻品种中，Ｋ＋刺激的根质膜ＡＴＰａｓｅ活性，Ｋ＋刺激的Ｈ＋分泌和Ｋ＋吸收之间存在着紧密的联系。对Ｋ＋刺激的质膜ＡＴＰａｓｅ活性和Ｈ＋分泌的抑制会减少根对Ｋ＋的吸收量。推测耐低钾水稻的质膜ＡＴＰａｓｅ和Ｈ＋分泌对Ｋ＋更为敏感，特别是在低浓度Ｋ＋存在时，可能是耐低钾水稻更能利用低浓度Ｋ＋、在低钾环境中能更好生长的一个原因。
The characteristics of root plasma membrane ATPase (PMATPase) of “Weiyou 49”,a K+deficit tolerant rice (Oryza sativa L.) variety and of “Yuanyou 1”, a K+deficit nontolerant rice variety, had some similarities:Their optimum pH value were both about 6.0; Their activities reached the maximum at ATP concentration of 3 mmol/L; Km was 0.85 mmol/L and external K+ stimulated their activities. However, when was less than or equal to 50 mmol/L in the medium, the increasing of K+ stimulated the activity of the PMATPase of “Weiyou 49” much more than that of “Yuanyou 1”. When was between 100 to 200 mmol/L, the difference of the PMATPase activities decreased between the two rice varieties caused by K+ stimulation. The basic H+ extrusion of the two varieties had no apparent difference, but the H+ extrusion stimulated by K+ was different. The H+ extrusion of “Weiyou 49” was relatively more sensitive to external K+. The experiment using inhibitors showed that there were close relationship between the PMATPase activities stimulated by K+ and K+ uptake in the two varieties. The inhibition of PMATPase activity and H+extrusion stimulated by K+ reduced the K+ uptake of the root segments in both varieties. So the possible reason for “Weiyou 49” growing well in the low external K+ was that its PMATPase and H+ extrusion was more sensitive to external K+, especially when was low.
基金
国家自然科学基金
关键词
质膜ATPase
H^+分泌
K^+吸收
耐低钾
水稻
Plasma membrane ATPase, H+ extrusion, K+ uptake, K+_deficit tolerant rice variety
