The Stimulative Effect of Water Stress on the Plasma Membrane ATPase Activity in the Growing Zone of Maize Leaves
The Stimulative Effect of Water Stress on the Plasma Membrane ATPase Activity in the Growing Zone of Maize Leaves
复制标题
DOI：
--
复制
发表时间：
1993
期刊：
影响因子：
--
通讯作者：
H. Zhang
中科院分区：
文献类型：
--
作者：
H. Zhang
玉米幼苗根部用抗渗电位为-0. 4 MPa处理24 h，第5叶生长区H~+挤出速率显著增加。Na_3VO_4几乎完全抑制H~+的增加。0. 1 mmol/L（表1）。由此推测，H~+分泌的增加可能是水分胁迫引起质膜ATP酶活性增加的结果。玉米幼苗叶片生长区质膜（PM）经水相分离纯化后，具有ATP酶活性，最适pH为6。5（图1），并强烈抑制钒。K~+和Na~+对该酶活性有明显的促进作用。水分胁迫处理使质膜ATP酶活性提高1。5倍（表2），使质膜ATP酶的K_m从0. 33 mmol/L降至0. 11 mmol/L（表3，图3）。结果表明，水分胁迫处理提高了质膜ATP酶对底物ATP的亲和力，(max)从0上升。35 μ mol mg ~1 min 1至0.在不同水分胁迫条件下，玉米幼苗根系质膜中磷脂与蛋白质的比例发生变化。ATP酶活性在比值为1时最高。05（图5）。用0. 1 mmol/L对质膜ATP酶活性无明显影响，甚至略有增加。结果表明，部分干扰质膜ATP酶活性的蛋白质已从质膜上清除。
After the roots of intact maizeseedling were treated with PEGHoagland's solution with an osmoticpotential of -- 0. 4 MPa for 24 h, therate of H~+ extrusion increased marked-ly in thc growing zone of thc 5thleaves. The increase of H~+ was almostcompletely inhibited by Na_3VO_4. 0. 1mmol/L (Table 1). It Has been sug-gested that the increase of the H~+ ex-trusion may be the result of plasmamembranc ATPase acitvity increasecaused bv water stress. Plasma membrane (PM ), Puri-fied by two phase partition with aque-ous polymer from growing zone ofmaize seedling leaves, possessed theATPase activity with an optimum pHof 6. 5 (Fig. 1) and was strongly in-hibited by vanadate. K~+ and Na~+stimulatcd its activity markedly (Fig.2). Water stress treatment increasedplasma membrane ATPase activity by1. 5 times (Table 2), and decreasedthe K_m of PM ATPase from 0. 33mmol/L to 0. 11 mmol/L (Table 3,Fig. 3). It was showed that waterstress treatment increased the affinityof PM ATPase for substrate ATP, and?_(max) rose from 0. 35 umol mg ~1 min 1to 0. 87 umol mg~(-1) min~(-1) (Table 3).When the roots of intact maize seedlingwere treated by different water stress-es, the ratio of phospholipids to pro-teins in PM changed (Fig. 4). TheATPase had the maximun activitywhen the ratio was 1. 05 (Fig. 5). The treatment with cycloheximideat 0. 1 mmol/L did not decrease thePM ATPase activity, even increased itslightly (Table 4). It was suggestedthat some protein which interfered inPM ATPase activity had been removedfrom plasma membranes.