Swanson S. J., Jones R. L.
Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, California 94720-3102.
Plant Cell. 1996 Dec;8(12):2211-2221. doi: 10.1105/tpc.8.12.2211.
The roles of gibberellic acid (GA3) and abscisic acid (ABA) in the regulation of vacuolar pH (pHv) in aleurone cells of barley were investigated using the pH-sensitive fluorescent dye 2[prime],7[prime]-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). BCECF accumulated in vacuoles of aleurone cells, but sequestration of the dye did not affect its sensitivity to pH. BCECF-loaded aleurone cells retained their ability to respond to both GA3 and ABA. The pHv of freshly isolated aleurone cells is 6.6, but after incubation in GA3, the pHv fell to 5.8. The pHv of cells not incubated in hormones or in the presence of ABA showed little or no acidification. The aleurone tonoplast contains both vacuolar ATPase and vacuolar pyrophosphatase, but the levels of pump proteins were not affected by incubation in the presence or absence of hormones. We conclude that GA3 affects the pHv in aleurone cells by altering the activities of tonoplast H+ pumps but not the amounts of pump proteins.
利用pH敏感荧光染料2′,7′-双(2-羧乙基)-5(6)-羧基荧光素（BCECF），研究了赤霉素（GA3）和脱落酸（ABA）在调节大麦糊粉层细胞液泡pH（pHv）中的作用。BCECF积累在糊粉层细胞的液泡中，但染料的隔离并不影响其对pH的敏感性。加载了BCECF的糊粉层细胞保留了对GA3和ABA的响应能力。刚分离的糊粉层细胞的pHv为6.6，但在GA3中孵育后，pHv降至5.8。未在激素中孵育或在ABA存在下的细胞的pHv几乎没有酸化或没有酸化。糊粉层液泡膜同时含有液泡ATP酶和液泡焦磷酸酶，但在有或没有激素存在的情况下孵育，泵蛋白的水平不受影响。我们得出结论，GA3通过改变液泡膜H+泵的活性而非泵蛋白的量来影响糊粉层细胞的pHv。
