Gilroy S, Jones R L
Department of Plant Biology, University of California, Berkeley 94720.
Proc Natl Acad Sci U S A. 1992 Apr 15;89(8):3591-5. doi: 10.1073/pnas.89.8.3591.
The effects of gibberellic acid (GA3) and abscisic acid (ABA) on the temporal and spatial dynamics of cytosolic calcium concentration ([Ca2+]i) in aleurone protoplasts of barley (Hordeum vulgare L. cv. Himalaya) were measured by using fluorescence ratio analysis and confocal microscopy. After 4-6 h of treatment, GA3 induced a sustained increase in [Ca2+]i from 50 to 150 nM in aleurone protoplasts. The increase in [Ca2+]i preceded the GA3-induced increase in alpha-amylase synthesis and secretion by 4 h. The elevation of [Ca2+]i was highest in the peripheral cytoplasm and may play a role in coordinating the secretory events there. Reducing Ca2+ levels in the incubation medium to below 500 microM inhibited the increase in [Ca2+]i and the GA3-induced stimulation of alpha-amylase synthesis and secretion. These data suggest that GA3 may increase [Ca2+]i by increasing the influx of Ca2+ at the plasma membrane. ABA reversed the effect of GA3 on [Ca2+]i within 3 h, 2 h before its effect on alpha-amylase production could be detected. Thus changes in [Ca2+]i may play a role in mediating the effects of GA3 and ABA on the synthesis and secretion of alpha-amylase in the aleurone cell.
通过荧光比率分析和共聚焦显微镜，测定了赤霉素（GA3）和脱落酸（ABA）对大麦（Hordeum vulgare L. cv. Himalaya）糊粉层原生质体胞质钙浓度（[Ca2+]i）时空动态的影响。处理4 - 6小时后，GA3诱导糊粉层原生质体中[Ca2+]i从50 nM持续增加到150 nM。[Ca2+]i的增加比GA3诱导的α-淀粉酶合成和分泌增加提前4小时。[Ca2+]i的升高在周边细胞质中最高，可能在协调那里的分泌事件中起作用。将孵育培养基中的Ca2+水平降低到500 microM以下，可抑制[Ca2+]i的增加以及GA3诱导的α-淀粉酶合成和分泌的刺激。这些数据表明，GA3可能通过增加质膜上Ca2+的内流来增加[Ca2+]i。ABA在3小时内逆转了GA3对[Ca2+]i的影响，这比其对α-淀粉酶产生的影响能被检测到提前2小时。因此，[Ca2+]i的变化可能在介导GA3和ABA对糊粉层细胞中α-淀粉酶合成和分泌的影响中起作用。
