Perera I Y, Heilmann I, Chang S C, Boss W F, Kaufman P B
North Carolina State University, Raleigh, NC, USA.
Plant Physiol. 2001 Mar;125(3):1499-507. doi: 10.1104/pp.125.3.1499.
Plants sense positional changes relative to the gravity vector. To date, the signaling processes by which the perception of a gravistimulus is linked to the initiation of differential growth are poorly defined. We have investigated the role of inositol 1,4,5-trisphosphate (InsP(3)) in the gravitropic response of oat (Avena sativa) shoot pulvini. Within 15 s of gravistimulation, InsP(3) levels increased 3-fold over vertical controls in upper and lower pulvinus halves and fluctuated in both pulvinus halves over the first minutes. Between 10 and 30 min of gravistimulation, InsP(3) levels in the lower pulvinus half increased 3-fold over the upper. Changes in InsP(3) were confined to the pulvinus and were not detected in internodal tissue, highlighting the importance of the pulvinus for both graviperception and response. Inhibition of phospholipase C blocked the long-term increase in InsP(3), and reduced gravitropic bending by 65%. Short-term changes in InsP(3) were unimpaired by the inhibitor. Gravitropic bending of oat plants is inhibited at 4 degrees C; however, the plants retain the information of a positional change and respond at room temperature. Both short- and long-term changes in InsP(3) were present at 4 degrees C. We propose a role for InsP(3) in the establishment of tissue polarity during the gravitropic response of oat pulvini. InsP(3) may be involved in the retention of cold-perceived gravistimulation by providing positional information in the pulvini prior to the redistribution of auxin.
植物能够感知相对于重力矢量的位置变化。迄今为止，重力刺激的感知与差异生长启动之间的信号传导过程仍不清楚。我们研究了肌醇1,4,5-三磷酸（InsP(3)）在燕麦（ Avena sativa）茎节间膨大部分向重力性反应中的作用。在重力刺激后的15秒内，上半部分和下半部分茎节间膨大部分的InsP(3)水平比垂直对照增加了3倍，并且在最初几分钟内，两个茎节间膨大部分的InsP(3)水平都有波动。在重力刺激10至30分钟之间，下半部分茎节间膨大部分的InsP(3)水平比上半部分增加了3倍。InsP(3)的变化局限于茎节间膨大部分，在节间组织中未检测到，这突出了茎节间膨大部分对重力感知和反应的重要性。磷脂酶C的抑制作用阻断了InsP(3)的长期增加，并使向重力性弯曲减少了65%。抑制剂对InsP(3)的短期变化没有影响。燕麦植株的向重力性弯曲在4℃时受到抑制；然而，植株保留了位置变化的信息，并在室温下做出反应。在4℃时，InsP(3)的短期和长期变化都存在。我们提出InsP(3)在燕麦茎节间膨大部分向重力性反应过程中组织极性的建立中起作用。InsP(3)可能通过在生长素重新分布之前在茎节间膨大部分提供位置信息，参与冷感知重力刺激的保留。
