KT和Ca2+对绿豆下胚轴原生质体的体积和CaM含量的影响

Effects of KT and Ca2+ on the Change in Volume of Protoplasts and CaM Content in Hypocotyl of Etiolated Mung Bean Seedlings

摘要:

以黄化绿豆幼苗下胚轴原生质体为材料,探讨钙信使系统在KT诱导原生质体体积变化中的作用。1 μmol/LKT可诱导含钙培养液中绿豆下胚轴原生质体膨大,处理后30 min达到最大体积。Ca²⁺通道阻断剂Verapamil、Ca²⁺通道竞争性抑制剂LaCl₃和钙调素拮抗剂TFP、CPZ可明显抑制KT诱导的原生质体膨大。另一方面,无论是KT处理还是对照(CaCl₂单独处理),原生质体内CaM含量均在处理后30 min时达到峰值,前者是后者的5倍。在KT+CaCl₂处理液中加入5 μmol/L Verapamil、50 μmol/L LaCl₃、5 μmol/L TFP或CPZ后原生质体内CaM含量都大大降低。以上结果表明,CaM可能与Ca²⁺共同参与KT的信号传递。

Abstract:

The role of calcium ion in kinetin (KT) signal transduction was studied with etiolated mung bean (Phaseolus radiatus L) hypocotyl protoplasts. The volume of protoplasts maintained at a constant osmotic potential at 20±2℃ began to swell 10 minutes later when treated with 1 μmol/L KT in the present of CaCl₂, and reached their maximum at 30 minutes, then declined to the same level as the control one (CaCl₂ only) at 60 minutes. The swelling of protoplasts induced by KT could be significantly inhibited by Verapamil (Ca²⁺ channel blocker) or LaCl₃ (Ca²⁺ channel competitive inhibitor) respectively. Calmodulin antagonists TFP, CPZ and W₇ could obviously inhibit protoplasts swelling induced by KT. CaM levels in protoplasts reached their peaks at 30 minutes whether treated with or without KT, the CaM content of the treated one being about five times more than that in treatment without KT. However, when KT and CaCl₂ solutions were added with 5μmol/L CPZ, TFP or 0.5μmol/L W7, CaM level in protoplasts declined greatly. It is suggested that calcium acts as the second messenger in KT-induced swelling of protoplasts in this system and Ca²⁺-CaM may play an important role. The present study did not exclude the possibility of involvement of other cellular signaling system.