무 (Raphanus sativus L.) 자엽에서 산화질소 (Nitric oxide)에 의해 유도된 부정근 형성과정에 대한 칼슘의 효과

초록

The treatment of radish cotyledons with a nitric oxide (NO)- releasing substance, sodium nitroprusside (SNP) resulted in an increased adventitious root development in a dose-dependent manner. However, this NO- mediated enhancement effect was reversed when either 0.5 mM EGTA (an extracellular Ca2+chelator) or 0.1 mM LaCl3 (a calcium channel blocker) was applied with 50 µM SNP. Our results also showed that guaiacol peroxidase (GPX) and syringaldazine peroxidase (SPX) activities, which are known to play a key role in rooting, were more largely increased during adventitious root induction in the cotyledons treated with SNP. However, the treatment of cotyledons with SNP plus LaCl3 inhibited the SNP-induced increases in the activities of both GPX and SPX. Trifluoperazine (TFP), an antagonist of calmodulin (a specific calcium-binding protein), also delayed adventitious root formation and significantly reduced the root length and number of the SNP-treated cotyledons as well as the deactivation of GPX and SPX enzymes. In conclusion, our results suggest that calcium is involved in the NO response leading to induction of adventitious root through a regulation of GPX and SPX.