무 (Raphanus sativus L.) 자엽에서 부정근 형성에 대한 nitric oxide와 H₂O₂의 역할

We examined the physiological action mechanisms of nitric oxide (NO) on adventitious root formation in cotyledons of radish seedlings with their primary roots removed. The results showed that the effects of exogenous sodium nitroprusside (SNP: a NO donor) and H₂O₂ on promoting the formation and growth of adventitious roots were dose dependent, with maximal responses at 50 μM SNP and 1 mM H₂O₂. Especially, treatment of cotyledons with 50 μM SNP rapidly enhanced the endogenous levels of NO and H₂O₂. In addtion, cotyledons treated with 0.5 - 2 μM aminotriazole (AT), a catalase inhibitor, showed more remarkable adventitious root growth and development than that of the control. However, the effect of 50 μM SNP on promoting the formation and growth of adventitious roots was eliminated by 0.1 mM ascorbic acid (AsA). Additionally, the activity of catalase was significantly reduced by 50 μM SNP. Based on the above results, it was thought that the inhibition of catalase by NO can induced H₂O₂ accumulation, thereby leading to trigger a signaling response inducing adventitious root formation and growth in radish cotyledons.