一氧化氮和乙烯在黄瓜不定根发生过程中的作用及其关系

Roles and Relationships of Nitric Oxide and Ethylene on Adventitious Root Development of Cucumber

为探讨乙烯(ethylene)和一氧化氮(NO)在植物不定根形成过程中的作用及其相互关系,以黄瓜为试材,运用生理学、药理学和细胞生物学的方法研究NO参与乙烯诱导不定根生成过程中细胞周期时相、光合参数和营养物质含量的变化。结果表明,50μM NO供体S-亚硝基-乙酰青霉胺(SNAP)可显著促进黄瓜外植体不定根的形成。乙烯利(ethrel)和SNAP可以单独或协同促进黄瓜不定根的发生,且共处理效果更显著;处理ethrel的根数和根长分别较对照高62%和103%,处理ethrel+SNAP的根数和根长分别较对照提高了82%和128%。NO清除剂c PTIO能抑制乙烯对不定根形成的促进作用,但对内源乙烯的释放无影响,说明在不定根生成过程中NO处于乙烯信号通路的下游。乙烯和NO提高了黄瓜外植体内可溶性总糖、可溶性蛋白、叶绿素含量和叶绿素荧光参数,降低了外植体淀粉含量;在12 h时,处理ethrel的外植体可溶性糖含量、叶绿素a含量和最大光化学效率(Fv/Fm)值较对照分别增加了75%、190%和28%;处理ethrel的淀粉含量在4 h时较对照降低了33%。ethrel和SNAP促进细胞从G1期向S期转移,激活细胞周期活性;同时,c PTIO逆转了乙烯对营养物质含量、光合系统及细胞周期的诱导效应。可见,乙烯诱导黄瓜不定根的发生过程需要NO的参与。本研究结果为进一步探讨乙烯和NO信号调控在植物生长发育补充了新的资料,拓展了对植物不定根发生调控机制的认识。

Cucumbers （Cucumis sativus L. ） were used to investigate the role and relationship between ethylene and NO in the development of adventitious roots. As well, with the methods of physiology, pharmacology and cell biology to study the changes of cell cycle phase, photosynthetic system and nutrient content during ethylene-induced adventitious rooting involving the nitric oxide pathway. Treatments with different dosages of SNAP significantly affected the formation of adventitious root. The greatest rooting ability was observed in 50 μM SNAP-treated explants. Ethrel-releasing compound ethylene and SNAP treatments promoted the adventitious rooting of cucumber either alone or in their combination. The root number and root length of ethrel treatment were 62% and 103% higher than that of the control, respectively. The root number and root length of ethrel ＋ SNAP increased by 82% and 128% over the control respectively. The application of both ethylene and NO significantly increased root number and length of the explants. It was observed that the effect of ethylene could be blocked by the specific NO scavenger 2 - （4 -carboxyphenyl） -4,5, 5 tetramethyimidazo-inel -oxyl -3 -oxide potassium salt （cPTIO）. However, there were no effect on endogenous ethylene production, indicated that NO may be acting downstream in ethylene signaling pathway during adventitious root formation. Ethylene and NO treatments at appropriate dosage increased the content of water soluble carbohydrate and water soluble protein and the content of chlorophyll and chlorophyll fluorescence parameters but decreased the content of starch of explants during rooting. At 12 h, the content of water soluble carbohydrate, Chlorophyll a and FJFn of ethrel treatment were 75% , 190% and 28% more than the control, respectively. The content of starch in the control treatment was 33% lower than that in ethrel treatment at 4 h. Ethylene and NO treatments activated cell cycle with the transition of cell from GI to S phase. While, ethylene-induced the changes of nutrient, photosynthesis and cell cycle were reversed by cPTIO. Thus, NO was required in ethylene-induced adventitious root formation process. This study provides some academic reference to the study of plant growth and development regulated by ethylene and nitric oxide, expands and enriches the knowledge of the mechanism of adventitious root formation in plant.