一氧化氮参与乙烯诱导黄瓜不定根的形成

以黄瓜(Cucumis sativus L.)切去初生根的幼苗外植体为试材,研究了乙烯和一氧化氮(NO)对其不定根形成的影响及其相互关系。结果表明,外源乙烯供体乙烯利(Ethrel)可显著促进黄瓜外植体不定根的形成,呈现明显的剂量效应,最适浓度为0.5μmol·L~(-1)。Ethrel和NO共同处理的外植体不定根的数量和根长显著高于Ethrel和NO单独处理,但Ethrel的促进作用可被NO的清除剂c-PTIO、一氧化氮合酶(NOS)抑制剂L-NAME和硝酸还原酶(NR)抑制剂NaN_3所逆转,说明乙烯和NO在黄瓜外植体不定根形成过程中具有协同诱导作用。外源乙烯引起黄瓜外植体内源NO含量的增加,亦提高了植株体内合成NO的NOS和NR酶的活性以及NOS和NR基因的相对表达量。可见,NO在乙烯诱导黄瓜不定根形成的信号途径中起重要作用。

Nitric Oxide is Involved in Ethylene-induced Adventitious Root Development in Cucumber Explants

Cucumber（Cucumis sativus L.）was used to understand the effects of ethylene（ETH）and nitric oxide（NO）on rooting of plant explants. The results showed that the effects of ETH on adventitious rooting in cucumber explants were dose-dependent，and 0.5 μmol · L^-1 ethrel treatment was the most effective concentration to promote the adventitious rooting. The root number and root length of explants treated with ETH and NO was significantly higher than that of explants treated with ETH or NO alone. But the positive effect of ETH could be reversed by NO scavenger 2-（4-carboxy-2-phenyl）-4,4,5,5- tetramethylimidazoline-1-oxyl-3-oxide（c-PTIO），nitric oxide synthase（NOS）inhibitor N-nitro- L-arginine methyl ester（L-NAME）or nitrate reductase（NR）inhibitor NaN₃，indicating that there might exist synergistic action between ETH and NO on mediating cucumber adventitious rooting. ETH treatments enhanced endogenous NO levels in explants. Meanwhile，the exposure of cucumber explants to ETH up-regulated NOS and NR activity and their gene relative expression. Together，these results indicate that NO may play crucial roles in the adventitious root development induced by ETH.