核桃子叶不定根发生调控的研究

REGULATION OF JUGLANS REGIA COTYLEDON RHIZOGENESIS

以核桃成熟或近成熟种实子叶为试材 ,在 1 4DKW基本培养基上其顶部 (近胚端 )的生根率达1 0 0 % ,而中部和基部 (远胚端 )的生根率为 0。在生根过程中顶部内源吲哚乙酸 (IAA)表现为初期上升 ,其后稳定在一定水平 ,当根原基开始生长时 (培养 4d)出现一个高峰 ;而中、基部内源IAA水平在培养初期下降 ,而后维持在一定的水平 ;蛋白凝胶电泳分析表明 :62 .8和 3 8.4kDa是与子叶不定根发生相关的蛋白条带 ,在不定根发生过程中 ,该带在子叶顶部表达增强 ,而中部、基部则消失。当培养基中附加一定水平的吲哚丁酸(IBA) ( 0 .5～ 1 0mg·L- 1 )时 ,子叶中、基部被诱导产生不定根 ;附加 2mg·L- 1 IBA ,其内源IAA的变化与子叶顶部在 1 4DKW基本培养基上发根时有相似的趋势 ;同时该处理启动表达了 62 8kDa蛋白条带和抑制表达3 8 4kDa蛋白条带。反之当培养基中附加 6-苄氨基腺嘌呤 (BAP)又抑制子叶生根 ,也抑制了与生根相关的IAA变化和蛋白表达。这一结果和良好的研究模式为从分子水平上深入认识木本植物不定根发生机制奠定了基础。

In vitro rhizogenesis of Juglans regia cotyledons from mature or near mature fruit was investigated. The top, middle and basal sections of the cotyledon showed different rooting capacity. On 1/4 DKW basal medium supplemented no plant growth regulators, the rooting ratio of the top section was 100%, while the middle and basal had no rhizogeneesis. The endogenous indoleacetic acid (IAA) level in the rooting top sections presented as increasing at the culture beginning, then maintaining at a level during the differentiation of root primordia, and increasing again to form a peak when the primordia started to grow (4 days after culture). However, the IAA in the middle and basal sections without rhizogenesis showed decreasing dramatically at the culture beginning, then maintaining at a certain level. SDS_PAGE demonstrated that 62.8 and 38.4 kDa were the rooting related protein bands in walnut cotyledon. Former up_expressed and later down_expressed in the rhizogenesis. Application of exogenous indolebutyric acid (IBA)(0.5～10 mg · L -1)in the medium had effects to induce the middle and basal sections to root and to regulate their endogenous IAA changes similar to that happened in the rooting of the top section. Meanwhile it up-regulated the expression of the 62.8 kDa proteins and down-regulated 38.4 kDa protein bands. Exogenous 6-benzylaminopurine (BAP) inhibited the rooting of cotyledon top section and restrained the rooting-related changes on IAA and proteins. The system that IBA induced J.regia cotyledon rooting by regulating rooting-related IAA and proteins could be taken as a good research model for the further investigations on molecular rhizogenesis mechanism of woody plants.