胡杨不定根原基发生的分生细胞结构特征及内源激素变化分析

Meristem Cell Structure and Endogenous Hormones Changes during the Adventitious Root Primordia Formation of Populus euphratica Oliver

以胡杨实生苗去根插穗为试材,采用显微技术、气质(GC/MS)联用技术和同工酶分析技术观察和研究了外源3-吲哚丁酸(IBA)对其不定根原基(干细胞)形成的影响。结果表明:(1)胡杨插穗培养在无IBA的培养基上,36h时有大核细胞发生,60 h时大核细胞聚集成团形成根原基,72 h时生成不定根;而添加了IBA的培养基上插穗培养60 h时大核细胞分散,出现许多薄壁细胞,72 h时薄壁细胞变大,没有根原基的形成和根的发生,表现出细胞组织愈伤化,不再分化出干细胞。添加外源IBA抑制了胡杨插穗不定根形成。(2)组织化学观察显示,在无IBA的培养基上的插穗,60 h时具双环状核仁的干细胞细胞质浓,富含蛋白质;而此时添加了IBA的插穗,具双环状核仁的细胞细胞质很少,蛋白质含量也少。(3)整个胡杨不定根形成的过程中,内源激素IAA和ABA可能作为诱导根原基发生的重要信号分子;内源激素IAA和GA3处于一个较稳定状态,有利于不定根的形成。(4)过氧化物酶(POD)2b酶带的持续表达有利于根原基的诱导;淀粉酶在60 h时表达增强,是根原基发育的标志;根原基诱导时不需要酯酶,而根原基发育时需要酯酶。

The formation process of adventitious root primordium in seedling cuttings was investigated using microscopy,GC/MS and isozyme analysis techniques about exogenous IBA impact in Populus euphratica Oliver. The results showed that： （1）On no IBA medium incubating for 36 h, the large nuclear cells were formed in cuttings;At 60 h,the large nuclear cells gather into mass and root primordium formation;At 29, h,adventitious roots generated. However,on medium plus IBA,large nuclear cells scattered, and a number of parenchyma cells presented ; At 72 h,parenchyma cells became target,and there were no root primordium formation,no adventitious root generated, and instead callus produced and no longer differentiated stem cells. That means the added exogenous IBA inhibit adventitious root formation of Populus euphratica cuttings. （2）Histochemical observations showed that in the absence of IBA on the medium for 60 h,the stem cells with double ring of nucleolar had dense cytoplasm,rich in protein;But on the medium with 1BA, the cell with double ring of nucleolar had little less cytoplasm and protein content. （3）During the whole process of adventitious root formation,endogenous hormones IAA and ABA probably happen as an important signaling moleeule for induced root primordium. While endogenous hormones IAA and GAa in a more stable status,is conducive to the formation of adventitious roots. （4）The band of peroxidase （POD） 2b expression was in favor of continuing the root primordium induction. The amylase increased expression in 60 h,was as a sign of root primordium development;Esterase expression was weaker in stage of root primordium induction,but stronger during root primordia development.