绒毛白蜡嫩枝扦插生根的解剖学特征与内源激素变化

Anatomy and endogenous hormone changes of softwood cutting rooting of Fraxinus velutina

【目的】研究绒毛白蜡嫩枝扦插生根过程中的形态解剖特征,分析内源激素含量变化,探讨其扦插生根机制,旨在为培育绒毛白蜡良种壮苗提供理论参考。【方法】以绒毛白蜡当年生嫩枝为材料,以200 mg·L^(-1) IBA浸泡20 min为处理组,以清水浸泡为对照组,通过石蜡切片技术观察根原基发源部位及生根过程,利用ELISA法测定插穗基部IAA、ABA、ZR及GA_3含量。【结果】处理组扦插生根率为96.7%,对照组生根率为80.7%,两者之间差异显著。绒毛白蜡茎段内未观察到潜伏根原基,属诱导生根类型,根原基来源于与形成层相邻的韧皮薄壁细胞,为皮部生根类型。其扦插生根的过程可以分为根原始细胞的形成和分化、根原基的形成及不定根的表达3个阶段。扦插生根过程中处理组和对照组的IAA含量始终处于上升趋势,且处理组的IAA含量始终高于对照组的IAA含量;处理组的GA_3含量先下降后升高,而对照组的GA_3含量变化趋势则恰好相反,且对照组的GA_3含量始终高于处理组的GA_3含量;处理组的ZR含量先上升后下降,对照组的ZR含量则一直处于上升状态;处理组的ABA含量变化趋势较复杂,呈现出上升—下降—上升的趋势,对照组的ABA含量则是先下降然后持续上升,且处理组的ABA含量始终高于对照组的ABA含量。【结论】绒毛白蜡为皮部诱导生根类型,根原基发源于形成层附近的韧皮薄壁细胞,在生根过程中处理组和对照组的IAA含量持续升高,与不定根的形成、发育关系密切,但两者体内的GA_3、ZR及ABA含量变化趋势不一致,说明外源IBA的使用对绒毛白蜡体内的激素有一定的调节作用,并使其朝着有利于生根的方向发展。

【Objective】To study the morphological and anatomical characteristics during the rooting process of Fraxinus velutina softwood cuttings,analyze the changes in endogenous hormone content,and explore the rooting mechanism of its cutting,aiming to provide theoretical reference for cultivating excellent and strong seedlings of F.velutina.【Method】Using the current year shoots of-1 F.velutina as materials,the treatment group was soaked in 200 mg·L IBA for 20 min,and the control group was soaked in water.The origin and rooting process of root primordium were observed by paraffin sectioning technology,and the contents of IAA,ABA,ZR and GA3 in the base of cuttings were determined by ELISA.【Result】The rooting rate of the treatment group was 96.7%and that of the control group was 80.7%,and there was a significant difference between the two groups.There was no latent root primordium was observed in villosus,which belonged to the induced rooting type.The root primordium came from phloem parenchyma cells adjacent to the cambium,which was the type of skin rooting.The rooting process could be divided into three stages:the formation and differentiation of root primordial cells,the formation of root primordia and the expression of adventitious roots.The IAA content of the treatment group and the control group was always in an upward trend during the cutting rooting process,and the IAA content of the treatment group was always higher than that of the control group.The content of GA3 in the treatment group decreased first and then increased,while the change trend of GA3 content in the control group was just the opposite,and the content of GA3 in the control group was always higher than that in the treatment group.The ZR content of the treatment group increased first and then decreased,while the ZR content of the control group was always on the rise.The change trend of ABA content in the treatment group was more complex,showing an upward-downward-upward trend,and the ABA content in the control group was first decreased and then continuously increased,and the ABA content in the treatment group was always higher than that in the control group.【Conclusion】F.villosus is a type of skin induced rooting,the root primordium originates from the phloem parenchyma cells near the cambium.During the rooting process,the IAA content of the treatment group and the control group continues to increase,which is closely related to the formation and development of adventitious roots.However,the change trends of GA3,ZR and ABA contents in the two groups are not consistent,indicating that the use of exogenous IBA has a certain regulatory effect on the hormones in the body of villosa,and make it develop in the direction of rooting.