云杉矮槲寄生内寄生系统的解剖学研究

Anatomical Study on Endophytic System of Dwarf Mistletoe(Arceuthobium sichuanense)

采用石蜡切片和显微观察的方法,以被云杉矮槲寄生侵染的青海云杉枝条为材料,从解剖学水平观察云杉矮槲寄生的内寄生系统。结果表明:云杉矮槲寄生的内寄生系统由分布在寄主皮层内的皮层根和镶嵌在寄主木质部中的吸根组成。皮层根可以沿着寄主枝条,通过挤压寄主皮层细胞的方式扩展,并穿透寄主表皮层形成云杉矮槲寄生的寄生芽;在靠近或接触寄主次生韧皮部时形成吸根,吸根顶端细胞定向穿透寄主韧皮部和形成层,侵染木质部,并沿木射线方向生长。当云杉矮槲寄生侵入寄主以及皮层根向外生长时,寄主表皮层发生加厚现象。随着云杉矮槲寄生侵染部位的寄主皮层细胞数增多,引起枝条膨大。研究认为,云杉矮槲寄生可以进行系统侵染,反映了云杉矮槲寄生与其寄主在组织水平上的相互作用。

The anatomy of entophyte system of Arceuthobium sichuanense was observed with paraffin sectioning and light microscope.The endophytic system consisted of cortical strands within the bark and sinkers embedded in the xylem.The cortical strands extended by squeezing the cortex cells of host.When penetrating the periderm of host,the cortical strands developed aerial shoots;when contacting with and near to the secondary phloem of host,the cortical strands developed sinkers.Then,the sinkers penetrated the phloem and cambium of host,extended to the xylem and grew along with the xylem rays of host.The periderm of host became thickened when the penetration pegs and the cortical strands penetrated it.The number of host cortex cells increased where localized infection of A.sichuanense occurred.The results indicated that A.sichuanense can develop systemic infection and reflected the interaction between A.sichuanense and host at histopathological level.