发根农杆菌诱导的决明毛状根与实生根的解剖结构比较

Anatomical comparison of the hairy roots induced by Agrobacterium rhizogenes and the seedling roots of Cassia obtusifolia L.

为找出发根农杆菌诱导的决明毛状根与其无菌实生根的形态和解剖特征差异,采用体视显微观察、石蜡切片,番红-固绿染色及多糖-高碘酸-席夫反应染色,显微观察比较决明毛状根与实生根的形态、解剖结构及淀粉粒分布.结果发现,决明毛状根粗细均匀,根尖较实生根粗壮,有较多根毛;毛状根较小的表皮细胞和皮层细胞排列紧密而不规则;内皮层细胞排列紧密,细胞间隙小,凯氏带不明显;毛状根初生木质部为二原型,而实生根为四原型;毛状根形成层细胞较实生根细胞小、排列紧密、层数多;毛状根根冠几乎没有淀粉粒,而实生根有较多淀粉粒.这些结果表明,决明毛状根与实生根在外部形态和解剖结构上均存在较大差异.

In order to find out the morphological and anatomical differences between the Agrobacterium rhizogenes induced hairy roots and the aseptic seedling roots of Cassia obtusifolia L.,stereomicroscopic and light microscopic observation on the paraffin sections stained with safranine/fast green,and with polysaccharide-periodate-Schiff（PAS）reaction were used in this research to compare the morphology,anatomy and the distribution of starch granules in the hairy roots and the seedling roots.It was found that the hairy roots were more uniform in thickness,their root-tips were thicker and more robust,and had more root hairs than the seedling roots;the smaller epidermal cells and the cortex cells of the hairy roots were more closely and irregularly arranged;the endodermal cells were more closely arranged with smaller intercellular space and no apparent Casparian strips;the protoxylem of the hairy root was diarch,while that of the seedling root was tetrarch;the cambial cells of the hairy roots were smaller,more closely arranged and had more layers of cells;the root caps of the hairy roots almost had no starch granules,whereas those of the seedling roots had quite a lot.This result shows that considerable differences existed in both the morphology and anatomy of the hairy roots and seedling roots of Cassia obtusifolia L..