木薯试管微型薯与田间块根的结构发育比较

以华南8号木薯(Manihot esculenta Crantz cv.South China 8)无菌苗嫩茎为材料,采用植物组织培养方法获得试管微型薯,利用组织解剖学及组织化学方法研究木薯试管微块根(微型薯)的形态结构发育以及田间木薯块根形态结构发育,结果表明:木薯在组培条件下形成的微型薯没有次生结构的分化,微型薯的膨大在结构上表现为初生根皮层细胞体积的增大以及细胞间隙的增加。而田间块根的膨大在结构上表现为次生结构的产生以及大量淀粉的积累;组培微型薯和田间块根淀粉积累相比,存在时间上和空间上的差异,早期生长的微型薯没有淀粉的积累,生长5~10 d后在皮层薄壁细胞可见淀粉粒分布。而田间生长的木薯块根的淀粉是在初生根产生次生结构后就开始积累,淀粉主要积累在次生木质部,少部分分布于皮层薄壁细胞和韧皮部。

Structure Development of Cassva Tuberous Root in Field-grown and in vitro

Manihot esculenta Crantz cv. South China 8 was used as the experimental material. The method of tissue culture was applied to obtain the micro-tuber. The development and morphological structure of cassava in micro-tuber and tuber was studied by the method of anatomical technology. The conclusions of the analysis are as follows: 1) In vitro, there was no secondary tissue formed in the whole procession of micro-tuber induction. The expansion of micro-tuber was the results of the enlargement of cortical parenchyma cell volume and intercellular space. Not like micro-tuber, the tuber in field-grown formed secondary tissue and a large number of starch grains stored in xylem parenchyma cells. 2) There was a time and space difference in starch accumulation between micro-tuber root and tuber. There was no starch grains in micro-tuber until five to ten days cultured. A small amount of starch grains occurred in the cortical parenchyma cells. The starch in field-grown cassava roots was produced in the primary root after secondary structure beginning to accumulate. Starch mainly accumulated in the secondary xylem parenchyma cells. A small number of distribution in the cortex and phloem.