CYTOHISTOLOGICAL STUDIES ON THE MORPHOGENESIS OF RACHES AND LEAVES OF BRASSICA NAPUS L. IN TISSUE CULTURES

The calli were induced from the raehesand leaves of Brassiva napus L. on MS medium supplemented with 2,4-D, ADE, 6-BA. The plantlets were obtained after transferred the calli to MS medium with addition of 0.1-2mg/L NAA and 0.5-5mg/L 6-BA.The developmental stages of calli were observed i.e.cell activation, cell division and cell differentiation. The callus may be originated from epidermis, cortex parenchyma, pith parenchyma, phloem and xylem parenchyma of raches and mesophyll, branch veins parenchyma of leaf.Upon transferring the calli to the solid medium, two kinds of meristerustic tissues were formed——meristematic cellular mass and vascular nodule. The vascular nodule became a growth center without differentiation in early stage, but they were differentiated tracheids later in the inner surrounded by the cambium-like cells.The buds primordia are universally produced exogenously from meristematie cellular masses and the roots primordia are originated endogenously at random from either meristematic cellular mass or vascular nodule. Sometimes the roots formation from peripheral layer of callus were also observed.The relation between cell differentiation and tissue differentiation was discussed.