A Scanning Election Microscope Study of Surface Differentiation in Triticale Callus ¹

Investigations of proliferative and senescent callus of soybean

“…cells. In contrast to the elongated and small spherical ceils reported in senescent triticale callus (Sharma and Bello 1982), layers of a fluffy or furry-looking mucilaginous exudate covered the cell surfaces of senescent Glycine callus (Fig, 4), Some areas were covered with smooth, flat platelets of material; gaps and cracks in the surface material allowed limited examination of the cells beneath. The material was present after both freeze-drying and washing the callus tissue, and was not due to critical point drying.…”

“…Callus cultures are generally classified as either developmental or proliferative; i,e, the callus is developing through organo-or embryogenesis, or it is growing and expanding in cell size and number, A third classification is senescent callus, in which the callus is slow-growing at best, with no signs of development, There are relatively few histological studies or SEM observations of callus in the literature. Elongated cells and small, spherical embryogenic cells were found in coffee {Coffea arabica) callus cultures, in which segmentation of the callus mass occurred and cells sloughed away from the embryogenic tissue (Sondahl et al, 1979), In a study of surface differentiation in triticale (Triticosecale) callus, root and shoot development were clearly visible in the micrographs (Sharma and Bello 1982), Root growth was initiated earlier and advanced more rapidly than shoot growth. Mucilaginous exudates have been observed on the surfaces of soybean and tomato callus tissues, with sugars Identified as the primary components (Kokate and Radwan 1979), Soybean (Glycine max L, Merr,) is recalcitrant to regeneration from in vitro cultures, except via embryo-genesis from immature cotyledons (Lazzeri et al, 1985), Proliferative and sensescent soybean calii were examined to visualize differences in these types of calli.…”