Structural changes of cell surface in callus of Fagopyrum esculentum Moench. during induction of morphogenesis

Scanning electron microscopy was used to study the structure of callus of Fagopyrum esculentum Moench. during induction of morphogenesis. It was found that transferring of callus on the medium lacking growth regulators induced several simultaneous developmental programs: embryoidogenesis, rhizogenesis, and gemmogenesis. The program of embryoidogenesis prevailed over the others. Various morphological structures were found to appear on the callus surface in the following order: trichome (on the 2nd day), roots (the 2nd or 3rd day), embryoids (the 6th to 8th day), and buds (the 10th to 14th day). It was shown that morphogenesis is preceded by loosening of the callus surface and by appearance of the secret on it. Possible functions of secretion in the induction of the observed processes are discussed.