Calli Ultrastructure of Globularia trichosantha ssp. trichosantha

Abstract

Background and Purpose: This study aimed to produce calli with explants of aseptic seedlings after germination of G. trichosantha ssp. trichosantha seeds by plant tissue culture method and to examine the ultrastructure of the produced calli with electron microscope preparation.

Materials and Methods: Seeds of G. trichosantha ssp. trichosantha were germinated in hormone-free Murashige and Skoog in in vitro conditions. Hypocotyl, epicotyl, cotyledon, young primer leaf, apical meristem and root explants taken from 30-day aseptic seedlings were transferred to Murashige and Skoog media for callus production which contained varying concentrations of 6-benzilamynopurine, indole acetic acid and 2,4 dichlorophenoxyacetic acid.

Results: Two types of calli were determined: Yellow calli (Type 1) and Black calli (Type 2) with darkened colour and appearance that have not lost their development properties. Following lead staining, thin sections were examined by transmission electron microscope. The best callus production occurred at the Murashige and Skoog medium containing indole acetic acid and 6-benzilamynopurine and in root explants. The cells of Type 1 calli were spherical and large. The cells contained usually one nucleus and nucleolus. Also the cells contained a very large vacuole, endoplasmic reticulum, golgi complex, mitochondria, ribosomes, plastids. Deformed cells and spherical cells were determined in Type 2 calli. The cells were observed to have smaller vacoules and higher numbers of mitochondria different from Type 1 calli. Type 1 and Type 2 calli showed bulging mitochondrial cristae. Electron-dense droplets were observed in vacuoles of both Type 1 and Type 2 calli.