Growth Studies of Three Chlorophyllous Callus Phenotypes of Glycine max

Abstract

The establishment of three chlorophyllous callus phenotypes, Glycine max (L.) Merrill, cultured on a modified Miller's medium is described. Experiments were designed to determine the hormonal requirement necessary to maintain an adequate callus growth rate that would allow for the phenotypical accumulation of chlorophyll in all phenotypes. Addition of α-naphthaleneacetic acid and kinetin, both at 1 mg/liter, to the basal medium fulfilled this requirement. However, callus growth for these phenotypes required only an exogenous supply of cytokinin. All callus phenotypes, when maintained on 3% sucrose, were shown to possess similar growth curves; however, optimal growth rates of these cultured phenotypes occurred on different levels of exogenous sucrose (NG, 2%; LG, 1%; Y, 2%). Sucrose (filtered and autoclaved) and, in most cases, fructose (filtered), when employed as a carbon source in the basal medium, maintained adequate growth rates. Glucose (filtered) supported only minimal callus growth. These callus phenotypes, after two years in culture, showed a certain degree of cell type differentiation as indicated by the formation of isolated tracheoids and in some cases organized tracheoid development. The chromosome complement (2n = 40) was observed to be polyploid.