Genetic and environmental effects on the growth and differentiation of wheat somatic cell cultures

Abstract

Mature and immature embryos of 25 wheat (Triticum aestivum L.) cultivars and five additional Triticum species were cultured in vitro under a wide variety of environmental conditions. Callus proliferation rate varied significantly among genotypes and among phytohormone sources and concentrations. Optimum medium for callus proliferation contained 0.5–1.0 mg I⁻¹2,4,5-T and 0.1 mg I⁻¹ kinetin. Shoot differentiation occurred at low frequency (≤3 percent of colonies responding), but varied significantly with genotype. Two lines derived by regeneration from embryo culture proliferated in culture no faster than their respective parent cultivars, although the within-line variability for callus proliferation was significantly less than the variability within parent cultivars. One of the embryoculture derived lines differentiated shoots more frequently than the parent cultivar. Histological examination of calli undergoing growth and differentiation strongly supported the hypothesis that shoot differentiation derived from meristems formed de novo within the callus.