Lipid bodies in tissue culture, somatic and zygotic embryo of Daucus carota L.: a qualitative and quantitative study

Abstract

Qualitative and quantitative electron microscopic examinations were made to study lipid body accumulation in zygotic embryos and in cells and tissues of Daucus carota L. cultured in vitro. Lipid bodies were present in all types of tissue analysed. The somatic embryos, callus and cells in suspension culture had lipid bodies rather similar in appearance and no protein bodies were detected. A few lipid bodies which were indistinct and diffuse in structure without any bordering membrane, perhaps were the so-called nascent lipid bodies. Quantitative analysis using an image analysis system showed that the torpedo-shaped somatic embryos had a significantly higher proportion of lipid body area/section area than callus cells, cells in suspension culture, and other early stages of somatic embryos. Somatic embryos grown in media with different supplements had higher numbers of lipid bodies as well as a higher proportion of lipid body area/section area compared to torpedo-shaped embryos grown in basal medium containing 2% sucrose. Zygotic embryos 17 days after pollination had an ultrastructure similar to that of somatic embryos. Late stage embryos 45 days after pollination were very rich in lipid bodies and ultrastructurally similar to other common oil-bearing seeds.