CELL-WALL DEVELOPMENT IN MAIZE SOMATIC EMBRYOS STUDIED BY PYROLYSIS MASS-SPECTROMETRY

Two types of maize somatic embryos, one that develops attached to a ca llus and the other that grows from a cluster of cells in suspension cu lture, were studied with pyrolysis-mass spectrometry (Py-MS) and the r esults were compared with those obtained from zygotic embryos. Compari son of the Py-MS results of the somatic embryos attached to a callus s how great resemblance to the zygotic embryos. Neither have mass peaks for phenolic acids and lignin. The Py-MS spectra of the somatic embryo s that grow from clusters of cells in suspension culture reveal mass p eaks for phenolic acids and lignin. The somatic embryos attached to a callus, however, have an abundance of lipids and starch in the scutell ar cells, as do the zygotic embryos, which products obscure the cell w all constituents. Therefore, three successive developmental stages of these embryos were harvested and subjected to chemical and enzymic tre atments to solubilize lipids and starch. After these treatments some f erulic acid was observed, but lignin was absent.