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

Two types of maize somatic embryos, one that develops attached to a callus and the other that grows from a cluster of cells in suspension culture, were studied with pyrolysis-mass spectrometry (Py-MS) and the results were compared with those obtained from zygotic embryos. Comparison of the Py-MS results of the somatic embryos attached to a callus show great resemblance to the zygotic embryos. Neither have mass peaks for phenolic acids and lignin. The Py-MS spectra of the somatic embryos that grow from clusters of cells in suspension culture reveal mass peaks for phenolic acids and lignin. The somatic embryos attached to a callus, however, have an abundance of lipids and starch in the scutellar cells, as do the zygotic embryos, which products obscure the cell wall constituents. Therefore, three successive developmental stages of these embryos were harvested and subjected to chemical and enzymic treatments to solubilize lipids and starch. After these treatments some ferulic acid was observed, but lignin was absent.