Structure and macromolecular composition of the seed coat of the Musaceae

Mature seed coats of representatives of all three genera of Musaceae were analysed for macromolecular composition with various mass spectrometric techniques and compared with scanning electron microscopy and light microscopy in combination with histochemical techniques. Mass spectrometric techniques are more sensitive and more specific in identifying macromolecular compounds than histochemical methods. The macromolecular 'fingerprint' of the seed coats of Musaceae showed unique components of aromatic phenols. The seed coat structure of all three genera is homogeneous within the Musaceae. It is characteristic at the family level and most complex within the Zingiberales. Very remarkable are the separation of the outer cell walls from the exotestal layer, exposing a secondary surface with silica crystals, and the relatively thick mesotesta which protects the seed, e.g. against the biting forces and passage through the digestive tracts of dispersing agents. Germination takes place with an operculum and is facilitated by a predetermined rupture layer in the micropylar collar. The musaceaous seed presents a good example of the solution of conflicting demands of protection and germination. (C) 1996 Annals of Botany Company