An Electron Microscope Study of Spore Structure and Development in Alternaria brassicicola

Abstract

SUMMARY: Each cell of the mature spore of Alternaria brassicicola has a two-layered wall, the layer distant from the protoplast being melanized. The mature septa are five-layered, having two layers of secondary wall on either side of the septal partition which is itself three-layered. Each septum has one simple pore. New spores are produced by an outgrowth, through a pore, of the inner wall layer of the mother cell. Young spores have many small mitochondria and much vesicular endoplasmic reticulum; as they mature, lipid bodies and an unknown polyglucoside are produced. Mature spores have glycogen but very little if any lipid. The suggestion by other workers that vesicular endoplasmic reticulum, multivesicular bodies and lomasomes are involved in wall formation is supported.