摘要：Fluorescence light microscopy and scanning electron microscopy were used to study penetration by the yeast Nematospora caryli through the seed coat and into the embryonic tissues of oriental mustard seed (Brasslca iuncea). Infection of the seed was associated with its physical injury; however, it was evident that the yeast was capable of successfully invading healthy plant cells. The pathological process was followed in parallel using both the above types of microscopy. Foci of yeast infection on the seed coat outer surface were characterized by swelling of the infected epidermal cells. Nematospora hyphae were seen in the lumina of the seed coat palisa de cells and spread laterally when the hyaline layer between the seed coat and embryo was reached. Sites of infection at the surface of cotyledon cells appeared as zones of localized erosion. Asci and spores were visible, embedded in disorganized and disintegrating plant tissue.
