CYTOLOGICAL STUDIES OF HELMINTHOSPORIUM SATIVUM

Abstract

Cytological studies of Helminthosporium sativum P.K. & B. showed that a mechanism exists for the perpetuation of heterokaryons. Septa are laid down in such a way that usually the hyphal tips and mycelial cells are initially multinucleate. Hyphal fusions occur in all parts of the colony and nuclei have been observed in the bridging hyphae. Two or more nuclei generally enter the young conidiophore and several nuclei invariably enter the young conidium before the latter is delimited from the conidiophore. The multicellular, multinucleate conidia exhibit polar or bipolar germination but only the nuclei in the terminal cells of the conidium enter the germ tubes; the remaining cells and their nuclei subsequently degenerate. Germination of complete conidiophores or portions of conidiophores was also observed.