A STUDY OF THE LIFE CYCLE OF NEOCOSMOSPORA AFRICANA (VON ARX)
A STUDY OF THE LIFE CYCLE OF NEOCOSMOSPORA AFRICANA (VON ARX)
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Date
2014-07-11
Authors
ONUORAH, OKAY MARTINS OREFO
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Abstract
The life cycle of Neocosmospora africana was studied from single
spores. These unisporous cultures developed to yield mature perithecia.
The fungus was found to be homothallic.
Media containing different carbon sources were tested for the
ability of the fungus to maintain growth on them. All carbon sources
tested supported the growth and sporulation of the fungus. Of the
different nitrogen sources tested, vegetative growth was obtained on
all while sporulation occurred on all media except the one containing
ammonium sulphate as a result of changes in hydrogen-ion concentration
despite the heavy buffering of the medium.
Reproductive morphogenesis of the fungus was studied from
surface static cultures on liquid glucose asparagine medium.
Production of conidia occurred following the establishment of the
mycelium. Development of perithecia in the same culture occurred
much later following decline in growth rate and nutrient depletion.
The ascogonium was found to be a coiled hyphal branch. The
uninucleate and binucleate cells of the ascogonium become surrounded
by hyphal cells that develop from adjacent stalk cells. Growth of
the perithecium is caused by the divisions and enlargement of cells
of hyphae surrounding the ascogonium. Meristematic cells in the
apical region of the young perithecium give rise to an ostiole lined
by periphyses.
The centrum comprises the ascogonium and its descendant
structures. The asci and evanescent paraphyses are borne on a
slightly convex hymenium restricted to the basal central part of
the centrum. The perithecial cavity increases from the deliquescence
of the inner pseudoparenchymatous walls.
The asci develop from the ascogenous system without crozier
formation. Asci are double walled, cylindrical structures and are
characteristically 8 - spored. Two successive mitoses in each
ascospore followed by cell divii3ion synchronise with the maturation
of the spores.
Description
A Thesis presented for the degree of Master of Science
in Botany in the Department of Biological Sciences
of Ahmadu Bello University, Zaria.
by
OKAY MARTINS OREFO ONUORAH^ B.Sc. (Hons.)
Keywords
LIFE CYCLE,, NEOCOSMOSPORA,, AFRICANA,, (VON ARX),