Degree Name

Master of Science (MS)

Semester of Degree Completion

1982

Thesis Director

Wesley C. Whiteside

Abstract

A cytomorphological study was performed on Podospora curvicolla, a saprophytic Pyrenomycete. Major emphasis was placed on three important features: (I) ascocarp formation and development, (II) centrum structure and (III) ascus development and structure. A comparison with other studies of Podospora and with a genus generally considered closely related, Sordaria, was made to this present study of P. curvicolla.

Initial perithecial formation in P. curvicolla is indicated by a spherical mass of hyphae which may include filaments from many vegetative hyphae, but no apparent ascogonia or antheridia were observed. As the young perithecium matures in P. curvicolla, differentiation of the perithecial wall cells, the pseudoparenchymatous tissue and binucleate ascogenous cells takes place.

Developmental studies of other Podospora species indicate a few differences in ascocarp formation and perithecial structure in comparison to P. curvicolla. In both P. anserina, studied by Mainwaring and Wilson (1968), and P. arizonensis, researched by Mai (1976), coiled ascogonia and paraphyses were reported, features not observed in Podospora curvicolla. Carr and Olive researched Sordaria fimicola in 1957 and they reported that the developemnt of the ascocarp of S. fimicola showed distinct similarities to that of P. anserina and P. arizonensis, this includes the formation of a coiled ascogonium and paraphyses. Thus, it is the first stage of ascocarp development in P. anserina, P. arizonensis and S. fimicola that differs significantly from P. curvicolla. Another major difference is the presence of paraphyses in P. anserina, P. arizonensis and S. fimicola, which are lacking in P. curvicolla. The later development of the young perithecium appears to be essentially the same in all three species of Podospora and in S. fimicola.

P. curvicolla follows closely the characteristics outlined for the Diaporthe type centrum. The distinctive ascocarp formation, presence of a pseudoparenchymatous centrum, formation of a perithecial wall and the eventual basal location of the ascogenous tissue provides adequate reasoning for assigning P. curvicolla to the Diaporthe centrum type. It should be noted that Mainwaring and Wilson (1968) treated P. arizonensis as having a Diaporthe centrum type while Mai (1976) considered P. anserina as an intermediate between the Diaporthe and Xylaria centrum types. As reported by Luttrell (1951), S. fimicola is also assigned to the Diaporthe centrum type.

Ascus development in P. curvicolla appears to closely follow that reported in other Podospora species studied. The asci develop from typical croziers and after growth occupy a large portion of the mature centrum.

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