Cytology of the Ascus and Ascocarp Development in Achaetomium Uniapiculatum

Abstract

The paper deals with the development of ascocarp and nuclear behaviour during the development of ascus and ascospores in Achaetomium uniapiculatum. The ascocarp arises by the coiling of a hyphal branch.The septate ascogonial coil soon becomes surrounded by the vegetative hyphae forming a pseudoparenchymatous spherical body which in later stages gets differentiated into wall layers and central sporogenous tissue. The ascus originates from the penultimate cell of the crozier produced by the binucleate ascogenous cells. As in most of the ascomycetes, in A. uniapiculatum also, four divisions follow karyogamy resulting in binucleate ascospores, each mature ascospore only has a single nucleus the other nucleus probably degenerates.The haploid number of chromosome is 5 (n=5).

Cytology of the Ascus and Ascocarp Development inAchaetomiella Megaspora(Sörgel) D. Hawksw

“…The rest of the development of the ascocarp initial into a mature perithecium ) is similar to that reported for Achaetomium uniapiculatum (RAI and CHOWDHERY 1973), Achaetomiella virescens (RAI et al 1979) and Sordaria fimicola (CARR and OLIVE 1958).…”

Ascus cytology and ascocarp development in Achaetomiella virescens.

“…The develop ment of perithecium in Achetomiella is almost similar to that of Achaetomium and Sordaria (Rai andChowdhury 1973, Carr andOlive 1958). In Achaetomiella virescens the ascogonial coil generally originates from a stout, deeply staining multinucleated lateral branch from the basal creeping mycelium and by further elongation it assumes a coiled shape.…”

“…In A. virescens plasmogamy (Fig. 4) occurs after the formation of the first branch and is by the fusion of a hyphal branch from the terminal portion of the inner coil with the other hyphal cell as reported for various other ascomycetes -viz, Achaetomium, Gelasinospora, Neurospora and Sordaria (Rai and Chowdhury 1973, Ellis 1960, Colson 1934, Carr and Olive 1958. From the main hypha the ascogonial hypha originates, and from the basal or lower cells of the ascogonial hyphae arise outgrowths that invest the coil and subsequently develops the pseudo parenchymatous wall of the perithecium.…”