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- Title
Neurospora tetrasperma crosses heterozygous for hybrid translocation strains produce rare eight-spored asci-bearing heterokaryotic ascospores.
- Authors
Kasbekar, Durgadas; Rekha, Selvam
- Abstract
During ascogenesis in Neurospora, the ascospores are partitioned at the eight-nucleus stage that follows meiosis and a post-meiotic mitosis, and the ascospores that form in eight-spored asci are usually homokaryotic. We had previously created novel T strains by introgressing four Neurospora crassa insertional translocations (EB4, IBj5, UK14-1, and B362i) into N. tetrasperma. We now show that crosses of all the T strains with single-mating-type derivatives of the standard N. tetrasperma pseudohomothallic strain 85 (viz. T a × 85 A or T A × 85 a) can produce rare eight-spored asci that contain heterokaryotic ascospores, or ascospores with other unexpected genotypes. Our results suggest that these rare asci result from the interposition of additional mitoses between the post-meiotic mitosis and the partitioning of nuclei into ascospores, leading to the formation of supernumerary nuclei that then generate the heterokaryotic ascospores. The rare asci probably represent a background level of ascus dysgenesis wherein the partitioning of ascospores becomes uncoupled from the post-meiotic mitosis. Ordinarily, the severest effect of such dysgenesis, the production of mating-type heterokaryons, would be suppressed by the N. crassa tol ( tolerant) gene, thus explaining why such dysgenesis remained undetected thus far.
- Subjects
NEUROSPORA tetrasperma; CHROMOSOMAL translocation; ASCOSPORES; MITOSIS; HETEROZYGOSITY
- Publication
Journal of Biosciences, 2017, Vol 42, Issue 1, p15
- ISSN
0250-5991
- Publication type
Article
- DOI
10.1007/s12038-017-9671-z