diploid ascospores

locus: Dip

locus_name: diploid ascospores

organism_type: B

chromosome_number: III

chromosome_side: R

link_group: IIIR

cultural_requirements: IIIR. Between ro-2 (7%) and phe-2 (1%). The mutant is vegetatively indistinguishable from wild type. Crosses heterozygous for Dip-1 typically give about two-thirds abnormal asci, most commonly with four ascospores but not uncommonly with eight. Other asci have three spores, or two, or one giant spore. The ascospores in asci with fewer than four spores are often misshapen and usually do not germinate. Surprisingly, Dip ´ Dip crosses give almost entirely eight-spored asci. Hence, Dip is not simply ascus-dominant in the usual sense. Spores from eight-spored asci are always haploid, and the Dip segregants can only be identified by progeny testing. Individual spores from four-spored asci generally give rise to cultures that are self-fertile because they are heterozygous or heterokaryotic for mat. When a four-spored ascus is heterozygous for multiple markers, a germinated ascospore gives rise to a culture in which the diploidy quickly breaks down, resulting in a complex heterokaryon. Many kinds of mitotic segregants can be isolated from the conidia of such a culture. Cytologically, the nuclei giving rise to ascospores are clearly of higher ploidy than haploid, but the exact number of chromosomes cannot be distinguished. Crosses to Dip can shelter sexually lethal mutant genes such as Asm-1 and enable them to be recovered from crosses.

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Strains

FGSC #	Reporting Genes	Species
FGSC #9536	Dip	Neurospora crassa
FGSC #9537	Dip	Neurospora crassa

References

Authors	Title	Year