Isolation and characterization of a reciprocal translocation strain T(I;II) KH 5-9, inseparable from morphological mutations near mating type.

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Abstract
A [Neurospora crassa] reciprocal chromosomal translocation strain, T (I;II) KH 5-9, was obtained by spontaneous chromosomal rearrangements. In strains heterozygous for KH 5-9, 50-60% of the ascospores are aborted. The ascus frequencies (black: white) were 27% 8:0, 18% 6:2, 27% 4:4, 9% 2:6 and 14% 0:8. In homozygous strains 0 to 10% of the ascospores were aborted. The strain harbored in the left arm of LG I a chromosomal break point between leu-3 and un-3 very close to ser-3. The resulting left arm of LG I was translocated to the right arm of LG II distal to un-20 at very near position to ace-1. The right arm of LG II was translocated to the left arm of LG I. The direction of chromosomal attachment of LG IL to LG IIR was from arg-12, un-20 (LG IIR), break point, leu-3 and un-5 (LG IL). Strain T (I;II) KH 5-9 was inseparable from morphological mutations designated eas-2 (easily wettable-2) and brm (branched mycelia). Strain with brm was derived from T (I;II) KH 5-9 eas-2 and zygotes between them produced 0-10% of abortive ascospores. Strains with eas-2 form conidia readily soluble to water and strains with brm from aconidial mycelia with defective cell wall. Forced heterokaryon between them formed wild type hydrophobic conidia. In the zygotes between then, brm and eas-2 behaved closely linked to mating type and un-3. From these results KH 5-9 was assumed to harbor one or closely linked 2 mutations in the regulator for eas-2 and brm.