Meiosis in Neurospora crassa. II. Isolation and partial characterization of dominant meiotic mutants constituting meiotic gene cluster, V-2 on LG V.

Abstract

Out of 85 dominant meiotic mutants, 10 mutations on LG V localized distal to his-1 were partially characterized.Of these, Asc(KH2B97), Asc (KH 2 B 380), Asc (KH 2 B 658) and Asc (KH 2 B 761) were closely linked to al-3. Asc(KH 2 B 380) and Asc(KH2 B 761) showed reduced recombination recovery rates and Asc (KH2 B 761) elevated recombination frequency between al-3 and ml 10-times higher than that observed in wild type. Though Asc(KH 2 B 97) and Asc(KH 2 B 761) produced aborted ascospores only when they were protoperithecial parents (class I), Asc (KH 2 B 380) and Asc (KH 2 B 761) were class II which produced aborted ascospores independent of protoperithecial or conidial parent. Asc(KH2 B 658) was marginally sensitive to UV compared with that of a Mei-2 strain (FGSC 2621). From these results, these four strains and Asc(KH2 A 83) (Furukawa and Hasunuma 1984) were assumed to be derived from different genes and constituted meiotic gene cluster, designated V-2. Asc (KH 2 B 36), Asc (KH 2 B 146) and Asc (KH 2 B 551) were mapped within relatively small area, putatively from met-3 to ad-7. Asc (KH 2 B 1146) showed elevated recombination frequency between al-3 and ml, Asc(KH 2 B 36) showed class I and Asc(KH2 B 551) showed class II phenotype.Asc(KH 2 B 229), Asc(KH 2 B 300) and Asc(KH 2 B 630) were mapped at a more distal part of ml. Asc(KH 2 B 229) showed class II and Asc(KH 2 B 300) showed class III phenotype. Homozygous zygote of Asc(KH 2 B 300) showed reduced ascospore abortion and it was suggested to be a spore killer. Asc (KH 2 B 229) and Asc (KH 2 B 630) showed marginal sensitivity to UV compared with that of a Mei-2 strain.