Vegetative incompatibility in the het-6 region of Neurospora crassa is mediated by two linked genes.
Non-self-recognition during asexual growth of Neurospora crassa involves restriction of heterokaryon formation via genetic differences at 11 het loci, including mating type. The het-6 locus maps to a 250-kbp region of LGIIL. We used restriction fragment length polymorphisms in progeny with crossovers in the het-6 region and a DNA transformation assay to identify two genes in a 25-kbp region that have vegetative incompatibility activity. The predicted product of one of these genes, which we designate het-6(OR), has three regions of amino acid sequence similarity to the predicted product of the het-e vegetative incompatibility gene in Podospora anserina and to the predicted product of tol, which mediates mating-type vegetative incompatibility in N. crassa. The predicted product of the alternative het-6 allele, HET-6(PA), shares only 68% amino acid identity with HET-6(OR). The second incompatibility gene, un-24(OR), encodes the large subunit of ribonucleotide reductase, which is essential for de novo synthesis of DNA. A region in the carboxyl-terminal portion of UN-24 is associated with incompatibility and is variable between un-24(OR) and the alternative allele un-24(PA). Linkage analysis indicates that the 25-kbp un-24-het-6 region is inherited as a block, suggesting that a nonallelic interaction may occur between un-24 and het-6 and possibly other loci within this region to mediate vegetative incompatibility in the het-6 region of N. crassa.
Smith
M L
ML
Biology Department, Carleton University, Ottawa, Ontario K1S 5B6, Canada. mysmith@ccs.carleton.ca
Micali
O C
OC
Hubbard
S P
SP
Mir-Rashed
N
N
Jacobson
D J
DJ
Glass
N L
NL
D000483:Alleles; D003001:Cloning, Molecular; D003360:Cosmids / Q000235:genetics; D005800:Genes, Fungal / Q000235:genetics*; D049770:Genes, Mating Type, Fungal; D008040:Genetic Linkage / Q000235:genetics*; D005819:Genetic Markers; D009492:Neurospora crassa / Q000235:genetics* / Q000254:growth & development; D016366:Open Reading Frames / Q000235:genetics; D020161:Physical Chromosome Mapping; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D005819:Genetic Markers