A mating-type factors of Coprinus cinereus have variable numbers of specificity genes encoding two classes of homeodomain proteins.
We have identified the seven genes that constitute the A43 mating-type factor of Coprinus cinereus and compare the organisation of A43 with the previously characterised A42 factor. In both, the genes that trigger clamp cell development, the so-called specificity genes, are separated into alpha and beta loci by 7 kb of noncoding sequence and are flanked by homologous genes alpha-fg and beta-fg. The specificity genes are known to encode two classes of dissimilar homeodomain (HD1 and HD2) proteins and have different allelic forms which show little or no cross-hybridisation. By partial sequencing we identified a divergently transcribed HD1 (a1-2) and HD2 (a2-2) gene in the A43 alpha locus. a2-2 failed to elicit clamp cell development in three different hosts, suggesting that it is non-functional. a1-2 elicited clamp cells in an A42 host that has only an HD2 gene (a2-1) in its alpha locus, thus demonstrating that the compatible A alpha mating interaction is between an HD1 and an HD2 protein. The A43 beta locus contains three specificity genes, the divergently transcribed HD1 and HD2 genes b1-2 and b2-2 and a third HD1 gene (d1-1) that was shown by hybridisation and transformation analyses to be functionally equivalent to d1-1 in A42. An untranscribed footprint of a third A42 HD1 gene, c1-1, was detected between the A43 b2-2 and d1-1 genes by Southern hybridisation.
Department of Plant Sciences, University of Oxford, UK.
U
U
Kües
A M
AM
Tymon
W V
WV
Richardson
G
G
May
P T
PT
Gieser
L A
LA
Casselton
D000595:Amino Acid Sequence; D003302:Coprinus / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D018398:Homeodomain Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D012331:RNA, Fungal / Q000235:genetics; D014170:Transformation, Genetic
D005656:Fungal Proteins; D018398:Homeodomain Proteins; D012331:RNA, Fungal