VEGETATIVE INCOMPATIBILITY IN PHOMOPSIS FROM ELM

Antagonistic interactions in the form of narrow, black ‘zone-lines’ were observed between paired cultures of elm Phomopsis. Antagonism occurring between the two previously described morphological ‘groups’ of elm Phomopsis was interpreted as inter-specific antagonism, whereas that within each group was intra-specific. Within group one Phomopsis, which had a dimictic mating system, antagonism was very common between isolates from natural populations and between siblings derived from single ascospores. This suggested that several loci were involved. Antagonism was not a sterility barrier and the mating-type locus did not cause vegetative incompatibility. Group two Phomopsis, which was self-fertile, contained a smaller number of v-c types and its siblings intermingled. © 1990, British Mycological Society. All rights reserved.