Submitted to: Canadian Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2006
Publication Date: 9/20/2006
Citation: Inderbitzin, P., Berbee, M., Shoemaker, R., Oneill, N.R., Turgeon, G. 2006. Systematics and mating systems of two fungal pathogens of opium poppy: the heterothallic crivellia papaveracea with a brachycladium penicillatum asexual state and a homothallic species with a b. papaveris asexual state. Can. J. Bot. 84:1304-1326.
Interpretive Summary: Pleospora species belong to a very important class of fungi, many of which are serious agricultural pests that attack and cause yield loss in numerous crops, including fruit trees, vegetable crops, alfalfa, clover, and opium poppy. Increased knowledge of the organisms that cause these diseases can reduce losses and increase yield in desirable crops, and may provide valuable bio-control tools for control of illicit opium poppy production. The taxonomy of fungi attacking opium poppy has historically been very uncertain. Using molecular tools, we discovered and described two of the species that that attack poppy. This research will be useful to scientists concerned with reduction of illicit opium poppy production, as well as to breeders and companies who cultivate opium poppy for production of pharmaceutical products. The research will also benefit scientists concerned with determining the cause of diseases.
Technical Abstract: This paper presents a systematic revision of the fungal opium poppy pathogens formerly known as Pleospora papaveracea, along with allied asexual states formerly placed in Dendryphion. The revision is based on analysis of phylogenetic relationships, comparative morphology, and analysis of mating systems. Using morphology and 18S and ITS rDNA, we established that these species belonged to the Alternaria clade rather than to Pleospora, a conclusion supported by the Shimodaira-Hasegawa Test. For these fungi, we erected the new genus Crivellia, with Crivellia papaveracea as type. ITS rDNA analyses suggested with moderate support A. brassicicola, A. japonica and Ulocladium alternariae as Crivellia’s closest relatives. Combined ITS, partial GPD and EF-1 alpha analyses confirmed earlier studies showing that asexual isolates in the Crivellia lineage of poppy pathogens represent two closely-related species. Because Dendryphion was polyphyletic, the former genus Brachycladium was resurrected for B. penicillatum and B. papaveris, the Crivellia asexual states that had been in Dendryphion. Molecular and morphological comparison with isolates from field-collected ascomata and morphological comparison with the type specimen of P. papaveracea indicated that B. penicillatum and not B. papaveris was the anamorph of C. papaveracea. The mycelia from single conidial or single ascospore isolates, including mycelia from 14 single ascospores from one field-collected C. papaveracea ascoma, either had a MAT1-1 or MAT1-2 gene and were thus heterothallic. In contrast, each single-conidial isolate of B. papaveris had an incomplete MAT1-2 gene fused to a MAT1-1 region and was inferred to be homothallic. We speculate that ancestral MAT fusion might have led to speciation in Crivellia.