title: Quest to elucidate the life cycle of Puccinia psidii sensu lato.
abstract: There is controversy surrounding the described life cycle of the rust fungus Puccinia psidii sensu lato, which causes disease on several plant species in the family Myrtaceae. The objective of this study was to determine whether P. psidii s.l. is autoecious by performing basidiospore inoculations, and microscopically examining the fate of basidiospores on the leaf surface and nuclear condition at different stages of rust development. No spermogonia developed on leaves of Agonis flexuosa inoculated either with a teliospore suspension or basidiospores naturally discharged from telia. Uredinial sori that developed in all three inoculations with teliospore suspensions and in one of the five inoculations with naturally-discharged basidiospores from telia were most likely the result of urediniospore infections. Microsatellite analysis revealed that isolates made from these uredinial sori had the same multilocus genotype as that of the original isolate. No signs of penetration of plant cells by basidiospores were observed on A. flexuosa and Syzygium jambos. The nuclear condition of mycelia of uredinial sori, urediniospores, teliospores, and four-celled metabasidia was typical of that in many rust fungi. Our study could not provide unequivocal proof that P. psidii s.l. is autoecious. While it is possible that it could be heteroecious, with an unknown alternate aecial host, it is also possible that basidiospores have lost the ability to infect Myrtaceae or are infrequently operational.
authors: CSIRO Ecosystem Sciences and Biosecurity Flagship, GPO Box 1700, Canberra, Australian Capital Territory 2601, Australia. Electronic address: louise.morin@csiro.au.
authors: Louise
authors: L
authors: Morin
authors: CSIRO Plant Industry, GPO Box 1600, Canberra, Australian Capital Territory 2601, Australia.
authors: Mark J
authors: MJ
authors: Talbot
authors: Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 98, Hobart, Tasmania 7001, Australia.
authors: Morag
authors: M
authors: Glen
mesh_terms: D001487:Basidiomycota / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D004271:DNA, Fungal / Q000235:genetics; D018895:Microsatellite Repeats; D058889:Molecular Typing; D016533:Mycological Typing Techniques; D027822:Myrtaceae / Q000382:microbiology; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000382:microbiology; D027842:Syzygium / Q000382:microbiology
chemical_list: D004271:DNA, Fungal
keywords: Eucalyptus rust; Guava rust; Myrtle rust; Nuclear cycle; Uredo rangelii