Prospects for biological control of Cape tulips with a rust fungus

[摘要] This 1-year project aimed to determine the prospects of using the rust fungus Puccinia moraeae for the biological control of one and two-leaf Cape tulips in Australia. A trip was undertaken in the Western Cape Province of South Africa in late winter 2009 to collect accessions of the rust fungus on these two species. The rust fungus was found to be widespread throughout the range of Cape tulips in South Africa, and was most prevalent on two-leaf Cape tulip. Several rust accessions were collected and imported into quarantine in Australia: 6 accessions from one-leaf Cape tulip, 31 from two-leaf Cape tulip and 2 from a mixture of one and two-leaf Cape tulips. One and two-leaf Cape tulip plants, which had been dug up from different sites across southern Australia by collaborators and planted in pots in the glasshouse, were inoculated with each of the rust accessions. Although plants initially appeared in good health, many of them died during the trials, most likely due to transplantation shock. In light of difficulties encountered in producing a continuous supply of Cape tulip plants throughout the year, a trial was initiated to compare the effect of different storage conditions on the ability of corms to produce vigorous plants once planted and will be continued until September 2010.While a few uredinia or telia developed on both Cape tulip species inoculated with some of the imported rust accessions, only one accession (no 8) was successfully cultured and maintained on two-leaf Cape tulip for the duration of the project. Great difficulties however, were encountered in maintaining this rust accession due to the poor quality of plants available during spring and summer, and the tendency of the rust accessions to produce mostly telia and only a few uredinia from which limited amount of spores could be recovered to inoculate new plants. Some of the Australian two-leaf Cape tulip accessions inoculated with this rust accession were found to be resistant, indicating that intraspecific variation in plant resistance exists in this host-pathogen system. Consequently, collaboration with Dr Richard Watts from CSIRO Plant Industry (Canberra) was established to begin exploring possible molecular markers that could be used to determine how many genotypes of one-leaf and two-leaf Cape tulips exist in Australia and to pin point the putative area of origin of Australian Cape tulips in South Africa. A preliminary host-specificity test was also performed with rust accession no 8 using a few key non-target plant species closely related to Cape tulips within the Iridaceae. None of the species inoculated, except the two-leaf Cape tulip plants, developed any uredinia or telia.Recommendations on additional research required to deliver a biological control solution, based on the rust fungus, for Cape tulips in Australia are included and comprise 1) identification of Australian genotypes of Cape tulips, 2) selection of highly pathogenic rust accessions through more collection and screening and 3) comprehensive host-specificity testing with selected rust accessions.

[发布机构] CSIRO

[学科分类] 地球科学(综合)