Title: Evaluation of Wild Helianthus Species for Resistance to Sclerotinia Stalk Rot Authors
Submitted to: ARS Sclerotinia Initiative Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: January 9, 2009
Publication Date: January 21, 2009
Citation: Block, C.C., Gulya Jr, T.J., Marek, L. 2009. Evaluation of Wild Helianthus Species for Resistance to Sclerotinia Stalk Rot [abstract]. In: Proceedings of the ARS Sclerotinia Initiative Annual Meeting, January 21-23, 2009, Bloomington, Minnesota. p. 11. Technical Abstract: The evaluation efforts are focused primarily on the annual diploid Helianthus species in the USDA sunflower germplasm collection. A greenhouse screening method was employed, using soil-applied Sclerotinia-infested millet as inoculum. Greenhouse screening facilitates the rapid evaluation of much larger plant populations than could be managed in field plots. With this approach, much of the susceptible germplasm can be filtered out, making better use of the follow-up field screening trials. In 2008, 255 accessions were evaluated in the greenhouse, including all available accessions of H. argophyllus, H. debilis, H. exilis, H. neglectus, and H. praecox plus 45 accessions of H. annuus. Accessions with superior wilt resistance were identified in all species except for H. exilis. Twenty accessions were selected for a 2008 North Dakota field trial. The entries included susceptible and resistant germplasm from nine H. debilis accessions, three H. argophyllus, six H. annuus and two H. resinosus (perennial) accessions. Extensive flooding killed the H. debilis plants, but data was obtained from most of the other plots. The three most Sclerotinia-resistant entries were two H. resinosus accessions, PI 650079 and PI 650082, both with 100% survival and one H. argophyllus accession, PI 649863, with 94% survival. The resistant check, Croplan 305, had 88% survival while the susceptible check, Cargill 270, had 59% survival. Three of the H. annuus accessions had survival percentages equivalent to Croplan 305, PI 653604 (87%), PI 435434 (86%) and PI 435417 (85%). The excellent wilt resistance (near immunity) confirmed in the hexaploid species Helianthus resinosus deserves further exploration, but genetic incompatibilities may hinder attempts to transfer resistance from this species into cultivated sunflower.