Submitted to: Germplasm Release
Publication Type: Germplasm Release
Publication Acceptance Date: 10/11/2004
Publication Date: 10/11/2004
Citation: Block, C.C. 2004. 200x. Notice of release of two multiple disease-resistant sunflower germplasms, sam-1 and sam-2. Germplasm Release.
Interpretive Summary: This is a germplasm release, no interpretive summary required.
Technical Abstract: Two sunflower populations with multiple disease resistance were developed and made available as germplasm releases. Populations SAM-1 and SAM-2 were developed from wild Helianthus annuus germplasm by recurrent selection for resistance to three fungal diseases: Alternaria leaf blight, caused by Alternaria helianthi, Septoria leaf blight caused by Septoria helianthi, and powdery mildew, caused by Erysiphe cichoracearum. Accessions used as parents for SAM-1 and SAM-2 represented the most disease resistant available from 220 wild accessions originally tested. Twenty-eight accessions were pooled as the parent set for SAM-1 and 32 accessions were pooled for SAM-2. Superior plants were selected and allowed to inter-pollinate in each of four years for SAM-1 and three years for SAM-2. Resistance was characterized by hypersensitive spots or flecks on leaves or by small leaf spots showing little of the yellowing, death, and leaf drop normally seen with susceptible plants. Powdery mildew was not inoculated, but natural infection was common and susceptible plants were eliminated. These populations offer potential sources of genes for disease tolerance or resistance not currently found in cultivated sunflowers. They are available for use by industry and public researchers to create parental lines or germplasm with improved disease resistance. These lines may be of particular value in tropical or subtropical regions where Alternaria and Septoria leaf blights limit sunflower production.