Location: Sunflower and Plant Biology Research2008 Annual Report
1a. Objectives (from AD-416)
1. Collect and evaluate wild and interspecific germplasm for useful agronomic traits. 2. Introgress useful genes into cultivated sunflower through interspecific hybridization and release the enhanced germplasm. 3. Develop DNA markers and apply them to genetic studies and marker-assisted selection.
1b. Approach (from AD-416)
We will collect nine underrepresented wild Helianthus species to fill gaps in the sunflower collection. Wild species will be evaluated for various agronomic traits, such as insect and disease resistance, saturated fatty acid content, cytoplasmic male sterility, and fertility restoration. DNA markers will be identified and used to reveal genetic diversity in the wild Helianthus collection. Once useful germplasm is identified, we will introgress the genes of interest into cultivated sunflower through interspecific hybridization. We will concentrate on transfer of Sclerotinia head and stalk rot resistance genes from wild perennial species into cultivated sunflower. Other traits we will identify and transfer are resistance to sunflower rust, downy mildew, and insects. Additional EST-based and SNP DNA markers will be developed for further saturation of the sunflower genetic map, and markers tightly linked to traits such as resistance to downy mildew, rust, and Sclerotinia, as well as to fertility restoration, will be used to expedite the process of sunflower germplasm enhancement via marker-assisted selection. We will use association mapping to identify DNA markers associated with insect resistance. BAC and BIBAC clones will be used to identify trisomics for the purpose of assigning individual linkage groups of the sunflower genetic map to single chromosomes of cultivated sunflower.
3. Progress Report
Field experiments in 2008 were conducted to confirm previously identified sunflower chromosomal gene locations that contribute to Sclerotinia disease resistance. Promising Sclerotinia-resistant interspecific germplasms based on five annual and two perennial wild species, which had been evaluated in 2007 for Sclerotinia head and stalk rot in field nurseries, were retested in field nurseries in 2008. Fifteen interspecific germplasms were tested that had Sclerotinia head rot infection levels lower than the resistant check in 2007, and 20 germplasms were evaluated that had stalk rot resistance lower than the resistant check in 2007. The project on Sclerotinia resistance germplasm development utilizing wild perennial Helianthus species continued. BC1F3 families, backcrossed with head rot tolerant HA 441, of crosses between NMS HA 89 with head rot resistant accessions H. maximiliani and H. nuttallii are currently being evaluated in field trials. Crosses between NMS HA 89 and stalk rot resistant H. maximiliani, H. giganteus, and H. grosseserratus were backcrossed with stalk rot tolerant line HA 410 and BC1F1 progenies were self-pollinated. Crosses between HA 410 and stalk rot resistant H. californicus were backcrossed with HA 410 three times, and will provide BC4F3 families for the 2009 field evaluation. Crosses of interspecific amphiploids with stalk rot tolerant line HA 410 were advanced to the BC2F2 and BC3F1 generation, and BC2F3 families will be developed for 2009 field tests. Linkage-group-specific BAC clones were identified using overgo hybridization. The utilization of the BAC-FISH technique to identify individual chromosomes is progressing well, and will be used to identify and establish trisomics genetic stocks in the background of P21 and HA 89. In cooperation with Spain on Orobanche resistance, a new resistance source identified in Spain was crossed and backcrossed with a cultivated line in Fargo, and progenies will be evaluated in Spain. In cooperation with the Liaoning Academy of Agricultural Sciences, Shenyang, Liaoning, China, a fertility restorer gene Rf for a new cms derived for H. tuberosus has been identified in an amphiploid involving H. angustifolius, and was successfully transferred into the cms cytoplasm. Inheritance study of the Rf gene is in progress. The integration of classical genes onto the molecular map is in progress. We completed the mapping of the newly identified Rf4 gene for cms GIG2 cytoplasm, a major gene locus HAR-5 conferring resistance to predominant North American downy mildew races, the fertility restoration gene Rf3 in RHA 280, and one vigor restoration gene restoring the vigor reducing effect of perennial Helianthus species cytoplasm. Mapping of one vigor restoration gene from H. giganteus and one recessive white-cotyledon gene is in progress. (This research addresses National Program 301 Action Plan Component 2, Crop Informatics, Genomics, and Genetic Analyses, Problem Statement 2C, Genetic Analyses and Mapping of Important Traits; and Component 3, Genetic Improvement of Crops, Problem Statement 3B, Capitalizing on Untapped Genetic Diversity).
5. Significant Activities that Support Special Target Populations