SUNFLOWER GERMPLASM DIVERSIFICATION AND CHARACTERIZATION UTILIZING WILD SUNFLOWER SPECIES, CYTOGENETICS, AND APPLIED GENOMICS
Location: Sunflower Research
Title: Transferring Sclerotinia Resistance Genes from Wild Helianthus Species into Cultivated Sunflower
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 12, 2010
Publication Date: March 12, 2010
Citation: Liu, Z., Cai, X., Seiler, G.J., Gulya, T.J., Rashid, K.Y., Jan, C. 2010. Transferring Sclerotinia Resistance Genes from Wild Helianthus Species into Cultivated Sunflower. 32nd Sunflower Research Workshop, January 13-14, 2010, Fargo, ND. Available: http://www.sunflowernsa.com/research/research-workshop/documents/Liu_ResistanceGenes_10%20.pdf
Interpretive Summary: Sclerotinia attacks sunflower causing root, stalk, and head rot, and is considered one of the most damaging sunflower diseases. Genetic analysis has indicated that Sclerotinia resistance is multigenic, and that resistance to basal stalk and head rot are not related, thus requiring independent screening procedures for each type of infection. Cultivated sunflower lacks a sufficient level of resistance to both Sclerotinia stalk and head rot, while an abundance of resistance has been confirmed in perennial Helianthus species. The objective of this project was to transfer of Sclerotinia head and stalk rot resistance genes from wild perennial hexaploid, diploid Helianthus accessions, and interspecific amphiploids into cultivated sunflower. Interspecific hybrids were produced between stalk rot resistant wild Helianthus sources and cultivated line and continued backcrossing with HA 410 and selfing resulted in progeny plants with improved pollen and seed fertility and with 2n chromosome numbers the same as that of the cultivated sunflower. For head rot, crosses between NMS HA89 and head rot resistant H. maximiliani and H. nuttallii were backcrossed with HA 441 and progeny seeds increased in 2008. Replicated field tests with 163 and 316 progeny families were screened for head and stalk-rot resistance in 2009, respectively. The results indicated moderate to good resistance, suggesting successful gene introgression. Molecular tracking studies using SSR markers indicated high polymorphism between wild resistant donors and the cultivated recurrent parents, and the retention of markers specific to resistant donors was higher for progenies from diploid perennials than from hexpaloid or interspecific amphiploids, suggesting a higher frequency of gene introgression when perennial diploids species were used. Protocol of genomic in situ hybridization (GISH) distinguishing chromosomes of perennial Heliathus species and cultivated sunflower has been established, providing an additional tool for studying gene transfer.
Eight Sclerotinia-resistant diploid accessions, one hexaploid, and five interspecific amphiploids have been successfully crossed with Sclerotinia-tolerant cultivated lines, backcrossed and selfed to produce progeny families for field evaluation. In 2009, replicated field screening of 163 and 316 progeny families for head and stalk rot resistance, respectively, indicated good-to-excellent resistance among the progeny families suggesting successful gene introgression. A protocol using genomic in situ hybridization (GISH) to distinguish between chromosomes of perennial Helianthus species and cultivated sunflower has been established providing a new tool for studying gene transfer. A molecular tracking study utilizing SSR markers indicated a higher frequency of gene introgression from diploid perennials than from hexaploid or interspecific amphiploids, suggesting an advantage in using diploid perennials.