|Gulya Jr, Thomas|
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/5/2007
Publication Date: 2/5/2007
Citation: Feng, J., Seiler, G.J., Gulya Jr, T.J., Jan, C.C. 2007. Advancement of pyramiding new Sclerotinia stem rot resistance genes from H. californicus and H. schweinitzii into cultivated sunflower. 29th Sunflower Research Workshop, January 10-11, 2007, Fargo, ND. Available: http://www.sunflowernsa.com/research/research-workshop/documents/Feng_etal_Pyramid_2007.pdf Interpretive Summary: Sclerotinia sclerotiorum (Lib.) is considered one of the most destructive pathogen for sunflower, which causes white rot and wilt. No complete resistance has been identified in the cultivated sunflower. However, some wild Helianthus species, e.g. Helianthus californicus DC. and H. schweinitzii T and G, are supposed to be potential sources of disease resistance and can be exploited in interspecific crosses to increase the genetic variability of cultivated sunflower. Among USDA released tolerance lines, HA 410 had the lowest percentage of Sclerotinia-infected plants among the eight released Sclerotinia-tolerant lines for stem rot. Therefore, the main objectives of this project were to transfer new resistance genes from these two perennial species into HA 410 and to develop new germplasm lines superior to HA 410. The interspecific hybrids between HA 410 and H. californicus and H. schweinitzii were produced via an embryo rescue technique. Greenhouse evaluation indicated excellent stem rot resistance for interspecific F1 progeny and HA 410. Most F1 progenies had good backcross seed set, but with much lower sib-pollinated seed set. We report here the progress of progenies after one and two backcrosses with the recurrent parent HA 410.
Technical Abstract: Interspecific hybridization of H. californicus and H. schweinitzii with HA 410 was conducted in 2006 based on the BC1F1s obtained in 2005. In total, 109 BC1F1 plants were grown in the greenhouse for backcrossing. Because of unbalanced chromosome numbers in the triploid BC1F1, the BC1F1 pollen fertility ranged from 2.45% to 4.63%, and seed set was very low. In total, 59 BC2F1 seeds were obtained from 136,220 pollinated florets. Based on these results, we are re-crossing the BC1F1 with HA 410 to produce more BC2F1 seeds to screen for stem rot resistance.