Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/25/2008
Publication Date: 2/25/2008
Publication URL: www.sunflowernsa.com/research/research-workshop/documents/Feng_etal_StalkRot_08.pdf
Citation: Feng, J., Seiler, G.J., Gulya, T.J., Cai, X., Jan, C.C. 2008. Incorporating Sclerotinia stalk rot resistance from diverse perennial wild Helianthus species into cultivated sunflower. 30th Sunflower Research Workshop, National Sunflower Association, January 10-11, 2008, Fargo, ND. Available: http://www.sunflowernsa.com/research/research-workshop/documents/Feng_etal_StalkRot_08.pdf Interpretive Summary: In sunflower, Sclerotinia stalk and head rot caused serious economic loss for more than 50 percent of the seed yield. Cultivated sunflower lacks resistance to Sclerotinia, although some differences in susceptibility exist. However, the over 51 species of Helianthus, consisting of diploid, tetraploid and hexaploid, represent a diverse potential source of Sclerotinia resistance genes. Since 2005, a program focusing on the transfer of Sclerotinia stalk rot resistance from wild Helianthus species of different ploidploidy levels (2x, 4x, 6x) into adapted sunflower germplasm via interspecific hybridization was started at the Sunflower Research Unit in Fargo. Selected wild species accessions were evaluated in the greenhouse or in the field and were shown to possess high levels of resistance to Sclerotinia stalk rot. We summarized our progress during the past three years utilizing different resistance sources.
Technical Abstract: Evaluation of the wild sunflower germplasms indicated that most perennial wild species, including diploid, tetraploid and hexaploid, possess high level of resistance to Sclerotinia stalk rot. Selected resistant wild species were crossed with cultivated sunflower to transfer Sclerotinia resistance genes, though the frequency of successful crosses was relatively low. Hexaploid H. californicus was crossed with HA 410, a moderatly stalk rot tolerant inbred line, and repeatedly backcrossed to BC4F1 from 2005 to 2007, with an accompanying chromosome number reduction from 2n=68 of the F1 hybrid to 2n=34 in the BC4F1. Accordingly, pollen fertility was increased from 4.6% (BC1F1), 31.3% (BC2F1), 38.5% (BC3F1) to 73.9% in BC4F1 generation, and the corresponding seed set for BC1F1, BC2F1, BC3F1, and BC4F1 were 0.05%, 3.35%, 11.9%, and 35.3%, respectively. Currently, of the 79 BC4F1 plants, 14 plants have a chromosome number of 2n=34 and are ready for seed increase for field testing in 2009 and the 23 plants with 2n=35 can be self-pollinated one more time to reach 2n=34. Crosses between five selected interspecific amphiploids and HA 410 were successful obtaining 145 BC2F1 plants. Of these, 47 plants with 2n=34 are available for seed increase for field testing and 50 plants with 2n=35 will be self-pollinated or backcrossed before being increased for field testing. Three perennial diploid species H. maximiliani, H. giganteus, and H. grosseserratus, highly resistant to Sclerotinia stalk rot, were used as pollen donors to cross with NMS HA 89. In total, 67 hybrid seedlings were obtained with all having very low pollen fertility around 1%. All F1 plants were backcrossed with HA 410 in the greenhouse, which resulted in 155 BC1 seeds from 64,618 pollinated florets. Continued backcrossing and self-pollination of 2n=34 progeny plants derived from wild diploid, amphiploid and hexaploid sources will generate a large number of lines for field evaluation for resistance to Sclerotinia stalk rot in 2009.