Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/5/2007
Publication Date: 2/5/2007
Citation: Jan, C.C., Feng, J., Seiler, G.J., Rashid, K.Y. 2007. Development of Sclerotinia head rot resistant germplasm utilizing H. maximiliani and H. nuttallii. 29th Sunflower Research Workshop, January 10-11, 2007, Fargo, ND. Available: http://www.sunflowernsa.com/research/research-workshop/documents/Jan_etal_Germplasm_2007.pdf Interpretive Summary: Sclerotinia is the most damaging disease of sunflower with an incidence higher than other major sunflower diseases surveyed. Wild Helianthus species have played an important role in establishing sunflower as an important global oil crop. However, the present day sunflower germplasm is still represented by a relatively narrow genetic base, limiting its future success as a competitive major oilseed crop. Of the 51 sunflower species, the 27 diploid perennial species are difficult to hybridize with cultivated sunflower, often they produce sterile F1 plants, and represent a significant amount of unexplored genetic variation for sunflower improvement. A total of 18 H. maximiliani and H. nuttallii accessions highly resistant to Sclerotinia head rot was identified by Rashid and Seiler. These lines are expected to possess new resistance genes for Sclerotinia head rot, and are expected to provide alternative means of gene transfer different from transferring genes from polyploid Helianthus species or interspecific amphiploids.
Technical Abstract: Interspecific hybridization of NMS HA 89 with Sclerotinia head rot resistant wild diploid perennial H. maximiliani and H. nuttallii accessions was successful using embryo rescue. A total of 162 F1 hybrid plants were obtained after rescuing 228 embryos from 70,500 pollinated florets. Most F1 plants had the expected 2n chromosome number of 34. A few F1 hybrids had a 2n=51 chromosome number which was assumed to have resulted from fertilization of normal gametes with unreduced gametes. Most F1 plants with the 2n=34 chromosome number had low pollen stainability of around 1%, and consequently low backcross seed set with only 85 seeds from 506 pollinated heads. Backcrosses of 2n=34 F1 plants with HA 441 produced BC1F1 progeny with 2n=34 or 35 chromosomes. Sib-pollination among heads with colchicine-induced chromosome doubling also had low seed set with 250 seeds from 425 pollinated heads producing amphiploids with 2n=62 to 68 chromosomes. Backcrossing of 2n=34 to 35 F1 plants with HA 441 is now in progress, as well as sib-pollination of the amphiploids for seed increase.