SUNFLOWER GERMPLASM DIVERSIFICATION AND CHARACTERIZATION UTILIZING WILD SUNFLOWER SPECIES, CYTOGENETICS, AND APPLIED GENOMICS
Location: Sunflower Research
Title: Molecular mapping of the Rf3 fertility restoration gene to facilitate its utilization in breeding confection sunflower
Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 21, 2010
Publication Date: February 11, 2012
Citation: Liu, Z., Mulpuri, S., Feng, J., Vick, B.A., Jan, C. 2012. Molecular mapping of the Rf3 fertility restoration gene to facilitate its utilization in breeding confection sunflower. Molecular Breeding. 29:275-284.
Interpretive Summary: Cytoplasmic male sterility (CMS) is the result of aberrant mitochondrial genes that prevent pollen development. Nuclear fertility restoration (Rf) genes in fertility restorer lines compensate the CMS gene effects and thus produce a male-fertile phenotype. Because no emasculation is needed and self-pollination is eliminated, the combination of CMS and the corresponding Rf genes is a critical tool in large-scale hybrid seed production of many crops. For sunflower, CMS PET1 originated from wild Helianthus petiolaris subsp. petiolaris Nutt. which has been widely used for commercial hybrid seed production since it was discovered in 1969. Rf1 is the dominant nuclear fertility restoration gene widely used for commercial sunflower hybrid production. The single dominant fertility restoration gene Rf3 in confection sunflower line RHA 280 was confirmed to be different from the Rf1, which can restore CMS PET1 as effective as Rf1. The Rf3 has the potential to diversify the fertility restoration genes of sunflower hybrid production, but has been under-utilized for sunflower breeding because of the popularity of Rf1. This research mapped the Rf3 gene, using an F2 population derived from CMS HA 89-3149 x RHA 280, to linkage group 7 of a SSR map. This is the first time a fertility restoration gene in confection sunflower has been mapped. The closely linked marker ORS328 will provide a necessary tool to faciltate its utilization in marker-assisted selection and likely improve its acceptance by the sunflower industry.
The inheritance of a previously identified dominant Rf gene in confection line RHA 280 has been determined and designated as Rf3. This study reports the mapping of the Rf3 locus using an F2 population of 227 individuals derived from CMS HA 89-3149 x RHA 280. Bulked segregant analysis with 624 pairs of simple sequence repeat (SSR) primers and sequence tagged sites (STS) primers identified two polymorphic SSR markers of each linkage group (LG) 7 and LG 11 from a previous map. Results on 90 F2 individuals with 42 polymorphic markers of LGs 7 and 11 indicated that the Rf3 gene was linked with eight markers on LG 7, including five SSR markers (ORS328, ORS331, ORS928, ORS966, and ORS1092) and three expressed sequence tag (EST)-SSR markers (HT619-1, HT619-2, and HT1013). Further analysis of the total F2 population of 227 individuals identified a co-dominant marker, ORS328, linked to Rf3 at a genetic distance of 0.7 cM on one side, a female-dominant marker HT1013 at 12.6 cM proximal to Rf3, and a genetic distance of 47.1 cM for LG 7 was covered. This is the first report of an Rf gene from confection sunflower. The closely linked marker to Rf3 will facilitate marker-assisted selection, and provide a basis for cloning of this gene.