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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower and Plant Biology Research » Research » Publications at this Location » Publication #319722
Title: Molecular mapping of a rust resistance gene R14 in cultivated sunflower line PH 3

Author
item ZHANG, MING - Heilongjiang Bayi Agricultural University (HLAU)
item LIU, ZHAO - North Dakota State University
item Jan, Chao-Chien

Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2016
Publication Date: 3/4/2016
Citation: Zhang, M., Liu, Z., Jan, C. 2016. Molecular mapping of a rust resistance gene R14 in cultivated sunflower line PH 3. Molecular Breeding. 36:32. doi:10.1007/s11032-016-0456-0.

Interpretive Summary: Sunflower rust, caused by the fungus Puccinia helianthi is one of the most serious diseases of cultivated sunflower. Currently only a few commercial hybrids have effective rust resistance genes (R-genes), with the majority of the hybrids susceptible to the newly emerged virulent rust races. Wild sunflower species are very useful sources for rust R-gene discovery and utilization. Germplasm PH 3 originated from the common wild annual sunflower that has resistance to 11 rust races, including the most common and the most virulent race. PH 3 also has a purple hypocotyl color. A close association between rust resistance and the purple hypocotyls was observed in PH 3. The objectives of this study were to genetically map both the rust R-gene, designated R14, and the purple hypocotyl color gene, designated PHC, in PH 3, and to provide useful markers for marker-assisted breeding for sunflower rust resistance. Polymorphic primers were used to identify markers potentially linked to rust resistance and hypocotyl color. The R14 gene was mapped on linkage group 11 with 12 microsatellite markers and one insertion-deletion marker covering a genetic distance of ¬¬16.6 cM. A dominant-repulsion marker was the closest marker at a distance of 1.3 cM, and another co-dominant marker was linked at 2.9 cM proximally. The PHC gene was also linked to R14 gene with a distance of 5.5 cM. Segregation distortion was observed for the R14 and PHC genes, and nine linked markers. The closely linked molecular or morphological markers will be useful for removing susceptible plants at the seedling stage and facilitate sunflower rust resistance breeding.

Technical Abstract: Sunflower, the fifth largest oilseed crop in the world, plays an important role in human diets. Recently, sunflower production in North America has suffered serious yield losses from newly evolved races of sunflower rust (Puccinia helianthi Schwein.). The rust resistance gene, designated R14, in a germplasm line PH 3 originated from a wild Helianthus annuus L. population resistant to 11 rust races. PH 3 has seedling with an extraordinary purple hypocotyl color. The objectives of this study were to map both the R14 rust resistance gene and the purple hypocotyl gene designated PHC in PH 3, and to identify molecular markers for marker-assisted breeding for sunflower rust resistance. A set of 515 mapped sunflower SSR markers was used to detect polymorphisms between the susceptible and resistant parents. Thirteen markers covering a genetic distance of ¬¬16.6 cM on linkage group (LG) 11 were linked to R14. R14 was mapped to the middle of the LG, with a dominant-repulsion marker ORS1227 as the closest marker at a distance of 1.3 cM, and another co-dominant marker ORS542 linked at 2.9 cM proximally. One dominant marker ZVG53 was linked on the distal side at 6.9 cM. The PHC gene was also linked to R14 with a distance of 5.5 cM. Chi-square analysis of the segregation ratios of R14, PHC, and nine linked markers indicated a deviation from an expected 1:2:1 or 3:1 ratio. The closely linked molecular or morphological markers could facilitate sunflower rust resistant breeding and accelerate the development of rust-resistant hybrids.