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United States Department of Agriculture

Agricultural Research Service

Research Project: SUNFLOWER GERMPLASM DIVERSIFICATION AND CHARACTERIZATION UTILIZING WILD SUNFLOWER SPECIES, CYTOGENETICS, AND APPLIED GENOMICS

Location: Sunflower Research

Title: Molecular mapping of R11, a novel rust resistance gene in sunflower (Helianthus annuus L.)

Authors
item QI, LILI
item SEILER, GERALD
item Vick, Brady
item GULYA, THOMAS

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: December 7, 2011
Publication Date: N/A

Interpretive Summary: Sunflower oil provides about 13% of the world’s edible oil. The high proportion of polyunsaturated fatty acids renders sunflower oil as a popular source of essential fatty acids in the diet. However, sunflower production in North America has recently been threatened by the development of new virulent races of sunflower rust. The majority of commercial hybrids are susceptible to the new predominant and virulent races. A male-sterile restorer line, Rf ANN-1742, was identified as resistant to the newly emerged rust races. The aim of this study was to elucidate the inheritance of rust resistance and identify the chromosome location of the underlying genes in Rf ANN-1742. Statistical analysis of the segregation of rust response in F2 and F3 populations revealed that rust resistance is controlled by single dominant genes derived from alien segments of Rf ANN-1742. The gene was designated as R11. A set of 723 simple sequence repeat (SSR) DNA markers of sunflower was used to identify polymorphic markers (markers that are different) between HA 89 and the resistant plant. We used the polymorphic markers together with a technique called bulk segregant analysis to map the rust gene to linkage group (LG). Based on the SSR analyses of 192 F2 individuals, R11 mapped to the lower end of LG 13 and flanked by ORS728 and ORS45, with a genetic distance of 0.3 cM and 1.0 cM, respectively. R11 is genetically independent from the rust R-genes R1, R2, and R5, but may be closely linked to the rust R-gene Radv derived from wild H. argophyllus, forming a large rust R-gene cluster of Radv/R11/ R4 in the lower end of LG 13. Any combination of the genes R2, R4, and R5 with R11 would give resistance to a majority of rust races and provide protection against the spread of new rust races. The molecular markers closely linked to the different resistance genes should make this task more feasible, and will allow breeders to effectively select disease-resistant progeny in early segregating generations.

Technical Abstract: Sunflower production in North America has recently been threatened by the evolution of new virulent pathotypes of sunflower rust caused by the fungus Puccinia helianthi Schwein. Rf ANN-1742, an ‘HA 89’ backcross restorer line derived from wild annual sunflower (Helianthus annuus L), was identified as resistant to North America rust races 336 (the predominant race over three years) and 777 (the most virulent race). The aim of this study was to elucidate the inheritance of rust resistance and identify the chromosome location of the underlying gene in Rf ANN-1742. The F2 and F2:3 populations derived from a heterozygous rust resistant plant, 09-519-1, selected from Rf ANN-1742 were inoculated with North America rust race 336. A set of 723 mapped SSR markers of sunflower was used to screen the polymorphism between HA 89 and the resistant plant. The bulked segregant analysis was performed to identify the genomic region harboring the rust resistance gene. Chi-squared analysis of rust response segregation in F2 and F3 populations revealed that a dominant gene governs rust resistance in the line Rf ANN-1742 and was designated as R11. Bulked segregant analysis subsequently located R11 on linkage group (LG) 13 of sunflower. Based on the SSR analyses of 192 F2 individuals, R11 was mapped to the lower end of LG13 and flanked by ORS728 and ORS45, with a genetic distance of 0.3 cM and 1.0 cM, respectively. R11 is genetically independent from the rust R-genes R1, R2, and R5, but may be closely linked to the rust R-gene Radv derived from wild H. argophyllus, forming a large rust R-gene cluster of Radv/R11/ R4 in the lower end of LG13. Any combination of the genes R2, R4, and R5 with R11 would give resistance to a majority of rust races and provide protection against the spread of new rust races. The molecular markers closely linked to the R11 gene developed in this study should make this task more feasible, and will allow breeders to effectively select disease-resistant progeny in early segregating generations.

Last Modified: 9/10/2014
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