Theoretical and Applied Genetics (2015) 128, 477-488

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L.L. Qi, G.J. Ma, Y.M. Long, B.S. Hulke, L. Gong and S.G. Markell (2015)
Relocation of a rust resistance gene R 2 and its marker-assisted gene pyramiding in confection sunflower (Helianthus annuus L.)
Theoretical and Applied Genetics 128 (3), 477-488
Abstract: Due to the frequent evolution of new pathogen races, sunflower rust is a recurring threat to sunflower production worldwide. The inbred line Morden Cross 29 (MC29) carries the rust resistance gene, R 2 , conferring resistance to numerous races of rust fungus in the US, Canada, and Australia, and can be used as a broad-spectrum resistance resource. Based on phenotypic assessments and SSR marker analyses on the 117 F2 individuals derived from a cross of HA 89 with MC29 (USDA), R 2 was mapped to linkage group (LG) 14 of the sunflower, and not to the previously reported location on LG9. The closest SSR marker HT567 was located at 4.3 cM distal to R 2 . Furthermore, 36 selected SNP markers from LG14 were used to saturate the R 2 region. Two SNP markers, NSA_002316 and SFW01272, flanked R 2 at a genetic distance of 2.8 and 1.8 cM, respectively. Of the three closely linked markers, SFW00211 amplified an allele specific for the presence of R 2 in a marker validation set of 46 breeding lines, and SFW01272 was also shown to be diagnostic for R 2 . These newly developed markers, together with the previously identified markers linked to the gene R 13a , were used to screen 524 F2 individuals from a cross of a confection R 2 line and HA-R6 carrying R 13a . Eleven homozygous double-resistant F2 plants with the gene combination of R 2 and R 13a were obtained. This double-resistant line will be extremely useful in confection sunflower, where few rust R genes are available, risking evolution of new virulence phenotypes and further disease epidemics.
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Link to article at publishers website
Database assignments for author(s): Samuel G. Markell

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Puccinia helianthi Sunflower (Helianthus annuus)