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MARKER ASSISTED SELECTION

MARKER ASSISTED SELECTION. PLANT GENETICS RECITATION March 8 th 2012. Why marker assisted selection?. MARKER ASSISTED SELECTION. Individuals carrying the trait of interest are selected based on a marker which is linked to the trait and not on the trait itself. Indirect selection.

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MARKER ASSISTED SELECTION

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  1. MARKER ASSISTED SELECTION PLANT GENETICS RECITATION March 8th 2012

  2. Why marker assisted selection?

  3. MARKER ASSISTED SELECTION • Individuals carrying the trait of interest are selected based on a marker which is linked to the trait and not on the trait itself. • Indirect selection. • Useful when the trait is difficult to measure, and/or is evident only at late developmental stages.

  4. Winter Facult. Spring Harrington Kompolti Triumph 88Ab536 Tremois Dicktoo Strider OSU11 Morex Nure Igri ZCCT-H HvSnf2

  5. I I I K I K I I K iBison 1H+4H+5H Kurtford

  6. The barley stripe rust resistance story ~ 1987

  7. BARLEY STRIPE RUST www.barleyworld.org

  8. BARLEY STRIPE RUST • Caused by fungus Puccinia striiformis f. sp. hordei • Common in Mexico and South America but usually not in Oregon. • It first appeared in the US in 1991 • When infection is severe, losses of 50% are common

  9. BARLEY STRIPE RUST • Resistant cultivars are available • It is necessary to develop resistant cultivars adapted to different barley growing areas • Resistance to the disease is a quantitative trait (non-Mendelian inheritance) • Three Quantitative Trait Loci (QTL) for stripe rust resistance have been mapped and their effects validated. • There are molecular markers located in the target regions of the three QTL

  10. Race characterization of BSR isolates from Huancayo, Peru. 2007

  11. Cali-sib x Bowman Shyri x Galena CI10587 x Galena BSR-45 D1-72 D3-6 Harrington Baronesse Orca BCD DB BCD47 BCD12 D3-6/B23 D3-6/B61 AJO BU OPS

  12. iBISON and BISON iBISON BISON

  13. ORO OWB Chr. 4H EBmac701 SSR markers used for MAS baal29j18 *

  14. Unmapped in OWB 2_0749 OWB Chr. 1H

  15. 2_0749 Unmapped in OWB

  16. OWB Chrom. 1H Shyri x Galena Act8 MWG837 2_0749* 2_0749* BCD098 2_0749* Inferred position

  17. OWB Chrom. 5H Cali sib x Bowman

  18. Flanking markers in each target region Three resistance genes in chromosome 1H, 4H and 5H

  19. THE PROBLEM • KURTFORD • 6 –rowed hooded feed barley • Well adapted to California conditions • Short height • Stripe Rust Susceptible

  20. iBISON 1H+4H+5H • Resistance alleles for the three genes • 2–rowed awned barley; short height

  21. SOLUTION: The Kurtford Conversion Year 1 I Bison 1H 4H 5H Kurtford 1H 4H 5H X SS SS SS RR RR RR Kurtford 1H 4H 5H F1 heterozygote at 3 BSR resistance loci X RS RS RS SS SS SS BC1F1 12.5% of plants expected to be heterozygote at 3 BSR resistance loci. Segregation in each locus: ½ RS ½ SS

  22. Summer – Fall 2007 • We have 589 BC1F1 seeds and we expect to find around 74 target heterozygotes at the 3 BSR resistance loci.We need: • -Confirm choice of markers • DNA extraction for 589 plants • Genotyping for the 3 BSR resistance regions • Selection of targeted genotypes MAS1 1H 4H 5H Bmag399 EST4473 EST4535 Baal29j18 . Bags 4e Bmag337 Bmag223 Bmag812

  23. I I I K I K I I K iBison 1H+4H+5H Kurtford

  24. Winter 2008 • Selection of heterozygotes (~74) • 10 seeds per selected plant ~ 740 BC1F2 plants. • Grow out and genotype BC1F2 plants segregating in each locus: ¼ RR ½ RS ¼ SS MAS2 We expect 25% of the BC1F2 to be homozygous for AT LEAST the 4H region (~ 185). Of these: ~ 104 homozygote only for 4H ~ 35 homozygote for 4H and 1H ~ 35 homozygote for 4H and 5H ~ 11 homozygote for 1H, 4H and 5H 25/64 (~ 38%) of the resistant plants will be homozygous hooded

  25. Winter 2008/2009 – seed increase Summer 2009 – validate resistance Field test ~ 70 homozygous hooded, BSR resistant plants

  26. Abundant, gene-based markers make MAS more effective and informative

  27. What makes a trait quantitative and not qualitative? Successful MAS may precede gene characterization Phenotypic performance is the ultimate measure of agronomic worth

  28. MAS - coming to a field near you

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