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Suppression of Ph1 in Aegilops speltoides: Practical Utility for Wheat Chromosome 5B

This study explores the role of Aegilops speltoides in suppressing Ph1 and promoting homoeologous pairing in wheat, providing practical utility for improving wheat breeding programs. The suppression of Ph1 is controlled by multiple genes and can increase the number of chiasmata per cell, leading to improved recombination.

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Suppression of Ph1 in Aegilops speltoides: Practical Utility for Wheat Chromosome 5B

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  1. Aegilops speltoidesPh1 suppressors Practical utility for wheat

  2. Chromosome 5B is responsible for diploid-like meiotic chromosome pairing in hexaploid T. aestivum Euploid Nullisomic 5B R. Riley, Heredity 15:407-429, 1960

  3. Triticum urartu (AA genomes) Wild emmer wheat (AABB genomes ) Aegilops speltoides SS genomes (extant relative of the B genome)

  4. Aegilops speltoides Surprisingly, Ae. speltoides was found to not have Ph1 but to promote homoeologous pairing in wheat.

  5. T. aestivum x Ae. speltoides Ph1 suppression is controlled by two unlinked duplicated major genes and several minor genes K.C. Chen and J. Dvorak, Can. J. Genet. Cytol. 26:279-287, 1983

  6. Mean numbers of chiasmata per cell in hybrids involving low- and high-pairing Ae. speltoides inbred lines low-pairing high pairing Ae. speltoides x Ae. tauschii Ae. speltoides x Ae. caudata No. chismata

  7. The average chiasma number per cell in hybrids T. aestivum backcrosses x Ae. variabilis Chen et al. TAG 88:97-101, 1994 16 14 12 10 Mean chiasma number 8 6 4 2 0 lowint. PhI

  8. Comparison of Ae. speltoides chromosome 1S and T. monococcum chromosome 1Am genetic maps

  9. Comparison of Ae. speltoides chromosome 3S and T. monococcum chromosome 3Am genetic maps

  10. 590 hybrids were produced, no. chiasmata per cell was estimated, DNA were isolated, and Southern blots were hybridized with informative markers • The population of 590 hybrids was partitioned by marker allele • ANOVAs were computed to determine marker effect on pairing

  11. Increase in the mean number of chiasmata per cell over background (= 7 chiasmata per cell) 10 9 8 7 6 5 Mean no. chiasmata per cell 4 3 2 1 0 5S

  12. Increase in the mean number of chiasmata per cell over background (= 7 chiasmata per cell) 10 9 8 7 6 5 Mean no. chiasmata per cell 4 3 2 1 0 5S 7S 3S 3S+7S 3S+7S+5S

  13. Increase in the mean number of chiasmata per cell over background (= 7 chiasmata per cell) 10 9 8 7 6 5 Mean no. chiasmata per cell 4 3 2 1 0 5S 7S 3S 3S+7S 3S+7S+5S

  14. Increase in the mean number of chiasmata per cell over background (= 7 chiasmata per cell) 10 9 8 7 6 5 Mean no. chiasmata per cell 4 3 2 1 0 5S 7S 3S 3S+7S 3S+7S+5S

  15. Increase in the mean number of chiasmata per cell over background (= 7 chiasmata per cell) 10 9 8 7 6 5 Mean no. chiasmata per cell 4 3 2 1 0 5S 7S 3S 3S+7S 3S+7S+5S

  16. Segregation of Su1-Ph1 in T. aestivum x Ae. speltoides hybrids

  17. Effect of segregation for Su1-Ph1 on meiotic pairing in T. aestivum x Ae. speltoides hybrids - +

  18. Genetic maps of the Su1-Ph1 region in Ae. speltoides

  19. PCR assay for marker PSR1205 using Ae. speltoides genome specific primers Chinese Spring BC4 wheat segregant without Ph1-Su1 Ae. speltoides BC4 wheat segregant with Ph1-Su1

  20. The average chiasma number per cell in hybrids T. aestivum backcrosses x Ae. variabilis Chen et al. TAG 88:97-101, 1994 16 14 12 10 Mean chiasma number 8 6 4 2 0 lowint. PhI

  21. The average chiasma number per cell in hybrids T. aestivum backrosses x Ae. variabilis Chen et al. TAG 88:97-101 Su1-Ph1 data Mean chiasma number Su1-Ph1 - lowint PhI Su1-Ph1 +

  22. The use of Ph1-Su1 in alien gene transfer in wheat Alien DS line x Ph1-Su1 line F1 targeted recombination between the alien chromosome and wheat homoeologue BC1 select recombinants without Ph1-Su1 using molecular markes

  23. Acknowledgements Kuey-Chu Chen Ming-Cheng Luo Karin R. Deal

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