Hexaploid wheat The Ph 1 locus stabilises wheat
Hexaploid wheat- The Ph 1 locus stabilises wheat, Triticum aestivum 2 n= 6 x= 42 ensuring high fertility 1 2 3 4 5 6 7 a b c d A a b c d B a b c d 7 D 7 D a b c d Homoeologues a b c d 7 B 7 B 7 A 7 A D a b c d The Ph 1 locus (a dominant locus) restricts pairing to homologues Riley and Chapman (1958) Nature Very large chromosomes with similar gene orders
Importance of Ph 1 in Breeding Wild species of wheat carry important traits for disease resistance, salt, cold and drought tolerance Ph 1 stops wheat and wild species chromosomes pairing A single wheat carrying a deletion of Ph 1 locus (ph 1 b- 70 Mb in size) used in breeding- is heavily rearranged Wheat-rye hybrid Ph 1+ Ph 1 - Can we from understanding Ph 1 locus, temporary switch Ph 1 off in hybrids of elite wheat varieties crossed with wild species?
Ph 1 story Ph 1 locus is a Cdk 2 -like gene complex Cdk 2 in humans remodels chromatin for replication All chromosomes replicated together Ph 1+ Ph 1 Cdk 2 rate homologues Cdk 2 limiting Abundant remodelling A A slows B Homologues premature remodelling a a B b b Different expression patterns Ph 1+ Homoeologues remodelled together homoeologues Ph 1 - Homologues and homoeologues replicated at different times as remodelling is slowed- thus will be in different conformations for meiosis
Drug strategyneedle in haystack? • How do you activate cdk? • Inhibit phosphatases which deactivate cdksincrease cdk activity? Phosphatase inhibitors cause premature condensation and rapid progression through meiotic prophase I in humans and mouse
Application? Can we improve the exploitation the introgression process? Ph 1+ Wheat x rye hybrid • Can we inhibit phosphatases to modulate pairing in hybrids?
- Slides: 5