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SUMMARY:Unravelling the 50 year old Ph1 puzzle in wheat - Graham Moore\, J
 ohn Innes Centre
DTSTART:20100225T160000Z
DTEND:20100225T170000Z
UID:TALK22268@talks.cam.ac.uk
CONTACT:Ian Henderson
DESCRIPTION:The foundation of western civilisation owes much to the high f
 ertility of hexaploid (bread) wheat\, which results from the stabilisation
  of its polyploid genome. Despite possessing multiple sets of diploid chro
 mosomes\, hexaploid wheat behaves as a diploid at meiosis\, with the Ph1 l
 ocus promoting the correct pairing of homologous chromosomes. In hybrids o
 f wheat with wild relatives\, Ph1 prevents pairing and recombination betwe
 en the different chromosomes. This failure in chromosome exchange prevents
  breeders from exploiting the diversity of wild relatives within their pro
 grammes.\n\nThe cell biology studies reveal that Ph1 is a master regulator
  of wheat premeiosis and meiosis\, through its ability to control chromati
 n structure\, replication\, meiotic gene expression\, chromosome pairing a
 nd recombination.\n\nMapping Ph1 has been complicated by the absence of al
 lelic variation\, being only possible to score for its presence or absence
 \, thereby excluding conventional mapping approaches. The strategy to iden
 tify Ph1 involved the deployment of the rice synteny concept\, the physica
 l contiging of 7Mb of the wheat genome\, generation of 8 mutagenised popul
 ations and the individual screening of some 50\,000 mutant lines. This rep
 resented more than 30 man-years of work. \n\nThis study defined Ph1 to reg
 ion containing a gene complex disrupted by a piece of sub-telomeric hetero
 chromatin. The Ph1 gene has homology to a mammalian gene at the core of re
 gulating replication through controlling chromatin structure. This year\, 
 researchers have shown that this mammalian gene has\, as they describe\, a
 n “unpredicted” role in meiosis. It also controls chromosome pairing a
 nd recombination\, thereby suggesting that it too has a major regulatory r
 ole in controlling key events during premeiosis and meiosis. The fundament
 al mechanisms of recognizing homologous chromosomes in meiosis are therefo
 re likely to be conserved in mammals and plants. Thus pre-existing mechani
 sms have been modified in plants to deal with the additional problems enco
 untered due to genome size and polyploidy. We have now exploited this info
 rmation using a drug which regulates the mammalian gene\, to also regulate
  Ph1 which will be of practical benefit to breeding programmes.\n
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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