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SUMMARY:The Perennial Plant Clock: Implications for Growth and Winter Surv
 ival - Maria Eriksson\, Department of Plant physiology - Umea University
DTSTART:20101105T130000Z
DTEND:20101105T133000Z
UID:TALK26672@talks.cam.ac.uk
CONTACT:15560
DESCRIPTION:Components of the circadian clock as deduced from studies in A
 rabidopsis thaliana have counterparts in the sequenced genome of the decid
 uous tree species Populus trichocarpa. Functional studies have however bee
 n lacking. Recently we carried out a study on the role of the putative hom
 ologues of Arabidopsis LATE ELONGATED HYPOCOTYLS (LHY) and TIMING OF CAB E
 XPRESSION1 (TOC1) in Populus using trees with reduced expression of these 
 genes (Ibáñez et al.\, (2010) Plant Physiol 153:1823-1833).\nWe found th
 at the Populus homologues indeed function in the circadian clock mechanism
 \, and investigated further their role in the seasonal regulation of induc
 tion and exit of winter dormancy. Both LHY and TOC1 were shown to help def
 ine the critical day length\, that decide if trees are able to grow or not
 . Also\, unexpectedly\, LHY expression was needed in order to resume growt
 h in response to favorable temperature under Spring-like conditions.\nMore
 over\, during dormancy when perennials must be able to endure freezing tem
 peratures\, we found that trees need LHY expression to tolerate freezing. 
 In accordance with this finding the cold response was also compromised in 
 these trees since they were unable to up-regulate C-REPEAT BINDING FACTOR1
  (CBF1) in response to low temperature.\nThus\, we have shown that the cen
 tral circadian clock and its components needs to be functional to accurate
 ly time growth and for building of freezing tolerance\, both traits necess
 ary for survival and a perennial life style at higher latitudes.
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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