[Seminars] PSB event reminder

[contact at psb.vib-ugent.be]

Calendar Name: seminars
Scheduled for: Thursday, January 20 2011, 11:00 - 12:30
Event text:    Dr Wim Soppe
	       
	       Dept. of Plant Breeding and Genetics
	       Max Planck Institute for Plant Breeding Research
	       
	       Cologne
	       GERMANY
Details:       "Waking up in time, seed dormancy explained at the
	       molecular level"
	       
	       ABSTRACT
	       Viable plant seeds are not always able to germinate and
	       can cycle between a dormant and a non-dormant state.
	       Dormancy prevents germination during unfavourable
	       seasons, an ability that has been lost in most of our
	       crop species. In the model plant Arabidopsis, dormancy
	       is induced during the maturation of seeds in the silique
	       and released by imbibition of seeds at low temperatures
	       (stratification) or dry storage (after-ripening). Seed
	       dormancy is determined by the balance between the plant
	       hormones abscisic acid and gibberellins. However, our
	       knowledge about the molecular identity of dormancy and
	       its control by environmental factors is limited. To
	       reveal the molecular mechanisms that determine the
	       induction and release of seed dormancy, my research
	       group has analysed and cloned Arabidopsis mutants with
	       reduced dormancy levels. The underlying genes could be
	       divided in two groups.
		       The first group contains ubiquitously expressed
	       genes with a general role in plant development.
	       Transcription factors, associated with elongating RNA
	       polymerase II, are overrepresented in this group. Most
	       of these genes are upregulated towards the end of seed
	       maturation. Interestingly, this upregulation is
	       correlated with a strong reduction in nuclear size
	       during seed maturation. This suggests that RNA
	       polymerase associated factors are required to facilitate
	       gene expression in nuclei with reduced volume. An
	       example of a gene belonging to this group is HUB1, which
	       encodes a C3HC4 RING finger protein that is required for
	       monoubiquitination of histone H2B. We observed altered
	       expression levels for several dormancy genes in the hub1
	       mutant towards the end of seed maturation.
		       The second group consists of dormancy genes with
	       a seed-specific expression. The gene DELAY OF
	       GERMINATION 1 (DOG1), which is expressed during seed
	       maturation and encodes a protein with unknown function,
	       belongs to this group. DOG1 is essential for seed
	       dormancy because the dog1 mutant is completely
	       non-dormant. DOG1 expression is upregulated by reduced
	       temperatures during seed maturation. Higher levels of
	       DOG1 protein in ripe seeds require an increasing
	       after-ripening time to release seed dormancy. DOG1 is
	       alternatively spliced and we have shown that DOG1
	       function requires binding between its different protein
	       isoforms.
		       In this seminar, I will present our present
	       understanding of the molecular mechanism of seed
	       dormancy in Arabidopsis and focus on the roles of RNA
	       polymerase II associated factors and DOG1.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://maillist.psb.ugent.be/mailman/private/seminars/attachments/20110120/78d5bbc7/attachment.html