[Seminars] PSB event reminder

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Calendar Name: seminars
Scheduled for: Thursday, April 18 2013, 11:00 - 12:30
Event text:    Prof Dirk Inzé
	       Scientific Director
	       Head of Department
	       
	       VIB, Dept. of Plant Systems Biology
	       Ghent University
	       
	       Gent
	       BELGIUM
Details:       “LEAF growth: from images to molecular networks”
	       
	       ABSTRACT
	       Growth of plants and plant organs is orchestrated by
	       complex molecular networks that integrates both
	       intrinsic development signals encoded by the genome as
	       well as a wide variety of environmental cues such as
	       light, availability of water and minerals, temperature,
	       e.a. Understanding the molecular composition and
	       topology of these networks ultimately will accelerate
	       advanced breeding and gene engineering for higher
	       yielding crops. We have chosen leaves as a model organ
	       to understand growth and size control mechanisms. As
	       leaf growth is a quantitative trait, several (semi-)
	       automated growth analysis platforms were developed to
	       analyze leaf growth over time. Detailed cellular and
	       molecular analysis of numerous Arabidopsis mutants
	       revealed the existence of at least five mechanisms that
	       contribute to final leaf size: i) the initial size of
	       the leaf primordium; ii) cell cycle duration; iii) the
	       developmental timing of the transition from cell
	       division to cell expansion; iv) the timing of
	       meristemoid division; and v) cell expansion. For each
	       mechanism, multiple genes have been identified that when
	       overexpressed or mutated enhance leaf organ size. For
	       example, cell cycle duration appears to be controlled by
	       the ANAPHASE PROMOTING COMPLEX, a multi-protein E3
	       ligase that is involved in mitosis. On the other hand
	       the transition from cell division to cell expansion
	       during leaf development is mediated by the gibberellic
	       acid (GA) dependent activity of a chromatin remodeling
	       complex. GA levels in the growth zones are regulated by
	       the activity of two stress responsive transcription
	       factors ERF5 and ERF6 and our experimental data show
	       that these transcription factor have a pivotal role in
	       regulation growth in response to the environment.
	       Furthermore, GA also was shown to have an important
	       function in mediating leaf growth in maize and by
	       engineering GA metabolism maize leaves that have a 40%
	       increase in length were obtained. We will discussed our
	       current understanding of growth regulatory networks and
	       how we can use this information to improve crop yield.

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