Tom Beeckman
Root Development
VIB Department of Plant Systems Biology, UGent

PhD: Univ. of Ghent, Ghent, Belgium, '97 Principal Investigator VIB since 2001

e-mail phone +32 9 331 39 30 ADDRESS

Current team members
Group leader: Tom Beeckman
Postdoctoral scientists: Boris Parizot, Dominique Audenaert, Giel Van Noorden
Ph.D. Students: Inge Verstraeten, Leentje Jansen, Lorena Lopez, Marlies Demeulenaere, Wei Xuan
Support personnel: Gert Van Isterdael, Le Son Long Nguyen, Maria Njo, Toke Thiron

Keywords
root development - phytohormones - cell cycle - functional genomics - plant transgenesis and phenotyping

Science

Plant roots serve a multitude of functions. They anchor and supply plants with water and nutrients and exchange various growth substances with the shoots. During the last ten years, Arabidopsis thaliana has been proven to be an efficient model plant to study root development. Besides the various advantages this plant offers in genetic and molecular studies, the Arabidopsis root boasts quite predictable ontogeny, very simple anatomy and a high level of transparency, making it very suitable for morphogenetic and cell-biology studies. Understanding how root systems develop is crucial for maximising crop production in a world in which population is increasing and the amount of arable land is decreasing. Lateral-root formation or root branching is one of the major regulators of root-system architecture. During root branching, developmental and environmental controls of cell-cycle regulation are crucial. Mitotic activity must be renewed in differentiated pericycle cells that have left the cell cycle. In Arabidopsis, the lateral roots are initiated by local activation of the pericycle cells at the xylem poles (Casimiro et al., 2003). Unique cell-cycle control, dissimilar from that in other pericycle cells, was shown to take place in the xylem pericycle (Beeckman et al., 2001). Good knowledge of this tissue-specific cell-cycle regulation is therefore needed for better understanding of lateral root initiation.
  
To efficiently study the molecular and cytological events during the early stages of pericycle activation, a lateral root-inducible system was developed. Successive treatments with an auxin transport inhibitor and exogenous auxin were used to prevent the first formative divisions and to activate the whole pericycle, respectively. In this system, cell-cycle progression during the early course of lateral root induction was monitored using histochemical and molecular techniques.  The results demonstrated that the CDK inhibitory proteins (KRPs) play a previously unknown role in specifically preventing lateral root initiation at the G1-tot-S transition (Himanen et al., 2002). The signalling cascade towards the specification of the lateral root founder cells and the asymmetric divisions is up to now not elucidated and represents the major theme of our current research. Three independent but complementary transcript profiling studies have been performed using the lateral root inducible system (Himanen et al., 2004, Vanneste et al., 2005; De Smet et al., in prep.). Based on the global changes in the transcriptome during the initial phase of lateral root induction functional analyses of potential key-regulators for root branching are currently being analysed.

Press releases
See also press release (07/11/2008): Annuals converted into perennials - based on a publication in Nature Genetics (Siegbert Melzer et al., 2008).

See also press release (27/10/2008): Scientists unveil mechanism for ‘up and down’ in plants - based on a publicaton in Science (De Smet et al., 2008).

See also press release (24/10/2008): Origin of root offshoots revealed - possible basis for new ecological agricultural applications - based on a publication in Science (De Smet et al., 2008)

De Smet I, Lau S, Voss U, Vanneste S, Benjamins R, Rademacher E, Schlereth A, De Rybel B, Vassileva V, Grunewald W, Naudts M, Levesque M, Ehrismann J, Inzé D, Luschnig C, Benfey P, Weijers D, Van Montagu M, Bennett M, Jürgens G, Beeckman T
Bimodular auxin response controls organogenesis in Arabidopsis
P NATL ACAD SCI USA 107, 2705-2710, 2010



De Smet I, Voss U, Jurgens G, Beeckman T
Receptor-like kinases shape the plant
NAT CELL BIOL 11, 1166-73, 2009



Swarup K, Benková E, Swarup R, Casimiro I, Péret B, Yang Y, Parry G, Nielsen e, De Smet I, Vanneste S, Levesque M, Carrier D, James N, Calvo V, Ljung K, Kramer E, Roberts R, Graham N, Marillonnet S, Patel K, Jones J, Taylor C, Schachtman D, May S, Sandberg G, Benfey P, Friml J, Kerr I, Beeckman T, Laplaze L, Bennett M
The auxin influx carrier LAX3 promotes lateral root emergence
NAT CELL BIOL 10, 946-54, 2008



De Smet I, Vassileva V, De Rybel B, Levesque M, Grunewald W, Van Damme D, Van Noorden G, Naudts M, Van Isterdael G, De Clercq R, Wang J, Meuli N, Vanneste S, Friml J, Hilson P, Jurgens G, Ingram G, Inzé D, Benfey P, Beeckman T
Receptor-like kinase ACR4 restricts formative cell divisions in the Arabidopsis root
SCIENCE 322, 594-7, 2008



De Smet I, Tetsumura T, De Rybel B, Frey N, Laplaze L, Casimiro I, Swarup R, Naudts M, Vanneste S, Audenaert D, Inzé D, Bennett M, Beeckman T
Auxin-dependent regulation of lateral root positioning in the basal meristem of Arabidopsis
DEVELOPMENT 134, 681-90, 2007

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