Mitteilungen der Gesellschaft für Pflanzenbauwissenschaften Band 23

Mitt. Ges. Pflanzenbauwiss. 23: 153 (2011)
Exploring the role of poly(ADP-ribose)polymerases in plants
Dagmar Rissel 1,2 , Kathrin Thor 2 and Edgar Peiter 2
1 Agrochemisches Institut Piesteritz e. V., Lutherstadt Wittenberg; 2 Plant Nutrition Laboratory, IAEW,
Universität Halle-Wittenberg. E-Mail: dagmar.rissel@landw.uni-halle.de
Introduction
Poly(ADP-ribosyl)ation is a fast transient posttranslational protein modification.
Activated upon DNA strand breaks, poly(ADP-ribose) polymerases (PARPs) add
ADP-ribose molecules to nuclear proteins involved in DNA strand break repair
mechanisms. Thereby NAD + is used as a substrate to build up ADP-ribose polymers.
In the model plant Arabidopsis thaliana three PARP genes (AtPARP1, AtPARP2 and
AtPARP3) have been identified. Recent studies suggest a role of poly(ADPribosyl)ation
in the plant response to abiotic stress (De Block et al. 2005;
Vanderauwera et al. 2007): Plants with reduced expression of AtPARP1 and
AtPARP2 were shown to have an increased tolerance towards drought stress and
oxidative stress induced by reactive oxygen species (ROS) [1]. However, the
mechanisms of how PARPs are involved in plant stress responses are still a matter
of debate.
Material and Methods
To elucidate the role of PARPs in plant stress response Arabidopsis parp knockout
mutants were cultured on agar plates containing mannitol (drought stress), NaCl or
methyl viologen (oxidative stress). During culture the root length of mutant and wild
type plants was measured. After culture root and shoot fresh weight of the plants was
determined. The parp single mutants were crossed with each other to create double
knockout mutants. Homozygous F2 plants are currently being analysed for their
stress tolerance. Apart form that seed germination of parp mutants was scored on
agar plates.
Results and Discussion
Arabidopsis PARPs have been suggested to be involved in plant stress response.
Surprisingly, in our hands parp single mutants did not display any enhanced stress
tolerance so far. Since PARP genes may be functionally redundant, parp single
mutant lines were crossed to create double mutants. The abiotic stress tolerance of
these plants is currently under investigation. Interestingly, parp single mutants
showed a delay in germination under standard growth conditions. After artificial seed
aging the delay in germination was even more pronounced in the parp mutants
indicating that this phenotype was not due to an increased seed dormancy. The
mechanism underlying this phenomenon is under investigation.
References
De Block M., Verduyn C., De Brouwer D., Cornelissen M. 2005: Poly(ADP-ribose) polymerase in
plants affects energy homeostasis, cell death and stress tolerance. Plant J. 41:95-106.
Vanderauwera S., De Block M., Van de Steene N., Van de Cotte B., Metzlaff M., Van Breusegem F.
2007: Silencing of poly(ADP-ribose) polymerase in plants alters abiotic stress signal transduction.
PNAS 104:15150-15155.