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Title: Genetic variability of oxalate oxidase activity and elongation in water-stressed primary roots of diverse maize and rice lines

Author
item VOOTHULURU, PRIYAMVADA - University Of Missouri
item THOMPSON, HALLIE - University Of Missouri
item Flint-Garcia, Sherry
item SHARP, ROBERT - University Of Missouri

Submitted to: Plant Signaling and Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/31/2012
Publication Date: 3/1/2013
Citation: Voothuluru, P., Thompson, H.J., Flint Garcia, S.A., Sharp, R.E. 2013. Genetic variability of oxalate oxidase activity and elongation in water-stressed primary roots of diverse maize and rice lines. Plant Signaling and Behavior. 8:e23454. Available: http://www.landesbioscience.com/journals/psb/article/23454/.

Interpretive Summary: Corn (maize) and rice are both important cereal crops worldwide. Drought can severely limit production of both crops, and efforts are underway to identify mechanisms of drought tolerance. One such mechanism is the maintenance of root growth under drought conditions. Previous studies indicate that several biochemical pathways could be involved in maintaining root growth under drought conditions, including the production of reactive oxygen species by oxalate oxidases, similar to free radicals. We surveyed a diverse sample of maize and rice varieties from around the world and measured their root growth and oxalate oxidase activity under drought conditions. We found that none of the rice varieties showed oxalate oxidase activity, while maize varieties showed highly variable patterns of oxalate oxidase activity. Both crops showed variability in root growth under drought. Root growth and oxalate oxidase activity patterns do not appear to be related, indicating that multiple mechanisms may be responsible for maize root growth. The findings of our study will be useful to physiologists and geneticists in their efforts to understand drought tolerance mechanisms, ultimately leading to the development of drought tolerant crop varieties.

Technical Abstract: Previous work on maize primary roots under water stress showed that cell elongation is maintained in the apical region of the growth zone but progressively inhibited further from the apex. In association with these responses, several proteins related to reactive oxygen species (ROS) production, particularly oxalate oxidases (OXOs), are increased in abundance predominantly in the apical region of the growth zone of water-stressed roots. In this study, we characterized root elongation and OXO activity responses of diverse maize and rice lines to water deficit conditions. The results revealed that although there is genetic variability in the root elongation to water stress, it is not correlated with increased OXO activity in the apical region. The implications of these findings in root growth regulation under water stress conditions are discussed.