University of Maryland Cracks 60-Year Code Through Discovery of Enzyme that Optimizes Plant Life

UMD scientists use plant model Arabidopsis to facilitate auxin inactivity

September 20, 2016

A recent PhD graduate and assistant professor from the University of Maryland’s College of Agriculture and Natural Resources have solved a riddle that scientists have been pondering for 50-60 years. Through a combination of biochemistry, genetics, molecular biology, physiology and metabolomics, a team in Plant Sciences and Landscape Architecture and Environmental Science and Technology led by Dr. Jun Zhang and Dr. Wendy Peer have discovered the primary way auxin is inactivated, or “turned off,” through identification and characterization of an enzyme called dioxygenase of auxin oxidation (DAO). Moving forward, plant life can be optimized through a proper balance of active auxin.

Auxin is the determining factor in how a plant grows, develops and responds to the environment. Controlling when and where and how much auxin is active via DAO can lead to crop improvement. This could have wide-ranging effects in crops from improving drought stress to increasing biomass. Benefits for the nursery industry include improved rooting of cuttings from tomatoes to trees.

Zhang and Peer use the plant model Arabidopsis to showcase the inactivation of auxin by way of DAO, facilitating a process called oxidation which turns auxin off. Despite the widespread recognition of auxin oxidation, prior to these findings, the enzymes that catalyze this process and how they work and influence plant growth were hinted at in apple and rice.

“We are excited about solving this puzzle at last,” says Dr. Wendy Peer. “Our goal is to address the world food crisis in the face of climate change. Understanding and then controlling the activity of this essential plant hormone is one of the keys to doing just that.”

A paper detailing the particular science behind the DAO function was published today in Proceedings of the National Academy of Sciences (PNAS) under the title “DAO1 catalyzes temporal and tissue-specific oxidative inactivation of auxin in Arabidopsis thaliana.” This is one of three papers published together on this subject. UMD is demonstrating the biochemistry, physiology, and metabolomics of DAO in tandem with The Ohio State University, with Umeå Plant Science Centre, Sweden, and the University of Nottingham, UK authoring on auxin metabolomics and physiology and DAO functions in auxin homeostasis in roots, respectively.