Flooding Survival Strategies in Rice and Arabidopsis

To help stabilize crop production it is essential to adopt germplasm that is better able to endure weather extremes such as droughts and floods. One example of this is the introduction of rice varieties that survive transient partial to complete submergence in Asia. Submergence tolerant rice has been generated by marker-assisted introgression of an allele of the SUBMERGENCE1A (SUB1A) gene from a landrace into modern varieties. Our work has characterized the functional roles of SUB1A in submergence survival. This and other members of the APETELA2/Ethylene Responsive Factor (ERF) group VII transcription factor family have proven to be pivotal regulators of flooding and low oxygen responses in plants. In Arabidopsis thaliana, the regulation of the abundance of group VII ERF proteins provides a homeostatic sensing mechanism of oxygen availability. Certain group VII ERFs are marked for degradation by a branch of the N-end rule pathway of targeted proteolysis under oxygen-replete conditions and become stabilized under oxygen deficient conditions. These proteins regulate the expression of a gene network that enables energy-efficient anaerobic metabolism and low-oxygen stress survival. Interestingly, our initial experimentation indicates that SUB1A evades oxygen-regulated N-end rule destruction, playing its role in an effective flooding survival strategy prior to severe oxygen deprivation. Through the evaluation of the gene networks regulated by group VII ERFs in rice and Arabidopsis, we have further resolved the counterbalanced stratagems that enable survival of transient floods.

Funded by the National Science Foundation (MCB-1021969, IOS-1121626) and the USDA National Institute of Food and Agriculture (2011-04015).