Does anoxia tolerance involve altering the energy currency towards PPi?

Oxygen deficit is an important abiotic stress influencing plants, because this condition results in an ‘energy crisis’. Most species only survive short periods of anoxia, but several wetland species tolerate prolonged anoxia. Transcriptomic and proteomic studies, using anoxia-tolerant rice and anoxia-intolerant Arabidopsis, have provided evidence for the selective adoption of pyrophosphate (PPi) over ATP as high-energy donor molecules, which may contribute to anoxia tolerance. The use of PPi in some tolerant plant species is similar to that observed in many anaerobic prokaryotes. Investigations are being performed to better understand the origin and regulation of reversible PPi-dependent glycolytic enzymes such as cytosolic pyruvate phosphate dikinase, as well as PPi-consuming enzymes, which are engaged during the anoxic energy crisis. This will be crucial in unraveling this currency switch and its contribution to anoxia tolerance.