Phosphate: the Silent Challenge

Phosphorus (P) is one of the most vital elements for all living organisms which acts as aconstituent of essential biomolecules such as nucleic acids, phospholipids, and phosphosugars,and as a major contributor to almost all metabolic reactions including photosynthesis,respiration, and energy delivery. It is one of the most needed nutrients for plant growth anddevelopment. Despite high levels of P in the soil, plants absorb it only in the soluble inorganicform of free phosphate ion (Pi) which is scarce in soil. Therefore, there has been a large demandfor Pi fertilizers to secure crop yields, yet its deposition in soil and gradual run-off into waterreservoirs lead to chains of events that cause irreversible damages to ecosystems. Researches,including genome-wide data analyses, have revealed interesting molecular aspects of plantadaptive strategies to deal with low Pi concentrations in soil. These include the higherexpression of acid phosphatases and Pi transporters as well as the secretion of organic acids inthe rhizosphere that maintain cellular Pi homeostasis in order to keep metabolic reactionsrunning. Describing the cycle of Pi exchange between physical and biological worlds, the extentto which current agricultural practices are disturbing the cycle, the necessity of introducing lessdestructivemethods of providing Pi, and alternative measures and solutions for sustainableagriculture will be discussed in this review.