Grand Challenges in Plant Nutrition

As a scientific discipline, plant nutrition stands on two legs. One leg is anchored in plant physiology and explains the fundamental processes underlying and regulating the acquisition, allocation, and utilization of mineral elements in plants. The other leg is deeply rooted in an applied, problem oriented context, explaining the use and action of fertilizers and the cycling of mineral elements in agricultural plant production. This creates completely different expectations on what plant nutrition shall accomplish. On the one hand, biochemical basics underlying nutritional processes shall be described down to the molecular level, such as the differential selectivity of membrane transporters for nutrients or signal-ing functions of mineral nutrients in plant development. On the other hand, large parts of the society, from farmers to policy makers , expect plant nutritionists to develop concepts that allow further enhancements in crop yield and quality while increasing nutrient efficiency and reducing nutrient losses from crop production systems. These different expectations generate a quite heterogenic community of plant nutritionists spanning from pure molecular biologists that never go beyond the gene or protein level to agronomists, who move between the whole-plant and field scales. Even though molecular and agronomic oriented plant nutritionists are aware of their mutual dependency, they tend to separate into different scientific subgroups using different publication organs. As one of the consequences, definitions and scientific standards set by these sub-communities of plant nutritionists tend to develop into different directions, becoming apparent for example in the choice and justification of plant growth conditions or the application of statistical methods to setup experiments and evaluate data. Thus, the plant nutrition community certainly faces one grand challenge in bridging the gap between basic and applied science and building an integrated community that tackles the open questions in a common effort. Recent progresses in physical and analytical chemistry, molecular biology and genetics have opened a large array of opportunities for plant nutritionists to address questions going beyond the fundamental processes of the uptake and utilization of mineral elements. Based on the most common workhorse in elemental analysis, inductively coupled plasma-mass spec-trometry (ICP-MS), significant improvements have been made to increase the sensitivity and number of simultaneously determined elements, to decrease the sample size required for analysis and for gaining additional information on the determined elements. These technical improvements include laser ablation-coupled ICP-MS to determine the subcellular distribution of elements (Conn and Gilliham, 2010) or size exclusion/ion pairing chromatography …