Uptake and translocation of mineral nutrients in plants is essential for plant growth and human nutrition. In spite of recent advances in identifying genes involved in nutrient transport, the systems that control acquisition of individual nutrients remain largely unknown. The major objective of the project is to identify gene networks that control uptake and accumulation of a wide array of plant nutrients and toxic metals. The approach makes use of recent technical advances in inductively-coupled plasma atomic emission spectroscopy (ICP-AES) which now permit the measurement of up to 72 different elements in 35 seconds per plant sample. Identifying genes controlling solute uptake and accumulation has significance for agriculture, human health and the environment. For example, enhancing the ability of a crop plant to mobilize soil nutrients should reduce the use of fertilizers, thereby making agriculture more cost efficient and less polluting. Because plants are the primary source of food for humans, either directly or through animal feed, the nutritional value of plants is of central importance to human health. The most widespread nutritional problem in the world is iron deficiency. Increasing the ability of plants to provide higher levels of minerals, such as iron, will have a dramatic impact on human health. Furthermore, understanding the pathways by which toxic metals accumulate in plants will enable the engineering of plants to exclude toxic metals and create healthier food sources, or to extract toxic metals from the soil as a strategy to clean up polluted lands and water.
The main aims of the project are to: 1) Use bioinformatics to identify genes that potentially encode transporters. 2) Use mRNA expression profiling to identify genes that change expression in response to nutrient deprivation or overfeeding. 3) Use nutrient profiling to screen for mutant plants with abnormal element compositions. ICP-AES will be used in a high-throughput strategy to determine the relative element composition of approximately 50,000 "tagged" mutagenized plants (Arabidopsis and either rice or maize if tagged lines are readily available in year 2). 4) Use yeast to obtain functional predictions of plant orthologs. The primary approach will be to conduct ICP-AES nutrient profiling of approximately 5,000 knockout lines of yeast. 5) Establish a Web site to provide access to data sets and enhanced annotation of genes. 6) Initiate collaborative research focused on selected mutations that control accumulation of Fe, Zn, K, Na, Ca, Se and Cd to further demonstrate the power of this novel approach. 7) Establish a program to train undergraduate and graduate students in genomics, informatics and plant molecular biological techniques. 8) Work with the Montshire Museum of Science to develop science curricula on metals in the environment.
This project will functionally identify many important genes, including those that are involved in: 1) mobilizing nutrients in the rhizosphere, 2) cellular uptake and efflux systems, 3) subcellular compartmentalization of solutes, 4) the operation of phloem and xylem translocation systems, 5) central regulation mechanisms, 6) sensing nutrient levels, and 7) controlling root structure. This functional genomic investigation will provide the first integrated picture of the genes involved in a fundamental feature of all living systems - the selective accumulation of essential minerals.
Participants: Mary Lou Guerinot, PI, Dartmouth College David Eide, Co-PI, University of Missouri Michael Gribskov, Co-PI, University of California at San Diego Jeffrey F. Harper, Co-PI, The Scripps Research Institute David E. Salt, Co-PI, Northern Arizona University Julian I. Schroeder, Co-PI, University of California at San Diego
