SXRF IMAGING OF LIVE ARABIDOPSIS PLANTS TO CHARACTERIZE GENES INVOLVED IN METAL

Stanford University, Stanford CA

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Abstract

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We would like to collect SXRF elemental images from living samples of Arabidopsis thaliana, specifically from wild type and transgenic (genetically modified) mutant plants, to characterize genes involved in metal/metalloid ion homeostasis. Our work involves the micronutrient Fe and the contaminant As. Iron is limiting in the soil, and plants contain low levels of Fe;increasing Fe deficiency anemia in those with predominantly plant-based diets. Engineering plants that take up and store greater amounts of Fe in their edible tissues (i.e. seed) (biofortification) is thought to be a viable solution. As well as being naturally low in Fe, the widely-consumed staple rice has been found to be contaminated with As. Rice plants take up large amounts of silicon (Si), in the form of silicic acid;similar in size and charge to arsenous acid, a prevalent form of As in flooded paddy soils, remaining in the soil from previous arsenical pesticide use. Translocation of As in to the plant, and in to the edible portion of the grain (endosperm) is under the control of genes, and manipulation of these genes can reduce As accumulation in the rice endosperm. We utilize genetic and genomic technique to develop transgenic plants that either lack a gene or genes of interest (knock-out mutants), or express the gene of interest in every cell (overexpressor mutants). On a tissue or cell level, we require non-destructive spatially resolved micron-scale metal/metalloid analysis to understand how deletion or over-expression of genes affects metal/metalloid ion transport in to different cell layers, and to different organelles within the cell. Rapid access is needed to allow immediate publication of the influence of the gene VIT1 (vacuolar iron transporter 1) on the distribution of Fe.