ARS | Publication request: USING NATURAL VARIATION FOR GENE DISCOVERY TO IMPROVE SEED IRON NUTRITIONAL VALUE

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 7, 2006
Publication Date: July 7, 2006
Citation: Waters, B.M., Grusak, M.A. 2006. Using natural variation for gene discovery to improve seed iron nutritional value. In: Proceedings of the Thirteenth International Symposium on Iron Nutrition and Interactions in Plants, July 3-7, 2006, Montpellier, France. p. 128.

Technical Abstract: We and others are interested in developing crops biofortified with iron to improve their nutritional value for human consumption. One of the crucial tasks, therefore, is to identify relevant genes that can be targeted for transgenic or conventional breeding approaches to improve the Fe concentration of harvested crops. We are using the model plant Arabidopsis thaliana to identify genes that increase seed Fe and other mineral concentrations. The abundance of genomic and genetic information available for Arabidopsis makes this plant an ideal model. Our initial approach was to screen recombinant inbred line (RIL) populations for quantitative trait loci (QTL). Individual lines of two populations, Col X Ler and Cvi X Ler, were grown in potting mix subirrigated with complete nutrient solution. At maturity, seeds were collected and seed mineral concentrations were determined by ICP-OES. Mineral concentrations in both RIL populations exhibited transgressive segregation, with seed Fe concentration ranging from 55-118 ppm in the Col X Ler population, and from 57-158 ppm in the Cvi X Ler population, suggesting that there is genetic capacity for seed iron concentration improvement. Seed Fe concentration was positively correlated with seed Zn concentration in both populations. In the Cvi X Ler population, a QTL that explained 30% of variation in seed Fe concentration was identified on chromosome 2, and a QTL that explained 21% of seed Fe variation was identified on chromosome 3. QTL were also identified for Ca, Cu, K, Mg, Mn, P, and Zn. From mapped QTL, candidate genes were selected from those with known or inferred functions related to iron uptake or homeostasis. Candidate genes will be evaluated by sequencing to identify possible polymorphisms in the open reading frame or promoter regions. If available, effects of knockouts of candidate genes will be presented. Another approach we are pursuing is to characterize seed mineral concentrations in wild-collected ecotypes of Arabidopsis. These results will be used in combination with potential allelic variation in metal genes, as another method for gene discovery. This work was supported in part by funds from USDA-ARS under Agreement No. 58-6250-6-001 and from the Harvest Plus Project under Agreement No. 58-6250-4-F029 to MAG.