Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/2008
Publication Date: 10/11/2008
Citation: Urbanski, D., Sandal, N., Orlowska, E., Stougaard, J., Jensen, E.O., Przybylowicz, W.J., Mesjasz-Przybylowicz, J., Klein, M.A., Grusak, M.A., Husted, S., Cvitanich, C. 2008. Differential iron distribution in seeds of two closely related legume species [abstract]. XIV International Symposium on Iron Nutrition and Interactions in Plants, October 11-16, 2008, Beijing, China. p. 50.
Technical Abstract: The World Health Organization states that the lack of micronutrients such as zinc and iron represents a major threat to the health and development of populations around the world. Iron deficiency affects over 2 billion people, in particular children and pregnant women in developing countries. A common nutritional base for poor populations is a staple such as maize, wheat, rice, potatoes, cassava, or beans, many of them having low iron content as well as potent inhibitors for iron uptake. Nutritional supplements are often unavailable to such populations due to poor infrastructure, education, and funding. We are studying legumes that can be grown in poor soils and for many people are affordable and sustainable substitutes for meat in the diet. Legumes such as soybeans, common beans, and lentils are rich in iron and protein. In contrast to meat, however, plant iron is less bioavailable. In beans there is a large natural variation for iron concentration between different cultivars and landraces. It is therefore realistic through conventional crossings to introduce the high iron trait into elite cultivars. Measuring iron in each progeny line is time-consuming and expensive, so molecular markers following the high iron traits are desirable. As part of the HarvestPlus objective to generate new cultivars of staple crops with increased micronutrients, the goal of our project is to contribute to the breeding of common bean varieties with high iron concentration. We will characterize genes responsible for the accumulation of iron in legume seeds and develop molecular markers that will follow the high iron trait. We are using the model legume Lotus japonicus and the closely related species Lotus filicaulis. These two Lotus species accumulate significantly different amounts of iron in their leaves and seeds. In addition it is possible to cross them, and recombinant inbred lines are available. In this project we are characterizing these two Lotus species in order to elucidate the physiological mechanisms behind the differential accumulation of iron in the aerial parts of the plants. We are studying the plants' ability to reduce the pH of the growth media, the iron-reducing activity of their roots, and the distribution of iron in their seeds. Little is known about the distribution of iron in mature legume seeds. This knowledge is important to our search for genes that contribute to iron loading in these seeds. Therefore we have characterized the distribution of iron in untreated mature seeds of L. japonicus and L. filicaulis by simultaneously using Micro-PIXE and proton backscattering. Elemental maps were obtained by the Dynamic Analysis method and the information from these maps was complemented by calculating average concentrations of elements from selected areas within seeds. In addition, biochemical staining of iron in mature and germinated seeds was performed, and this material was studied by light microscopy before and after tissue fixation and sectioning.