ARS | Publication request: Temporal assessment of gene expression in source leaves of Medicago truncatula: Correlations with seed Fe concentration

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2012
Publication Date: June 17, 2012
Citation: Garcia, C.B., Grusak, M.A. 2012. Temporal assessment of gene expression in source leaves of Medicago truncatula: cCrrelations with seed Fe concentration [abstract]. Proceedings, XVI International Symposium on Iron Nutrition and Interactions in Plants, June 17-21, 2012, Amherst, Massachusetts. p. 63.

Technical Abstract: Mineral accumulation in seeds is dictated by several processes, including nutrient mobilization from source tissues. The timing and robustness of these processes, with respect to seed growth and development, may affect harvest characteristics such as seed number and seed weight as well as nutritional qualities like macro- and micronutrient concentrations. Previous studies have identified quantitative trait loci (QTLs) associated with variation in seed micronutrient concentrations in the model legume Medicago truncatula; however, the genes located within these loci, their temporal and spatial expression patterns, and their molecular functions have not been clearly determined. Several of these genes encode putative transcriptional regulators, membrane transporters, and proteins involved in intracellular signaling. We hypothesize that the timing and level of expression of these genes within source leaf tissue during seed development modulates final seed iron (Fe) concentration. Comparison of gene expression in leaves of an ecotype (Jemalong) with low seed Fe concentration, relative to an ecotype (DZA315.16) with a high seed Fe concentration, revealed differences in the temporal expression of some genes within these QTLs. Additionally, senescence-associated genes were expressed at an earlier timepoint following anthesis in DZA315.16 compared to Jemalong. These data suggest that differential gene expression in source tissue underlies variation in seed Fe concentration. Future studies will focus on determining the regulatory pathways that control this transcriptional program and the molecular function of the genes identified through the QTL analysis.