Poster: Nutrient Biology

Abs # 393: Characterization of Genes Related to Plant Mineral Nutrition in Arabidopsis

Presenter:	Wang, Yi-Hong , yw58@cornell.edu
Authors	Wang, Yi-Hong  (A)   Pence, Nicole S (A)   Kochian, Leon V (A)
Affiliations:	(A): Cornell University

Macro- and micronutrients play vital roles in plant growth and development. We have identified transcription factors (TGA1 and E2F1) functionally related to macronutrient and micronutrient (Zn) nutrition. TGA1 is involved in stress responses and is developmentally regulated while E2F1 is a cell cycle regulator. We previously showed that the tomato transcription factor LeTGA1 (Nitf) is induced by nitrogen (N) resupply, and phosphorus (P), potassium (K) and iron (Fe) starvation and was predominantly expressed in the root. Overexpression of LeTGA1 in Arabidopsis did not produce a distinct phenotype. Therefore, gene expression profiling was used to survey the expression of other genes that might be altered by LeTGA1 overexpression. This approach showed that a number of N metabolic enzymes and different transporters were upregulated in the overexpression lines. The closest Arabidopsis homolog of this tomato gene, AtTGA1, was found to also be induced by N resupply and predominantly expressed in the root. A T-DNA knockout of AtTGA1 has been identified and is being characterized. With regards to Zn homeostasis, we have identified a transcription factor that may be involved in Zn-dependent regulation of gene expression. Using complementation of a yeast mutant defective in regulation of metal transporters by cellular Zn status, we identified several members of the E2F1 transcription factor family in the heavy metal hyperaccumulator, Thlaspi caerulescens that are candidates for this role in plants. We currently are characterizing T-DNA knockouts of these genes in Arabidopsis with regards to changes in Zn-related phenotypes. Gene profiling analysis also will be used to identify genome-wide alterations in gene expression in these knockouts and these results will be presented.