ARS | Publication request: A comparison of root iron uptake rates in Carya aquatica and Carya illinoinensis

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 27, 2011
Publication Date: March 2, 2012
Citation: Kroh, G.E., Grauke, L.J., Grusak, M.A. 2012. A comparison of root iron uptake rates in Carya aquatica and Carya illinoinensis [abstract]. Texas Academy of Sciences 115th Annual Meeting. p.52.

Technical Abstract: Carya aquatica (water hickory) thrives in water saturated soils, where ferrous iron predominates. However, this species exhibits iron deficiency when grown in drier soils. Carya illinoinensis (pecan) is generally iron-adequate when grown in non-flooded areas, where iron is found predominantly in the ferric form. When needed, Carya species use a root iron reductase enzyme to reduce ferric to ferrous iron, prior to the absorption of ferrous iron. Because previous studies have shown no major differences in root iron reductase capability between these two species, we questioned whether the apparent iron acquisition differences between them might be due to differences in ferrous iron uptake. Thus, we hypothesized that the iron uptake rate of water hickory would be lower, relative to pecan, because the potentially toxic ferrous iron is more readily available in water hickory’s preferred habitat. Furthermore, we hypothesized that plants grown in iron-deficient conditions (1 uM Fe[III]) would upregulate their iron uptake capacity relative to plants grown in iron-adequate conditions (60 uM Fe[III]). Root iron uptake was measured by a radio-labeled assay. While root iron uptake was significantly upregulated (2.6-fold) in iron-deficient pecans, relative to iron-adequate pecans, measured rates of iron uptake were similar between iron-adequate pecans and iron-adequate water hickory. Iron uptake measurements in iron-deficient water hickory are still in progress. We will use these results to discuss and compare the iron acquisition capabilities and habitat ecologies of these related species. This work was supported in part by a Texas Academy of Sciences Research Award to GEK.