ARS | Publication request: A comparison of root iron acquisition capabilities in Carya aquatica and Carya illinoinensis

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 5, 2012
Publication Date: June 17, 2012
Citation: Grusak, M.A., Kroh, G.E., Grauke, L.J. 2012. A comparison of root iron acquisition capabilities in Carya aquatica and Carya illinoinensis [abstract]. Proceedings, XVI International Symposium on Iron Nutrition and interactions in Plants, June 17-21, 2012, Amherst, Massachusetts. p. 50.

Technical Abstract: Carya aquatica (water hickory) thrives in water-saturated soils where ferrous iron is prevalent. However, when grown in drier soils, this species exhibits iron deficiency. Carya illinoinensis (pecan), a closely related species to Carya aquatica, is generally iron-adequate when grown in non-flooded areas (i.e., oxygenated soils), where iron is found predominantly in the ferric form. When needed, both species utilize a root iron reductase enzyme to reduce ferric to ferrous iron, prior to the absorption of ferrous iron (i.e., both are Strategy I species). Because of the apparent differences in iron efficiency we have observed between these species, we hypothesized that either the iron reductase or the iron uptake capabilities of Carya aquatica might be lower, relative to pecan. Either possibility might be required to minimize iron toxicity in this species' normal habitat, while making it less adaptive in other soil environments. For these studies, we measured root iron reduction following hydroponic growth in Fe-replete or Fe-deficient conditions. Results showed that there was variation within and amongst different cultivars/ecotypes of both species; however, measured rates of iron reduction were not significantly different between the species. Root iron uptake was also measured in each species by a radio-labeled assay, using plants grown with iron-deficient (1 uM Fe[III]HEDTA) or iron-adequate (60 uM Fe[III]HEDTA) conditions. 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.