Borer, Catherine H. , Scott, Claire E. .
Calcium partitioning and sequestration in plant foliage from White Sands National Monument, an extremely high-calcium site.
Calcium (Ca) is an essential macronutrient, but its concentration within the cytoplasm of all cells must be maintained at low levels to avoid Ca toxicity. This also allows Ca to be utilized as an important and ubiquitous second messenger, enabling cells to sense and respond to numerous environmental signals. Cellular partitioning and sequestration of Ca has been studied in Ca-deficient plants, but foliar partitioning in plants growing under conditions of excess Ca availability has not been studied in depth. Our purpose in this study was to assess whether a range of plant species that can tolerate a very high-Ca environment can chemically sequester excess Ca in a physiologically unavailable form, thus maintaining physiologically active forms of foliar Ca at reasonably low levels. We assessed Ca partitioning and sequestration in a variety of plant species growing at White Sands National Monument, a site with substrate consisting primarily of gypsum (calcium sulfate), resulting in very high availability of Ca for uptake by plants. Foliage was collected from both native and exotic invasive species including: Rhus trilobata, Populus fremontii, Yucca elata, Poliomintha incana, Tamarix gallica, and Allenrolfea occidentalis. Foliage samples were washed, flash-frozen, freeze-dried, and ground to a fine powder prior to analysis. Chemical components were separated by sequential acidic extractions, followed by Ca analysis using a colorimetric method. Grab samples of soil at each site were collected and assessed for plant available Ca, to verify the high-Ca conditions at each site. We found substantial variability among species in their ability to sequester the Ca they absorb, but perhaps more importantly, in their ability to prevent uptake and retention of Ca. This research project provides insights into the physiology of Ca sequestration in plants, and the physiological and ecological processes that occur in the unique ecosystems present at White Sands National Monument.
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1 - Berry College, Biology, P.O. Box 490430, Mount Berry, GA, 30149, USA
White Sands National Monument
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM