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ISRN Botany
Volume 2013 (2013), Article ID 952043, 22 pages
http://dx.doi.org/10.1155/2013/952043
Review Article

Modulating Plant Calcium for Better Nutrition and Stress Tolerance

Department of Plant Biology, North Carolina State University, P.O. Box 7612, Raleigh, NC 27695, USA

Received 10 January 2013; Accepted 2 February 2013

Academic Editors: M. Adrian, E. Collakova, G. T. Maatooq, I. Paponov, and K. Takeno

Copyright © 2013 Dominique (Niki) Robertson. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

External Ca2+ supplementation helps plants to recover from stress. This paper considers genetic methods for increasing Ca2+ to augment stress tolerance in plants and to increase their nutritional value. The transport of Ca2+ must be carefully controlled to minimize fluctuations in the cytosol while providing both structural support to new cell walls and membranes, and intracellular stores of Ca2+ for signaling. It is not clear how this is accomplished in meristems, which are remote from active transpiration—the driving force for Ca2+ movement into shoots. Meristems have high levels of calreticulin (CRT), which bind a 50-fold excess of Ca2+ and may facilitate Ca2+ transport between cells across plasmodesmatal ER. Transgenes based on the high-capacity Ca2+-binding C-domain of CRT1 have increased the total plant Ca2+ by 15%–25% and also increased the abiotic stress tolerance. These results are compared to the overexpression of sCAX1, which not only increased total Ca2+ up to 3-fold but also caused Ca2+ deficiency symptoms. Coexpression of sCAX1 and CRT1 resolved the symptoms and led to high levels of Ca2+ without Ca2+ supplementation. These results imply an important role for ER Ca2+ in stress tolerance and signaling and demonstrate the feasibility of using Ca2+-modulating proteins to enhance both agronomic and nutritional properties.