Phloem transport of arsenic species from flag leaf to grain during grain filling
Article first published online: 10 JUN 2011
© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust
Volume 192, Issue 1, pages 87–98, October 2011
How to Cite
Carey, A.-M., Norton, G. J., Deacon, C., Scheckel, K. G., Lombi, E., Punshon, T., Guerinot, M. L., Lanzirotti, A., Newville, M., Choi, Y., Price, A. H. and Meharg, A. A. (2011), Phloem transport of arsenic species from flag leaf to grain during grain filling. New Phytologist, 192: 87–98. doi: 10.1111/j.1469-8137.2011.03789.x
- Issue published online: 2 SEP 2011
- Article first published online: 10 JUN 2011
- Received: 29 March 2011, Accepted: 3 May 2011
- grain filling;
- •Strategies to reduce arsenic (As) in rice grain, below concentrations that represent a serious human health concern, require that the mechanisms of As accumulation within grain be established. Therefore, retranslocation of As species from flag leaves into filling rice grain was investigated.
- •Arsenic species were delivered through cut flag leaves during grain fill. Spatial unloading within grains was investigated using synchrotron X-ray fluorescence (SXRF) microtomography. Additionally, the effect of germanic acid (a silicic acid analog) on grain As accumulation in arsenite-treated panicles was examined.
- •Dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA) were extremely efficiently retranslocated from flag leaves to rice grain; arsenate was poorly retranslocated, and was rapidly reduced to arsenite within flag leaves; arsenite displayed no retranslocation. Within grains, DMA rapidly dispersed while MMA and inorganic As remained close to the entry point. Germanic acid addition did not affect grain As in arsenite-treated panicles. Three-dimensional SXRF microtomography gave further information on arsenite localization in the ovular vascular trace (OVT) of rice grains.
- •These results demonstrate that inorganic As is poorly remobilized, while organic species are readily remobilized, from leaves to grain. Stem translocation of inorganic As may not rely solely on silicic acid transporters.