BORON-ISOTOPE FRACTIONATION IN PLANTS

Naturally-occurring variations in the abundance of stable isotopes of carbon, nitrogen, oxygen, and other elements in plants have been repor ted and are now used to understand various physiological processes in plants. Boron (B) isotopic variation in several plant species has been documented, but no determination as to whether plants fractionate the stable isotopes of boron, B-11 and B-10, has been made. Here, we repo rt that plants with differing B requirements (wheat, corn and broccoli ) fractionated boron. The whole plant was enriched in B-11 relative to the nutrient solution, and the leaves were enriched in B-11 and the s tem in B-11 relative to the xylem sap. Although at present, a mechanis tic role for boron in plants is uncertain, potential fractionating mec hanisms are discussed.