Flowering plant phylogeny and soil to plant transfer of radionuclides

Centre for Research in Plant Science, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY, U.K.

Abstract

Our understanding of the evolutionary relationships (phylogenies) between flowering plants has been transformed in the last yen years. As a result, new phylogenies for flowering plants have been developed specifically for comparative biological studies. Researchers have used these new phylogenies to help explain variation in a number of plant characteristics. We have used them to help explain soil to plant transfer of heavy metal ions and have recently finished applying them to studies of soil to plant transfer of radionuclides. Using REML analyses we combined literature data and data from our own experiments to provide data bases of relative concentrations of ¹³⁷Cs, ⁶⁰Co, ³⁵S, ¹³¹I, ⁹⁰Sr, ³⁶Cl and ¹⁰⁹Ru in up to 200 plant taxa. Analysis of these databases using heirarchical ANOVAs showed that radionuclide concentration in plants is significantly affected by phylogeny. There are some similarities and differences in phylogenetic patterns between the different radionuclides. In particular, for many radionuclides concentrations in monocotyledonous plants are significantly lower than for other flowering plants. Certain plant orders including the Caryophyllales and Cucurbitales have a significant tendancy to accumulate radionuclides. The implications of these findings for understanding and predicting soil to plant transfer of radionuclides in a wide range of plant taxa will be discussed.