Phylogenetic variation in heavy metal accumulation in angiosperms

The influence of phylogeny on shoot heavy metal content in plants was investigated and the hypothesis tested that traits impacting on the accumulation of cadmium, chromium, copper, nickel, lead and zinc in plant shoots are associated. Data suitable for comparative analyses were generated from a literature survey, using a residual maximum likelihood (REML) procedure. Both pair-wise regressions and principal components analyses (PCA) were performed on independent contrasts of shoot metal content. Significant variation in shoot metal content occurred at the classification level of order and above, suggesting an ancient evolution of traits. Traits impacting on the accumulation of metals in plant shoots were associated. This information can be used to improve predictions of soil-to-plant metal transfer, to formulate hypotheses on the origins of metal-accumulating phenotypes and to inform the exploitation of plant genetic resources for nutritional improvement and phytoremediation.