Metal hyperaccumulation patterns within Plantago phylogeny (Plantaginaceae)

Abstract

We aimed to evaluate the presence of the metal hyperaccumulation trait in the phylogeny of Plantago with emphasis on P. subgen. Coronopus. Considering that P. almogravensis is an Al-hyperaccumulator and that phylogenetic links have been described for other Al-hyperaccumulators, we hypothesized that we would find more Plantago taxa with this accumulation trait. We also enquired if other metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn), follow a similar accumulation pattern as Al. We analysed metal accumulation data from direct (analyses) and indirect sources (bibliographic) combined with phylogenetic analysis. Regarding metal accumulation, our results indicate a high probability of hyperaccumulation in Plantago species (nine out of 15 species), namely for the metals Al (6–8), Cu (1), Zn (2–3) and Pb (1). There are also records of Fe (5) considered abnormally high. For P. subgen. Coronopus, hyperaccumulation was perceived in six out of seven species. In particular for Al-hyperaccumulation, a high frequency and dispersion among Plantago sub-ranks is compatible with a phylogenetic relation. Our work suggests that the Al-hyperaccumulation trait is common in Plantago, especially in P. subgen. Coronopus, and contributes to the scarce knowledge of that uncommon trait, namely in Mediterranean plants.