- • Little is known about the spatial distribution of excess manganese (Mn) in the leaves of tolerant plants. Recently, the first such study of a Mn hyperaccumulator showed that the highest localized Mn concentrations occur in the photosynthetic tissue. This is in contrast to reports based on localization of foliar accumulation of other heavy metals.
- • Here, four tree species, Gossia bidwillii, Virotia neurophylla, Macadamia integrifolia and Macadamia tetraphylla, which hyperaccumulate or strongly accumulate Mn, were studied. Cross-sectional foliar Mn localization was carried out in situ using proton-induced X-ray emission/energy dispersive X-ray analysis (PIXE/EDAX).
- • All four species contained photosynthetic tissues with multiple palisade layers. These were shown to be the primary sequestration sites for Mn. Mn was not detected in the epidermal tissues.
- • The findings of this study demonstrate a concurrence of three traits in four tree species, that is, accumulation of excess Mn in the leaves, its primary sequestration in the photosynthetic tissues, and multiple-layer palisade mesophyll.