The rapid accumulation of aluminum is ubiquitous in both the evergreen and deciduous leaves of Theaceae and Ternstroemiaceae plants over a wide pH range in acidic soils

Background and aims

Aluminum (Al) accumulator plants are occasionally found in certain genera or families of woody plant species that are broadly dispersed in the angiosperm phylogeny. However, spatial and seasonal patterns in Al accumulation within the closely related species of each group remain poorly understood.

Methods

We quantitatively monitored the internal Al levels of eight Theaceae and Ternstroemiaceae species growing on acidic soils at multiple sites.

Results

Among the eight species, seven other than Ternstroemia gymnanthera shared a rapid Al accumulation in the developing leaves. Species comparison revealed that Al accumulation in mature leaves saturates within a flushing year, regardless of differences in leaf structure, seasonality, and acidic soil pH (4.5–5.5) at multiple sites. In tall trees of Stewartia monadelpha, the Al contents of the leaves were constantly high irrespective of their height positions up to 12 m. Moreover, the Al content of the leaves was only slightly decreased in the last 2 weeks of autumn senescence, in which nitrogen (N) or phosphate (P) retranslocation had been completed.

Conclusion

These results suggest that most of the Theaceae and Ternstroemiaceae species possess an effective metal-transport mechanism that rapidly loads Al into the young leaves until each level reaches a species-specific threshold.