Abstract
The known manganese (Mn) hyperaccumulator Gossia bidwillii , andG. acmenoides unknown to hyperaccumulate Mn are tree species
native to subtropical eastern Australia, where they co-occur on Mn-rich
soils. Here, we investigate Mn accumulation and distribution in G.
acmenoides collected from its natural habitat, and propagated G.
bidwillii plants in a Mn dosing trial. Gossia bidwillii were
subjected to different levels of Mn (250 µg g-1, 500
µg g-1, 1000 µg g-1) treatments
whereas G. acmenoides were sampled from Mn rich soil. We used
laboratory-based X-ray Florescence Microscopy (XFM) to elucidatein situ distribution patterns of Mn and other elements in
hydratedG.
acmenoides and G. bidwillii tissues. Data from G.
acmenoides revealed that contrary to existing knowledge, it can be
strongly Mn-hyperaccumulating, with foliar Mn concentrations of 39 000
µg g-1 and 24 000 µg g-1 in old and
young leaves, respectively. In the Mn dosing trial, G. bidwilliiaccumulated 24 400 µg g-1 in old leaves and 17 100 µg
g-1 in young leaves at the highest treatment level.
The XFM data revealed clear interspecies differences in foliar Mn
distribution patterns, with wild G . acmenoides leaves
uniformly enriched throughout the laminae and petioles of both young and
old leaves; while in G. bidwillii , the foliar Mn distribution was
primarily concentrated at the apex and lamina. The approach employed of
combining data from the field and controlled experiments was especially
effective for comparing Mn accumulation in these two species and gaining
added insight into the phenomenon of Mn hyperaccumulation.