Manganese accumulation and foliar distribution in the Australian
hyperaccumulators Gossia bidwillii and Gossia acmenoides
The known manganese (Mn) hyperaccumulator Gossia bidwillii, and G.
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 elucidate in situ distribution
patterns of Mn and other elements in hydrated G. 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. bidwillii accumulated
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.