Foliar Mn accumulation in eastern Australian herbarium specimens: prospecting for 'new' Mn hyperaccumulators and potential applications in taxonomy.
OBJECTIVE
The analysis of herbarium specimens has previously been used to prospect for 'new' hyperaccumulators, while the use of foliar manganese (Mn) concentrations as a taxonomic tool has been suggested. On the basis of their geographic and taxonomic affiliations to known Mn hyperaccumulators, six eastern Australian genera from the Queensland Herbarium collection were sampled for leaf tissue analyses.


METHODS
ICP-OES was used to measure Mn and other elemental concentrations in 47 species within the genera Austromyrtus, Lenwebbia, Gossia (Myrtaceae), Macadamia (Proteaceae), Maytenus and Denhamia (Celastraceae).


RESULTS
The resulting data demonstrated (a) up to seven 'new' Mn hyperaccumulators, mostly tropical rainforest species; (b) that one of these 'new' Mn hyperaccumulators also had notably elevated foliar Ni concentrations; (c) evidence of an interrelationship between foliar Mn and Al uptake among the Macadamias; (d) considerable variability of Mn hyperaccumulation within Gossia; and (e) the possibility that Maytenus cunninghamii may include subspecies.


CONCLUSIONS
Gossia bamagensis, G. fragrantissima, G. sankowsiorum, G. gonoclada and Maytenus cunninghamii were identified as 'new' Mn hyperaccumulators, while Gossia lucida and G. shepherdii are possible 'new' Mn hyperaccumulators. Of the three Myrtaceae genera examined, Mn hyperaccumulation appears restricted to Gossia, supporting its recent taxonomic revision. In the context of this present investigation and existing information, a reassesment of the general definition of Mn hyperaccumulation may be warranted. Morphological variation of Maytenus cunninghamii at two extremities was consistent with variation in Mn accumulation, indicating two possible 'new' subspecies. Although caution should be exercised in interpreting the data, surveying herbarium specimens by chemical analysis has provided an effective means of assessing foliar Mn accumulation. These findings should be followed up by field studies.
Fernando
Denise R
DR
School of Botany, The University of Melbourne, VIC 3010, Australia. denisef@unimelb.edu.au
Guymer
Gordon
G
Reeves
Roger D
RD
Woodrow
Ian E
IE
Baker
Alan J
AJ
Batianoff
George N
GN
D001315:Australia; D008345:Manganese / Q000378:metabolism*; D010802:Phylogeny; D018515:Plant Leaves / Q000378:metabolism*; D010944:Plants / Q000145:classification / Q000378:metabolism*; D013045:Species Specificity
D008345:Manganese