Foliar Mn accumulation in eastern Australian herbarium specimens: prospecting for ‘new’ Mn hyperaccumulators and potential applications in taxonomy

Abstract

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.

Multiple metal accumulation within a manganese‐specific genus

“…Leaf chemical analyses ( Table 1 ) confi rmed existing knowledge ( Bidwell et al, 2002 ;Fernando et al, 2009 ) that: (a) Gossia software package ( Ryan et al, 1995 ;Ryan, 2001 ). As an aid to interpreting elemental distributions relative to leaf anatomy, elemental distributions across leaf cross-sections were also obtained as intensity profi les taken across transect lines between and including the dermal layers.…”

“…Material -Certain species were selected here for fi eld sampling because previous chemical analysis of their herbarium leaf tissues had revealed their abilities to accumulate other metals in addition to Mn ( Fernando et al, 2009 ). They were selected from two sites as follows: (a) Since Gossia fragrantissima had been discovered to be a Mn hyperaccumulator with additional affi nity for Ni, it was regarded as useful for examining in-vivo foliar Mn and Ni co-localization; (b) G. hillii (Benth.)…”

“…A chemical survey of eastern Australian herbarium specimens ( Fernando et al, 2009 ) detailed aspects of these fl oras relevant to discussion on metallophytes. Most signifi cant was the discovery of several previously unknown Mn hyperaccumulators, and the observation that Mn-specifi city clearly delineates Gossia from its sister genera ( Lenwebbia and Austromyrtus ).…”

“…Unlike other metals hyperaccumulated by plants, Mn is integral to photosynthesis since it is directly involved in the water-splitting reaction, as well as additionally providing structural integrity to chloroplast lamellae and playing a role in harvesting light energy during photosynthesis ( Burnell, 1988 ;Loneragan, 1988 ;Taiz and Zeiger, 2002 ). Mn hyperaccumulators are predominantly woody species distributed in and near the Western Pacifi c region, particularly on the Mn-enriched substrates of eastern Australia and New Caledonia ( Baker and Brooks, 1989 ;Proctor et al, 1989 ;Bidwell et al, 2002 ;Xue et al, 2004 ;Mizuno et al, 2008 ;Yang, Deng, and Li, 2008 ;Fernando et al, 2009 ). The Myrtaceae and to a lesser extent Proteaceae families are signifi cant among Mn hyperaccumulators.…”

Overexpression of the PHO84 gene causes heavy metal accumulation and induces Ire1p-dependent unfolded protein response in Saccharomyces cerevisiae cells

“…There are few plants that hyperaccumulate Mn from both contaminated soils (1% Mn) or from soils with normal concentration (Reeves 2006). Such plants are predominantly woody (Fernando et al 2008(Fernando et al , 2009 and hence unsuited to short-term controlled study. The use of friendly microorganisms as an alternative for hyperaccumulating plants is therefore an attractive possibility, and engineered yeast cells may be the organisms of choice.…”