Excessive sulphur accumulation and ionic storage behaviour identified in species of Acacia (Leguminosae: Mimosoideae)

Thiophores, which are typically desert gypsophytes, accumulate high (2–6 % S dry weight) sulphur concentrations and may possess unique tolerance to environmental stress factors, e.g. sulphate/metal toxicity, drought and salinity. Little is known of the prevalence of the behaviour or the associated physiological aspects.

Reid et al. show a group of native Australian plants that exhibit thiophore behaviour. This behaviour is independent of substrate type, and present in all members of this related group of species. Other species in the same substrate do not show the same behaviour. The thiophores studied exhibit a tight coupling between sulphur and calcium uptake and storage, and apparently store these elements as inorganic salts within the cells in their foliage. Several of the thiophores occupy coastal or riparian habitats, suggesting the evolutionary and ecophysiological explanations for this trait do not lie solely in adaptation to arid conditions or gypsiferous soils.