Characterization and benefits of selenium uptake by an Astragalus hyperaccumulator and a non-accumulator

Abstract

Background and Aims We characterized the relationship between soil and leaf concentrations of selenium in a hyperaccumulator and a non-accumulator to test the hypothesis that hyperaccumulators take up selenium while non-accumulators exclude it. We examined plant performance metrics and the ability of selenium to protect against herbivory by spider mites. Methods Known hyperaccumulator and non-accumulator species within the genus Astragalus were grown under a range of selenium concentrations and measured for tissue selenium, extent of herbivory, and vigor. Results Both hyperaccumulators and non-accumulators either failed to meet even the lenient threshold or exceeded even the strict threshold for hyperaccumulation depending on soil concentration. Both had decreased herbivory with increasing leaf selenium, and both grew larger at higher levels of selenium regardless of herbivory, despite a negative impact of higher relative uptake. Conclusions The relationships between selenium dosage and tissue concentrations matched only some model predictions. Under these conditions, the bioconcentration factor was a better delimiter between species than the absolute tissue concentration. We provide evidence that despite the apparent cost of uptake, selenium can enhance the growth of hyperaccumulators even when herbivory is not a significant factor. We propose the term Belemental stimulation^for this phenomenon.

Nickel hyperaccumulation by Streptanthus polygaloides is associated with herbivory tolerance

“…1) in high-Ni soil. Our results support the ''elemental stimulation'' hypothesis of Statwick et al (2016) since soil Ni enhanced both plant growth and reproductive success in S. polygaloides.…”

“…Elemental defense has become one of the best-supported hypotheses for the function of hyperaccumulation (for review, see Boyd 2007), however, other evolutionary drivers, including a direct benefit of a hyperaccumulated element, may act in concert with elemental defense. Statwick et al (2016) examined plant performance variables of the Se hyperaccumulator Astragalus bisulcatus (Hook.) A.…”

Dual Role of Metallic Trace Elements in Stress Biology—From Negative to Beneficial Impact on Plants

“…Besides, the adventageous effect of Cr application on biomass and/or photosynthesis efficiency was shown for taxonomically diversified species, such as Allium cepa [113], Jatropha curcas [114], Theobroma cacao [115], and Lemna minuta [116]. Further, Astragalus cicer and A. bisulcatus responded positively on Se dosage manifesting in the aboveground mass increase [117]. A similar increase in biomass production and in the root-shoot ratio was reported in Symplocos paniculata [118], whereas growth improvement occurred concomitantly in Camelia sinensis with an enhanced rate of net CO 2 -assimilation, chlorophyll a , and carotenoids content, as well as the concentration of carbohydrate and free amino acid compounds in young leaves [119].…”

Phytoremediation: green technology for improving aquatic and terrestrial environments

“…The final report of that study indicates that; plant foliage is the main volatilization part and the rate of Se volatilization has a high correlation with daytime. Comparing accumulator and non-accumulator plant for selenium volatilization were recently investigated by Statwick et al (2016). Volatilization of selenium is highly depended on soil microbial communities.…”