Analysis of selenium accumulation, speciation and tolerance of potential selenium hyperaccumulator Symphyotrichum ericoides. Issue 1 (12th February 2014)

• Record Type: Journal Article
• Authors: El Mehdawi, Ali F.; Reynolds, Ray Jason B.; Prins, Christine N.; Lindblom, Stormy D.; Cappa, Jennifer J.; Fakra, Sirine C.; Pilon‐Smits, Elizabeth A.H.
• Is Part Of: Physiologia plantarum. Volume 152:Issue 1(2014:Sep.)
• Page Start: 70
• Page End: 83
• Publication Date: 2014-02-12
• Subjects: Plant physiology -- Periodicals; 571.2
• DOI: 10.1111/ppl.12149
• Languages: English
• ISSNs: 0031-9317

Abstract

<abstract abstract-type="main" id="ppl12149-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="ppl12149-para-0001"> <italic>Symphyotrichum ericoides</italic> was shown earlier to contain hyperaccumulator levels of selenium (Se) in the field (>1000 mg kg<sup>−1</sup> dry weight (DW)), but only when growing next to other Se hyperaccumulators. It was also twofold larger next to hyperaccumulators and suffered less herbivory. This raised two questions: whether <italic>S. ericoides</italic> is capable of hyperaccumulation without neighbor assistance, and whether its Se‐derived benefit is merely ecological or also physiological. Here, in a comparative greenhouse study, Se accumulation and tolerance of <italic>S. ericoides</italic> were analyzed in parallel with hyperaccumulator <italic>Astragalus bisulcatus</italic>, Se accumulator <italic>Brassica juncea</italic> and related Asteraceae <italic>Machaeranthera tanacetifolia</italic>. <italic>Symphyotrichum ericoides</italic> and <italic>M. tanacetifolia</italic> accumulated Se up to 3000 and 1500 mg Se kg<sup>−1</sup> DW, respectively. They were completely tolerant to these Se levels and even grew 1.5‐ to 2.5‐fold larger with Se. <italic>Symphyotrichum ericoides</italic> showed very high leaf Se/sulfur (S) and shoot/root Se concentration ratios, similar to <italic>A. bisulcatus</italic> and higher than <italic>M. tanacetifolia</italic> and <italic>B. juncea</italic>. Se X‐ray absorption near‐edge structure spectroscopy showed that <italic>S. ericoides</italic> accumulated Se predominantly (86%) as C‐Se‐C compounds indistinguishable from methyl‐selenocysteine, which may explain its Se tolerance. <italic>Machaeranthera tanacetifolia</italic> accumulated 55% of its Se as C‐Se‐C compounds; the remainder was inorganic Se. Thus, in this greenhouse study <italic>S. ericoides</italic> displayed all of the characteristics of a hyperaccumulator. The larger size of <italic>S. ericoides</italic> when growing next to hyperaccumulators may be explained by a physiological benefit, in addition to the ecological benefit demonstrated earlier.</p> </abstract>