New insight into silica deposition in horsetail (Equisetum arvense)

BMC Plant Biology

Research Article

Christopher Exley¹  Chinnoi Law¹ 

[1] The Birchall Centre, Lennard-Jones Laboratories, Keele University, ST5 5BG, Staffordshire, UK;

关键词: Biosilicification;    biogenic silica;    silicic acid;    horsetails;    callose;    PDMPO;    fluorescence;    acid digestion.;   

DOI  :  10.1186/1471-2229-11-112

 received in 2011-04-15, accepted in 2011-07-29,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundThe horsetails (Equisetum sp) are known biosilicifiers though the mechanism underlying silica deposition in these plants remains largely unknown. Tissue extracts from horsetails grown hydroponically and also collected from the wild were acid-digested in a microwave oven and their silica 'skeletons' visualised using the fluor, PDMPO, and fluorescence microscopy.ResultsSilica deposits were observed in all plant regions from the rhizome through to the stem, leaf and spores. Numerous structures were silicified including cell walls, cell plates, plasmodesmata, and guard cells and stomata at varying stages of differentiation. All of the major sites of silica deposition in horsetail mimicked sites and structures where the hemicellulose, callose is known to be found and these serendipitous observations of the coincidence of silica and callose raised the possibility that callose might be templating silica deposition in horsetail. Hydroponic culture of horsetail in the absence of silicic acid resulted in normal healthy plants which, following acid digestion, showed no deposition of silica anywhere in their tissues. To test the hypothesis that callose might be templating silica deposition in horsetail commercially available callose was mixed with undersaturated and saturated solutions of silicic acid and the formation of silica was demonstrated by fluorimetry and fluorescence microscopy.ConclusionsThe initiation of silica formation by callose is the first example whereby any biomolecule has been shown to induce, as compared to catalyse, the formation of silica in an undersaturated solution of silicic acid. This novel discovery allowed us to speculate that callose and its associated biochemical machinery could be a missing link in our understanding of biosilicification.

【 授权许可】

CC BY   
© Law and Exley; licensee BioMed Central Ltd. 2011