Silicon alleviates iron deficiency in cucumber by promoting mobilization of iron in the root apoplast

Abstract

· Root responses to lack of iron (Fe) have mainly been studied in nutrient solution experiments devoid of silicon (Si). Here we investigated how Si ameliorates Fe deficiency in cucumber (Cucumis sativus) with focus on the storage and utilization of Fe in the root apoplast. · A combined approach was performed including analyses of apoplastic Fe, reduction-based Fe acquisition and Fe-mobilizing compounds in roots along with the expression of related genes. · Si-treated plants accumulated higher concentrations of root apoplastic Fe, which rapidly decreased when Fe was withheld from the nutrient solution. Under Fe-deficient conditions, Si also increased the accumulation of Fe-mobilizing compounds in roots. Si supply stimulated root activity of Fe acquisition at the early stage of Fe deficiency stress through regulation of gene expression levels of proteins involved in Fe acquisition. However, when the period of Fe deprivation was extended, these reactions further decreased as a consequence of Si-induced enhancement of the Fe status of the plants. · This work provides new evidence for the beneficial role of Si in plant nutrition and clearly indicates that Si-mediated alleviation of Fe deficiency includes an increase of the apoplastic Fe pool in roots and an enhancement of Fe acquisition.

Silicon induced Fe deficiency affects Fe, Mn, Cu and Zn distribution in rice (Oryza sativa L.) growth in calcareous conditions

“…6A). Similar results were observed in cucumber, but after the 468 first day of Fe deficiency, no differences regarding plant Si addition were observed 469 (Pavlovic et al, 2013). This lower apoplastic Fe concentration observed in root with Si 470 supply was accompanied by higher Fe translocation to shoot (Fig.…”

Can silicon partially alleviate micronutrient deficiency in plants? a review

“…However, its effect on metal deficiency has been less studied, although recently several authors focus their research on this topic (Gonzalo et al 2013;Pavlovic et al 2013;Bityutskii et al 2014). The effect of Si on micronutrient toxicity has been explained by either internal or external effects.…”

“…However, its effect on Fe deficiency has been less studied (Gonzalo et al 2013;Pavlovic et al 2013;Bityutskii et al 2014) especially in strategy I plants, and the reported experimental conditions were different among references. Iron toxicity has been effectively alleviated in rice after Si addition (Ma 2004;Fu et al 2012) mainly by an increase in the iron precipitation in the growth media or at root surfaces (iron plaque).…”

“…For cucumber plants, several short experiments in hydroponics were compiled in the recent literature (Pavlovic et al 2013;Gonzalo et al 2013;Bityutskii et al 2014), but the described experimental conditions differ greatly among studies. Pavlovic et al (2013) and Bityutskii et al (2014) tested two Si doses (0 and 1.5 mM), and Fe was supplied as Fe(III)-EDTA when added.…”

“…Pavlovic et al (2013) and Bityutskii et al (2014) tested two Si doses (0 and 1.5 mM), and Fe was supplied as Fe(III)-EDTA when added. The pH of nutrient solutions was 6.0.…”