Silicon increases iron use efficiency in cucumber – a strategy 1 model plant

Abstract

Silicon (Si) and iron (Fe) are respectively the second and the fourth most abundant minerals in the earth’s crust. While the essentiality of Fe has been discovered in the middle of the 19th century, Si is still not fully accepted as an essential element for higher plants. Due to poor Fe availability for higher plants, especially in alkaline and calcareous soils, Fe deficiency represents a major limiting factor for crop production worldwide, affecting both crop yield and quality, with a strong negative impact on human health. Here we investigated the key physiological, biochemical and molecular parameters involved in the processes of root acquisition and tissue utilization of Fe by cucumber (Cucumis sativus L.), as both Strategy 1 model and Si-accumulating species. Silicon nutrition increased the accumulation of apoplastic Fe and Fe-mobilizing compounds in roots, as well as upregulated the expression of genes (AHA1, FRO2, IRT1) encoding the main components of the reduction-based Fe uptake machinery (Pavlovic et al., 2013). In leaves, Si affected relative Fe distribution by enhancing Fe remobilization from old leaves via increased NA accumulation and expression of the YSL1, which stimulated Fe chelation and its retranslocation to younger leaves (Pavlovic et al., 2016). This for the first time demonstrated a new beneficial role of Si, i.e. in increasing nutrient acquisition, transport and utilization by crops. References: Pavlovic J., Samardzic J., Kostic L., Laursen K.H., Natic M., Timotijevic G., Schjoerring J.K., Nikolic M. (2016): Ann. Bot. 118, 271-280. Pavlovic J., Samardzic J., Maksimović V., Timotijevic G., Stevic N., Laursen K.H., Hansen T.H., Husted S., Schjoerring J.K., Liang Y., Nikolic M. (2013): New Phytol. 198, 1096-1107