Silicon influence on plant ionome and mineral element transporters

Abstract

The plant ionomics is the study of essential and nonessential mineral element composition of plants (the ionom) at cellular, tissue or organismal level. The plant ionomic profile is affected by various factors, including plant (e.g. species, genotypes, organ, developmental change) and environment (e.g. soil, fertilizers, stress conditions). Over the past decade rapid progress has been made in understanding the mechanisms through which silicon (Si) mediates mineral excess and/or toxicity stress. However, the effect of Si on the mineral element uptake and consequently the plant ionome is still unclear, in particular under conditions of limited nutrient availability. Firstly, I will present recent results of my research group demonstrating that Si application modulates the ionomic profile of various plant species (e.g. rice, barley, wheat, maize, cucumber, sunflower, soybean, grapevine and tomato) grown under both normal and stress conditions. In the second part of my talk I will review the current knowledge of Si influence on the expression of (a) root and shoot metal transporter genes under excess of cadmium (Cd), manganese (Mn) and copper (Cu) (Li et al., 2018; Kim et al. 2014; Che et al., 2016; Farooq et al., 2016); (b) transporter genes involved in the uptake, long-distance transport and homeostasis of iron (Fe) under low Fe conditions (Pavlovic et al., 2013, 2016); (c) transporter genes for inorganic phosphorus (Pi) root uptake under low P conditions (Kostic et al., manuscript submitted); and (d) transporter genes involved in shoot homeostasis of sodium (Na+) (see Bosnic et al., this proceedings) and B (Akcay & Erkan, 2016) under saline stress. In conclusion, the role of Si in modulation of plant ionome, including also nutrient and other mineral element uptake and utilization, appears to be more indirect by transcriptional regulation of genes responsible for both root acquisition and tissue homeostasis. Further understanding of how exactly Si regulates the expression of mineral element transporter genes will help to improve crop productivity, yield quality and food safety in stress conditions.