Recently it has been demonstrated that Si nutrition can alleviate Fe deficiency chlorosis in cucumber (Cucumis sativus) by enhancing acquisition and root-to-shoot translocation of Fe. Here, Pavlovic et al. show that Si induces Fe mobilization in older (sink) leaves and increases its retranslocation to younger (source) leaves.

The proposed model of Si-mediated alleviation of Fe deficiency in cucumber.
The proposed model of Si-mediated alleviation of Fe deficiency in cucumber. Image by Pavlovic et al. (2016)

In older leaves, Si enhanced expression of NAS1 transcripts responsible for an increased tissue concentration of Fe chelator nicotianamine (NA). This was paralleled by an increased expression of the YSL1 transporter and hence more efficient movement of Fe-NA complex from source to sink leaves via the phloem.