Roots of Iron-Efficient Maize also Absorb Phytosiderophore-Chelated Zinc

Abstract

To investigate the recognition of Zn-phytosiderophores by the putative Fe-phytosiderophore transporter in maize (Zea mays L.) roots, short-term uptake of 65Zn-labeled phytosiderophores was compared in the Fe-efficient maize cultivar Alice and the maize mutant ys1 carrying a defect in Fe-phytosiderophore uptake. In ys1, uptake and translocation rates of Zn from Zn-phytosiderophores were one-half of those in Alice, but no genotypical difference was found in Zn uptake and translocation from other Zn-binding forms. In ys1 and in tendency also in Alice, Zn uptake decreased with increasing stability constant of the chelate in the order: ZnSO4 [greater than or equal to] Zn-desferrioxamine > Zn-phytosiderophores > Zn-EDTA. Adding a 500-fold excess of free phytosiderophores over Zn to the uptake solution depressed Zn uptake in ys1 almost completely. In uptake studies with double-labeled 65Zn-14C-phytosiderophores, ys1 absorbed the phytosiderophore at similar rates when supplied as a Zn-chelate or the free ligand. By contrast, in Alice 14C-phytosiderophore uptake from the Zn-chelate was 2.8-fold higher than from the free ligand, suggesting that Alice absorbed the complete Zn-phytosiderophore complex via the putative plasma membrane transporter for Fe-phytosiderophores. We propose two pathways for the uptake of Zn from Zn-phytosiderophores in grasses, one via the transport of the free Zn cation and the other via the uptake of nondissociated Zn-phytosiderophores.

Increased Abundance of Proteins Involved in Phytosiderophore Production in Boron-Tolerant Barley

“…The increased rate of leaf Zn accumulation supported the notion that Fe deficiency resulted in an increase in siderophore production, supporting the recent demonstration of the involvement of MA-related compounds in the uptake of Zn (von Wiren et al, 1996;Suzuki et al, 2006). Notably, high B alone had no effect on leaf Zn levels (Fig.…”

Can silicon partially alleviate micronutrient deficiency in plants? a review

“…This causes damage to membranes, membrane proteins, chlorophyll and enzymes, resulting in leaf chlorosis and the inhibition of photosynthesis and growth (Cakmak 2000). Similarly to Fe(III), which has even lower solubility, Zn solubility in the rhizosphere should be controlled through growth media acidification and low-molecular-weight chelating agents excretion by roots (Sinclair and Krämer 2012;von Wiren et al 1996). However, some authors consider that the enhancement of Zn soil availability induced by root changes not seem to play a key role in Zn efficiency mechanism and that Zn-efficient genotypes utilize Zn more efficiently through enzymes such as Cu/ZnSOD and carbonic anhydrase (Hacisalihoglu and Kochian 2003).…”

Hydrolysed wool: a novel soil amendment for zinc and iron biofortification of wheat

“…Therefore, through the application of hydrolysed wool, it is likely that Zn and Fe were applied to the soil in a complexed and phytoavailable form. These Zn-and Fe-amino acid complexes may enter the root and be taken up by the plant, just as in the case of Zn-phytosiderophore complexes which have been shown to be partly taken up as entire complexes (vonWiren et al 1996;White & Broadley 2009). In our experiment, WH-induced mobilization was inferred in the case of Fe, whereas the effect was small for Zn.…”