Iron allocation in leaves of Fe‐deficient cucumber plants fed with natural Fe complexes

Abstract

Iron (Fe) sources available for plants in the rhizospheric solution are mainly a mixture of complexes between Fe and organic ligands, including phytosiderophores (PS) and water-extractable humic substances (WEHS). In comparison with the other Fe sources, Fe-WEHS are more efficiently used by plants, and experimental evidences show that Fe translocation contributes to this better response. On the other hand, very little is known on the mechanisms involved in Fe allocation in leaves. In this work, physiological and molecular processes involved in Fe distribution in leaves of Fe-deficient Cucumis sativus supplied with Fe-PS or Fe-WEHS up to 5 days were studied combining different techniques, such as radiochemical experiments, synchrotron micro X-ray fluorescence, real-time reverse transcription polymerase chain reaction and in situ hybridization. In Fe-WEHS-fed plants, Fe was rapidly (1 day) allocated into the leaf veins, and after 5 days, Fe was completely transferred into interveinal cells; moreover, the amount of accumulated Fe was much higher than with Fe-PS. This redistribution in Fe-WEHS plants was associated with an upregulation of genes encoding a ferric(III) -chelate reductase (FRO), a Fe(2+) transporter (IRT1) and a natural resistance-associated macrophage protein (NRAMP). The localization of FRO and IRT1 transcripts next to the midveins, beside that of NRAMP in the interveinal area, may suggest a rapid and efficient response induced by the presence of Fe-WEHS in the extra-radical solution for the allocation in leaves of high amounts of Fe. In conclusion, Fe is more efficiently used when chelated to WEHS than PS and seems to involve Fe distribution and gene regulation of Fe acquisition mechanisms operating in leaves.

New ‘solutions’ for floating cultivation system of ready-to-eat salad: A review

“…HS can be obtained from different sources (Halpern et al, 2015), however it is worth to note that interesting results on root proliferation and nutrient uptake have been obtained using low concentrations of water-soluble molecules isolated from peat Schmidt et al, 2007). Particularly, supplying plants with Fe complexed to water extractable humic substances led to a higher translocation of iron to the leaves, as compared to other Fe complexes (Tomasi et al , 2009Zanin et al, 2015); this effect might be relevant when considering alternatives to synthetic Fe-chelate as well as for biofortification programmes.…”

“…Most of the leaf vegetable products are actually minimally processed, packed in air or in modified atmosphere, refrigerated and consumed within 5e10 days from harvest (Rolle & Chism, 1987). Ready-to-use leaf vegetables are thus particularly requested by consumers for their quality, convenience, but also for the increased awareness about the relations between health status and consumption of fresh vegetable rich in phytochemicals with protecting capability (Zanin et al, 2009;Zanin et al, 2011). Based on these expectations, the sensory and nutritional qualities of fresh-cut vegetables are extremely important (Kader, 2008).…”

“…In fact, in these environments water, for its scarcity, price and quality, is becoming an economically scarce resource (Valenzano, Parente, Serio, & Santamaria, 2008), thus causing the replacement of a traditional agriculture by cultivation systems with higher water-use efficiency. Among the various suitable solutions, hydroponics in floatingsystem represents a valid alternative (van Os & Stanghellini, 2001) becoming in these last years the most diffused for the production of high-quality, fresh-cut vegetables like lettuce, endive, escarole, lamb lettuce, rocket, water cress, and also radish (Salerno et al, 2005;Zanin, Ponchia, Sambo, & Ortega, 2011). It is a quite simple device, developed independently by Massantini (1976) and Jensen and Collins (1985), consisting of a storage reservoir of recirculating nutrient solution arranged on a flat surface, like a pond, where plants, grown upon polystyrene rafts, are fed.…”

Determination of Micronutrient Accumulation in Greenhouse Cucumber Crop Using a Modeling Approach

“…Although there is a high availability of this element in the applied nutrient solution, the plants did not accumulate higher concentrations. This was probably because cucumber plants optimize the use of Fe when the source is chelated [36,37].…”

Iron oxide‐humic acid coprecipitates as iron source for cucumber plants

“…It has been clearly demonstrated that Fe complexed by low molecular weight water‐extractable humic fractions can be utilized by cucumber plants with an efficiency higher than that observed for other Fe sources, such as Fe‐ethylenediaminetetraacetic acid (EDTA), Fe‐Cl 3 , and Fe‐citrate ( Pinton et al, ). This effect was not only ascribed to the specific plant Fe acquisition mechanism at the root level ( Tomasi et al, ), but also to the mechanisms involved in the allocation of the nutrient at the leaf level ( Tomasi et al, , ; Zanin et al, ).…”