Revisiting Fe/S interplay in tomato: A split-root approach to study the systemic and local responses

Single and Combined Fe and S Deficiency Differentially Modulate Root Exudate Composition in Tomato: A Double Strategy for Fe Acquisition?

“…Despite previous studies widely demonstrating that root exudation is a fundamental tool adopted by plants to directly shape the rhizosphere favoring the root Fe acquisition [34,47,48], the knowledge about the root exudation pattern of S-deficient plants is rather limited. Furthermore, although the relationship between Fe and S uptake has been clearly demonstrated [11][12][13][14][15], to the best of our knowledge information concerning the exudation profiles of plants exposed to single S deficiency or combined Fe and S deficiency is still missing. Interestingly, Astolfi et al [49] demonstrated that S starvation strongly limits the release of PSs in Fe-deficient barley plants, suggesting that the intracellular S levels most likely have an impact on the qualitative and quantitative root exudation pattern.…”

“…Moreover, the identification/characterization of the sensing and signalling pathways activated in crops (as a consequence of the nutrients availability fluctuations is equally fundamental. In this respect, the mutual interaction between Fe and S has been clearly demonstrated in a wide variety of crops [11][12][13][14][15] and it was shown to have impacts at both the acquisition and assimilation levels. Regarding the latter, it is worth mentioning the Fe biofortification of wheat grain achieved through overfertilization with sulfate [16].…”

“…It has been clearly shown that root exudates are involved in both adaptative mechanisms (FeIII-reduction-based Strategy I of dicots and FeIII-PS complexes-based Strategy II of grasses) developed by plants in order to guarantee the Fe homeostasis in the different tissues [31] and some studies have shown that the composition of root exudates can change significantly as a function of the diverse levels of Fe availability [32][33][34][35]. However, despite the mutual interaction between Fe and S being well documented for the uptake mechanisms of the respective nutrients [11][12][13][14][15], to our knowledge there are still no indications regarding the role of this phenomenon in the exudate composition. From a general point of view, it is reasonable to hypothesize an effect of the variable S availability on the exudative pattern of roots with consequent adjustments to the organic compound fluxes in the soil.…”

Physiological Responses to Fe Deficiency in Split-Root Tomato Plants: Possible Roles of Auxin and Ethylene?

“…After 2 weeks of low Fe availability (5 µM Fe 3+ -EDTA), the root apparatus of each plant was divided into two approximately equal parts and separated into two compartments (split-root system); each compartment was filled with 1 L NS, containing different Fe concentrations, i.e., 40 µM Fe 3+ -EDTA or 40 µM 57 Fe-EDTA for the Fe-sufficient (+Fe) and 0 µM for Fe-deficient (-Fe) condition (Figure 1A). The choice of the experimental cultivation scheme was based on our previous work [62].…”

“…The plants were cultured in the split-root system for 1 week in order to induce Fe deficiency response, as shown in Figure 1B, according to our previous work [62]. On the sixth day, plants were treated with N-1-naphthylphthalamic acid (NPA), the inhibitor of the polar transport of auxin, and aminoethoxyvinylglycine (AVG), inhibitor of ethylene synthesis (Figure 1B).…”