Broccoli serves as a functional food because it can accumulate selenium (Se), well-known bioactive amino-acid-derived secondary metabolites, and polyphenols. The chemical and physical properties of Se are very similar to those of sulfur (S), and competition between sulfate and selenate for uptake and assimilation has been demonstrated. Towards an efficient agronomic fortification of broccoli florets, the working questions were whether we could overcome this competition by exogenously applying the S-containing amino acids cysteine (Cys) or/and methionine (Met), or/and the precursors of Glucosinolate (GSL) types along with Se application. Broccoli plants were cultivated in a greenhouse and at the beginning of floret growth, we exogenously applied sodium selenate in the concentration gradient of 0, 0.2, 1.5, and 3.0 mM to study the impact of increased Se concentration on the organic S (S_org) content of the floret. The Se concentration of 0.2 mM (Se0.2) was coupled with the application of Cys, Met, their combination, or a mixture of phenylalanine, tryptophane, and Met. The application took place through fertigation or foliar application (FA) by adding isodecyl alcohol ethoxylate (IAE) or a silicon ethoxylate (SiE) surfactant. Fresh biomass, dry mass, and Se accumulation in florets were evaluated, along with their contents of S_org, chlorophylls (Chl), carotenoids (Car), glucoraphanin (GlRa), glucobrassicin (GlBra), glucoiberin (GlIb), and polyphenols (PPs), for the biofortification efficiency of the three application modes. From the studied selenium concentration gradient, the foliar application of 0.2 mM Se using silicon ethoxylate (SiE) as a surfactant provided the lowest commercially acceptable Se content in florets (239 μg or 0.3 μmol g⁻¹ DM); it reduced S_org (−45%), GlIb (−31%), and GlBr (−27%); and it increased Car (21%) and GlRa (27%). Coupled with amino acids, 0.2 mM Se provided commercially acceptable Se contents per floret only via foliar application. From the studied combinations, that of Met,Se0.2/FA,IAE provided the lowest Se content per floret (183 μg or 0.2 μmol g⁻¹ DM) and increased S_org (35%), Car (45%), and total Chl (27%), with no effect on PPs or GSLs. Cys,Met,Se0.2/FA,IAE and amino acid mix,Se0.2/FA,IAE increased S_org content, too, by 36% and 16%, respectively. Thus, the foliar application with the IAE surfactant was able to increase S_org, and methionine was the amino acid in common in these treatments, with varying positive effects on carotenoids and chlorophylls. Only the Cys,Met,Se0.2 combination presented positive effects on GSLs, especially GlRa, but it reduced the fresh mass of the floret. The foliar application with SiE as a surfactant failed to positively affect the organic S content. However, in all studied combinations of Se 0.2 mM with amino acids, the Se content per floret was commercially acceptable, the yield was not affected, the content of GSLs was increased (especially that of GlRa and GlIb), and PPs were not affected. The content of GlBr decreased except for the treatment with methionine (Met,Se0.2/FA,SiE) where GlBr remained unaffected. Hence, the combination of Se with the used amino acids and surfactants can provide enhanced biofortification efficiency in broccoli by providing florets as functional foods with enhanced functional properties.

Wheat possesses inherently low concentrations and bioavailability of the essential micronutrients (EMis) zinc (Zn), iron (Fe), manganese (Mn), and copper (Cu), limiting its capacity to sufficiently address human nutritional requirements. Biofortification of wheat with EMis through agricultural methods is a strategy aimed at addressing EMi deficiencies in human populations that emphasize cost-effectiveness and sustainability. All EMis are usually applied foliarly as sulfates, which indicates sulfur (S)-assisted biofortification. The formation of EMi complexes provides solubility as well as protection during long-distance transport. Several small molecules are possible candidates as ligands—the S-containing amino acids cysteine and methionine among them—linking EMi homeostasis to S homeostasis, which represents another aspect of S-assisted biofortification. In this study, we delve into the S-assisted agronomic biofortification strategy by applying sulfate micronutrients coupled with a sulfur-containing amino acid and we explore the effect of the selected accompanying cation (Zn, Fe, Mn, or Cu) on the EMi metallome of the grain, along with the biofortification effectiveness, whilst the type of the incorporated surface active agent seems to affect this approach. A field experiment was conducted for two years with durum wheat cultivation subjected to various interventions at the initiation of the dough stage, aiming to biofortify the grain with EMis provided as sulfate salts coupled with cysteine or methionine as potential biofortification enhancers. The mixtures were applied alone or in combination with commercial surfactants of the organosilicon ethoxylate (SiE) type or the alcohol ethoxylate (AE) type. The performance of two relevant preparations, FytoAmino-Bo (FABo) and Phillon, has been studied, too. The interventions affected the accumulation of the EMi metallome into the grains, along with the interactions of the EMis within this metallome. Several interventions increased the EMi metallome of the grain and affected the contribution of each EMi to this metallome. Many interventions have increased Zn and Fe, while they have decreased Mn and Cu. An increase in Zn corresponded (i) to a decrease in Cu, (ii) to an increase or no increase in Fe, and (iii) to a variable change in Mn. Cys increased the metallome by 34% and Zn and Fe within it. ZnSO₄ and FeSO₄ increased the metallome by 5% and 9%, whilst MnSO₄ and CuSO₄ increased the metallome by 36% and 33%, respectively. The additives improved the contribution to increasing the metallome in most cases. Without surfactant, the efficacy ranking proved to be MnSO₄ > CuSO₄ > ZnSO₄ > FeSO₄. The use of SW7 sustained the order CuSO₄ > MnSO₄ > ZnSO₄ > FeSO₄. The use of Saldo switched the order to CuSO₄ > ZnSO₄ > FeSO₄ > MnSO₄. In the case of Phillon, the order was CuSO₄ > FeSO₄ > ZnSO₄ > MnSO₄. The effect of Cys or Met was case-specific. The differentiations in the intensity of both the agronomic performance (grain weight, grain weight per spike, and yield) and the biofortification performance (concentrations vs. accumulations of each EMi within the grain) among the various combinations of EMis and additives are depicted by adopting a grading scale, which highlighted the intensity of the acclimation reaction of the biofortified grain to the applied intervention.

Iron (Fe) is an essential micronutrient for plant development and productivity. Nevertheless, the role of gibberellins (GAs) in the control of iron homeostasis is less studied compared to other growth regulators. We found that GAs modulate iron homeostasis in maize by inducing deficiency-like responses independent of rhizosphere iron availability. Plant phenotyping demonstrated that exogenous GA₃ application under iron-sufficient conditions phenocopied iron deprivation, while inhibiting GA biosynthesis with mepiquat chloride prevented the development of typical symptoms of Fe deficiency (–Fe). Gibberellins positively control strategy II Fe uptake genes, albeit indirectly, as opposed to the direct negative transcriptional regulation of phytosiderophore biosynthesis. Additionally, gibberellins disrupt iron partitioning by suppressing root-to-shoot Fe translocation, causing iron overaccumulation in roots of GA₃ treated plants. A functional ferrous iron uptake pathway was identified and was found to operate in conjunction with the strategy II uptake pathway via the differentially regulated Zea mays Iron-Regulated Transporter (IRT) paralogs ZmIRT1 and ZmIRT2. Root responses are spatially organized: gene expression in the lateral root sector reflects the shoot iron status, while transcriptional responses in the root apex correlate with local Fe demands. This study demonstrates that maize leverages a hybrid ferric/ferrous iron uptake strategy and establishes novel roles of GAs as pivotal regulators of iron homeostasis.

A cultivation of durum wheat that established in a field with soil poor in micronutrients received foliar applications at the initiation of the dough stage towards biofortifying the spikes with micronutrients. The morphology of the spike is crucial in determining grain yield, and the spikelets, the components of the inflorescence, influence each other. The number and arrangement of these spike components affect spike length, spike weight, spike chaff (the non-grain biomass in the spike), grain number per spike, grain weight per spike, and spikelet number per spike, and all contribute to final grain yield per spike. The spike’s developmental program responded to the interventions regarding the morphological traits; this response was analyzed for each spike component, and an acclimation program seemed to be activated by each intervention. Cysteine or methionine has been added as a potential enhancer of the biofortification process, and the application mixtures were coupled with selected surfactants, an organosilicon ethoxylate or an alcohol ethoxylate one, while products with targeted composition for biofortification with micronutrients have also been studied. Their effect on the developmental acclimation program of the treated spike is presented and discussed. The action of this program provided grains of similar weight, regardless of the intervention.

Cellular carbon (C) and nitrogen (N) metabolisms are tightly coordinated towards sustaining optimal growth and development for plants. C:N ratio is well-studied. Research results highlight strong interest in C:N dynamics in crops, especially in relation to soil health, crop production, as well as nutrient cycling. However, the C:N:S (sulfur) stoichiometry within plant tissues is under-reviewed. This lack of research persists despite the critical importance of the C:N:S elemental nexus for nutrient use efficiency, stress physiology, yield quality, and sustainable fertilization. Thus, the biochemical integration of C, N, and S and the corresponding homeostases are discussed. Moreover, the C:N:S:Fe (iron) elemental nexus appears to possess strategic contribution, given the close functional relationship between S and Fe. This interaction is increasingly vital as environmental stressors, particularly nutrient imbalances and climate instability become urgent challenges in crop physiology. Moreover, erratic weather patterns alter nutrient availability and uptake, plant metabolism, and stoichiometric homeostasis. Consequently, we highlight the central role of C:N:S:Fe elemental nexus in maintaining crop performance under climate instability and discuss how plants integrate C, N, S, and Fe responses to environmental stressors.