This study was designed to prepare bio-assisted Fe-based nanocomplexes (Fe-based NCs) using two different biological precursors, namely green tea extract (Fe-T NCs) and Kilka fish extract (Fe-F NCs), and to evaluate their physicochemical properties and effects on the foliar characteristics of Zataria multiflora Boiss. (Z. multiflora). The Fourier Transform Infrared (FTIR) spectroscopy showed that oxygen containing functional groups in green tea molecules and amide/carboxyl functional groups in Kilka molecules were responsible for Fe coordination and capping. The Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) observations indicated that Fe–T NCs exhibited a relatively more uniform morphology, whereas Fe–F NCs showed a more heterogeneous and aggregated structure. The biological assay indicated that 0.4% Fe-T NCs was the most effective foliar treatment, leading to marked improvements in vegetative growth, biomass production, chlorophyll accumulation, hydration status, membrane stability, and leaf structural traits. Oxidative stress was concurrently alleviated, evidenced by reduced hydrogen peroxide (H2O2) and malondialdehyde (MDA) accumulation and enhanced superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX) activities. The same treatment also maximized essential oil production and modified the oil profile, with thymol showing a notable increase. According to the principal component analysis (PCA) and correlation analyses, improved growth, water status, membrane integrity, antioxidant responses, and essential oil production were associated with lower oxidative stress markers. In summary, Fe-T NCs performed better than Fe-F NCs, possibly due to their polyphenol-associated surface chemistry, smaller particle size, and relatively improved colloidal behavior.
In the chloroplasts of angiosperms adapted to the same environment, the thylakoid system is assumed to present converging structural and functional characteristics. This assumption was tested for the example of two winter radicchio cultivars ‘Rosso di Chioggia precoce’ and ‘Rosso di Treviso precoce’, which have been adapted for many decades to the coastal environment at the Po River Delta, Italy. The photosynthetic electron and proton fluxes analysed by chlorophyll a fluorescence, P700 absorption and electrochromic bandshift, combined with quantitative ultrastructure, revealed the highly divergent regulatory strategies in the two cultivars to preserve photosystem integrity. ‘Rosso di Chioggia precoce’ relies on a high linear electron flow (LEF) capacity operating within a canonical grana-intergrana thylakoid architecture. Conversely, ‘Rosso di Treviso precoce’ compensates for a lower LEF by modulating its photosynthetic membrane properties, displaying reduced PSII connectivity, enlarged plastoquinone pool, enhanced cyclic electron flow (CEF) around PSI, and increased ATP synthesis. Unexpectedly, the enhanced PSI activity was uncoupled from the (I–P)/(J–P) amplitude ratio during fast fluorescence induction, and the thermal dissipation of excess absorbed energy (NPQ) remained low despite higher CEF. These functional discrepancies were explained by the spatial segregation of a PSI population into unconventional, circular single thylakoids. Such anomalous thylakoid architecture could reflect an incomplete physiological adaptation of ‘Rosso di Treviso precoce’ to coastal environmental pressures.
Selenium (Se) and sulfur (S) are well-known antioxidant elements and are involved in nutrient uptake (especially Zn) under sulfate salinity. Many studies report synergistic interactions between Se and S; however, the molecular mechanisms underlying Se's influence on metal uptake and transporters under sulfate salinity remain unclear. Therefore, this report is conceptualized to determine the expression level of metal transporters (prominently ZIP transporters) in maize, grown in a hydroponic system, by applying two Se levels (0 and 10 μM Na2SeO4) in combination with two Zn levels (0 and 0.5 μM ZnSO4) under different saline conditions (non-saline and 50 mM Na2SO4 salinity). Our results showed that, compared with Zn deficiency, Zn application increased Se and S concentrations in plants. The key novelty of this study is that Se induces some members of the ZIP transporter family (ZmZIP2, ZmZIP4, and ZmZIP5 in roots, whereas ZmZIP1, ZmZIP2, and ZmZIP4 in leaves) and heavy metal ATPase-3 in Zn-sufficient saline-grown plants compared with similarly treated Se-free plants. Under Zn-sufficiency, upregulation of these metal transporters increased mineral translocation via xylem sap and micronutrient uptake in plants under sulfate salinity (particularly in roots) compared with their non-saline counterparts. Our findings showed that, in the absence of Se, ZIP transporter expression and heavy metal ATPase expression remain unaltered under sulfate salinity. Taken together, we conclude that Se, combined with high sulfate availability, supports micronutrient translocation and uptake by markedly enhancing the expression of some ZIP transporter family members and HMA3 in SO42--salinized plants. These hydroponic-based findings provide transcriptomic-level evidence for ZIP transporters, suggesting a mechanistic pathway that highlights Se's beneficial role in metal transport. Accordingly, this experiment could be optimized for field conditions, as other soil-related factors are also involved. Therefore, further validation under soil conditions is needed.
Lignin is a major component of secondary cell walls and plays essential roles in mechanical support and stress resistance. In Heracleum moellendorffii Hance, a medicinal and aromatic plant resource under artificial cultivation, petioles undergo progressive firming and lignification during development. Here, we combined anatomical observation, cell-wall and biochemical measurements, metabolomics, transcriptomics, and heterologous functional analysis to characterize developmental lignification. Microscopic observations and firmness measurements revealed progressive structural changes accompanied by increased lignin deposition from the early to late developmental stages. Targeted metabolite analysis showed developmental remodeling of the monolignol-related metabolite pool, with the relative proportion of coniferyl alcohol increasing during petiole maturation. Integrated RNA-seq and metabolite analyses prioritized Hm4CL2, HmCCR2, and HmCAD2 as candidate structural genes associated with lignin biosynthesis. Stable heterologous expression of these genes in tobacco was associated with altered vascular anatomy and changes in measured monolignol-related compounds. These findings provide a developmental framework for lignification in H. moellendorffii and identify candidate genes for future manipulation of lignification, pending direct functional validation in this species.
