An Iron Transporter Is Involved in Iron Homeostasis, Energy Metabolism, Oxidative Stress, and Metacyclogenesis in Trypanosoma cruzi

The parasite Trypanosoma cruzi causes Chagas’ disease; both heme and ionic Fe are required for its optimal growth, differentiation, and invasion. Fe is an essential cofactor in many metabolic pathways. Fe is also harmful due to catalyzing the formation of reactive O2 species; for this reason, all living systems develop mechanisms to control the uptake, metabolism, and storage of Fe. However, there is limited information available on Fe uptake by T. cruzi. Here, we identified a putative 39-kDa Fe transporter in T. cruzi genome, TcIT, homologous to the Fe transporter in Leishmania amazonensis and Arabidopsis thaliana. Epimastigotes grown in Fe-depleted medium have increased TcIT transcription compared with controls grown in regular medium. Intracellular Fe concentration in cells maintained in Fe-depleted medium is lower than in controls, and there is a lower O2 consumption. Epimastigotes overexpressing TcIT, which was encountered in the parasite plasma membrane, have high intracellular Fe content, high O2 consumption—especially in phosphorylating conditions, high intracellular ATP, very high H2O2 production, and stimulated transition to trypomastigotes. The investigation of the mechanisms of Fe transport at the cellular and molecular levels will assist in elucidating Fe metabolism in T. cruzi and the involvement of its transport in the differentiation from epimastigotes to trypomastigotes, virulence, and maintenance/progression of the infection.

Enrichment of Zinc and Iron Micronutrients in Lentil (Lens culinaris Medik.) through Biofortification

Biofortification of pulse crops with Zn and Fe is a viable approach to combat their widespread deficiencies in humans. Lentil (Lens culinaris Medik.) is a widely consumed edible crop possessing a high level of Zn and Fe micronutrients. Thus, the present study was conducted to examine the influence of foliar application of Zn and Fe on productivity, concentration, uptake and the economics of lentil cultivation (LL 931). For this, different treatment combinations of ZnSO4·7H2O (0.5%) and FeSO4·7H2O (0.5%), along with the recommended dose of fertilizer (RDF), were applied to the lentil. The results of study reported that the combined foliar application of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at pre-flowering (S1) and pod formation (S2) stages was most effective in enhancing grain and straw yield, Zn and Fe concentration, and uptake. However, the outcome of this treatment was statistically on par with the results obtained under the treatment ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage. A single spray of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage enhanced the grain and straw yield up to 39.6% and 51.8%, respectively. Similarly, Zn and Fe concentrations showed enhancement in grain (10.9% and 20.4%, respectively) and straw (27.5% and 27.6% respectively) of the lentil. The increase in Zn and Fe uptake by grain was 54.8% and 68.0%, respectively, whereas uptake by straw was 93.6% and 93.7%, respectively. Also the benefit:cost was the highest (1.96) with application of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage. Conclusively, the combined use of ZnSO4·7H2O (0.5%) + FeSO4·7H2O (0.5%) at S1 stage can contribute significantly towards yield, Zn and Fe concentration, as well as uptake and the economic returns of lentil to remediate the Zn and Fe deficiency.

The Effect of the Upregulated Expression of Fe Regulators IMA1 and bHLH104 in Arabidopsis on the Root Length and Fe Homeostasis Under Pi Starvation

Phosphate (Pi) and iron (Fe) are two essential mineral nutrients for plant growth and development. Pi starvation triggers the Fe local redistribution and over-accumulation, resulting in the reduction of the primary root, while represses the expression of Fe uptake genes. Nevertheless, the antagonistic mechanism between P and Fe nutrition in plant remain not addressed. Here, the effect of the upregulated expression of Fe regulators IMA1 and bHLH104 driven by the different-type promoters (proCaMV 35S, the promoters of Pi-starvation responsive genes proIPS1 and proPHT1;4) in response to Pi starvation was investigated in Arabidopsis. The results showed that the expression of Fe uptake genes IRT1 and FRO2 was successfully upregulated in proIPS1::IMA1, proPHT1;4::IMA1 and proIPS1::bHLH104 under Pi starvation while decreased in pro35S::IMA1, pro35S::bHLH104 and proPHT1;4::bHLH104, compared with that in the corresponding plants under Pi sufficiency. Although the length and Fe distribution in roots of them didn’t have significant difference with wild type under Pi starvation, the Fe distribution and total Fe contents were significantly increased in shoots of proIPS1::IMA1, proPHT1;4::IMA1 and proIPS1::bHLH104 while were decreased in proPHT1;4::bHLH104. The higher Fe concentrations in the Pi-starved transgenic plants also conferred the obviously tolerance to Fe deficiency. Their biomasses and total P concentrations showed no difference with wild type, regardless of Pi sufficiency or deficiency. Therefore, this approach would be a novel manipulation to modify Fe nutrient via coupling with Pi starvation in plants.

Challenges and opportunities to regulate mineral transport in rice

Iron (Fe) is an essential mineral for plants and its deficiency as well as toxicity severely affects plant growth and development. Although Fe is ubiquitous in mineral soils, its acquisition by plants is difficult to regulate particularly in acidic and alkaline soils. Under alkaline conditions, where lime is abundant, Fe and other mineral elements are sparingly soluble. In contrast, under low pH conditions, especially in paddy fields, Fe toxicity could occur. Fe uptake is complicated and could be integrated with copper (Cu), manganese (Mn), zinc (Zn), and cadmium (Cd) uptake. Plants have developed sophisticated mechanisms to regulate the Fe uptake from soil and its transport to root and above-ground parts. Here, we review recent developments in understanding metal transport and discuss strategies to effectively regulate metal transport in plants with a particular focus on rice.

MNB1 gene is involved in regulating the iron-deficiency stress response in Arabidopsis thaliana

Abstract Iron (Fe) is an indispensable mineral element for normal growth of plants. Fe deficiency induces a complex series of responses in plants, involving physiological and developmental changes, to increase Fe uptake from soil. However, the molecular mechanism involved in plant Fe-deficiency is not well understood. Here, we found that the MNB1 gene is involved in modulating Fe-deficiency response in Arabidopsis thaliana . The expression of MNB1 was inhabited by Fe-deficiency stress. Knockout of MNB1 led to enhanced Fe accumulation and tolerance, whereas the MNB1-overexpressing plants were sensitive to Fe-deficiency stress. Lower H 2 O 2 concentrations in mnb1 mutant plants were examined under Fe deficiency circumstances compared to wild-type. On the contray, higher H 2 O 2 concentrations were found in MNB1-overexpressing plants, which was adversely linked with malondialdehyde (MDA) concentrations. Furthermore, in mnb1 mutants, the transcription level of the Fe-uptake and translocation genes, FIT , IRT1 , FRO2 , Z IF , FRD3 , NAS4 , PYE and MYB72 , were considerably elevated during Fe-deficiency stress, resulting in higher Fe accumulation. Together, our findings show that the MNB1 gene negatively controls the Fe-deficiency response in Arabidopsis via modulating reactive oxygen species (ROS) levels and the ROS-mediated signaling pathway, thereby affecting the expression of Fe-uptake and translocation genes.

Impact of green clay authigenesis on K–Mg–Fe sequestration in marine settings

Retrograde clay mineral reactions (i.e., reverse weathering), including glauconite formation, are first-order controls on element (re)cycling vs sequestration in modern and ancient marine sediments. Here, we report substantial K–Mg–Fe sequestration by glauconite formation in shallow marine settings from the Triassic to the Holocene, averaging 4 ± 3 mmol K·cm−²·kyr− 1, 4 ± 2 mmol Mg·cm−²·kyr− 1 and 10 ± 6 mmol Fe·cm−²·kyr− 1, which is ~ 2 orders of magnitude higher compared to deep-sea settings. Upscaling of glauconite abundances in shallow-water (< 200 m) environments predicts a global K–Mg–Fe uptake of ~ 0.05–0.06 Tmol K·yr− 1, ~ 0.04–0.06 Tmol Mg·yr− 1 and ~ 0.11–0.14 Tmol Fe·yr− 1. We conclude that authigenic clay elemental uptake had a large impact on the global marine K, Mg and Fe cycles throughout Earth`s history, in particular during ‘greenhouse’ periods with sea level highstand. Quantifying authigenic clay formation is key for better understanding past and present geochemical cycling in marine sediments.

Acetic Acid-Producing Endophyte Lysinibacillus fusiformis Orchestrates Jasmonic Acid Signaling and Contributes to Repression of Cadmium Uptake in Tomato Plants

Diverse signaling pathways regulated by phytohormones are essential for the adaptation of plants to adverse environments. Root endophytic bacteria can manipulate hormone-related pathways to benefit their host plants under stress conditions, but the mechanisms underlying endophyte-mediated plant stress adaptation remain poorly discerned. Herein, the acetic acid-producing endophytic bacteria Lysinibacillus fusiformis Cr33 greatly reduced cadmium (Cd) accumulation in tomato plants. L. fusiformis led to a marked increase in jasmonic acid (JA) content and down-regulation of iron (Fe) uptake-related genes in Cd-exposed roots. Accordantly, acetic acid treatment considerably increased the JA content and inhibited root uptake of Cd uptake. In addition, the Cr33-inoculated roots displayed the increased availability of cell wall and rhizospheric Fe. Inoculation with Cr33 notably reduced the production of nitric oxide (NO) and suppressed Fe uptake systems in the Cd-treated roots, thereby contributing to hampering Cd absorption. Similar results were also observed for Cd-treated tomato plants in the presence of exogenous JA or acetic acid. However, chemical inhibition of JA biosynthesis greatly weakened the endophyte-alleviated Cd toxicity in the plants. Collectively, our findings indicated that the endophytic bacteria L. fusiformis effectively prevented Cd uptake in plants via the activation of acetic acid-mediated JA signaling pathways.

Supraoptimal Iron Nutrition of Brassica napus Plants Suppresses the Iron Uptake of Chloroplasts by Down-Regulating Chloroplast Ferric Chelate Reductase

Iron (Fe) is an essential micronutrient for plants. Due to the requirement for Fe of the photosynthetic apparatus, the majority of shoot Fe content is localised in the chloroplasts of mesophyll cells. The reduction-based mechanism has prime importance in the Fe uptake of chloroplasts operated by Ferric Reductase Oxidase 7 (FRO7) in the inner chloroplast envelope membrane. Orthologue of Arabidopsis thaliana FRO7 was identified in the Brassica napus genome. GFP-tagged construct of BnFRO7 showed integration to the chloroplast. The time-scale expression pattern of BnFRO7 was studied under three different conditions: deficient, optimal, and supraoptimal Fe nutrition in both leaves developed before and during the treatments. Although Fe deficiency has not increased BnFRO7 expression, the slight overload in the Fe nutrition of the plants induced significant alterations in both the pattern and extent of its expression leading to the transcript level suppression. The Fe uptake of isolated chloroplasts decreased under both Fe deficiency and supraoptimal Fe nutrition. Since the enzymatic characteristics of the ferric chelate reductase (FCR) activity of purified chloroplast inner envelope membranes showed a significant loss for the substrate affinity with an unchanged saturation rate, protein level regulation mechanisms are suggested to be also involved in the suppression of the reduction-based Fe uptake of chloroplasts together with the saturation of the requirement for Fe.

Iron deficiency induced changes in Fe homeostasis and 14-3-3 interactomics of Arabidopsis thaliana

Members of 14-3-3 protein family are involved in the proper operation of Fe acquisition mechanisms at physiological and gene expression levels in Arabidopsis thaliana. To more directly and effectively observe whether members of 14-3-3 non-epsilon group have a function in Fe-deficiency adaptation, three higher order quadruple KOs, kappa/lambda/phi/chi (klpc), kappa/lambda/upsilon/nu(klun), and upsilon/nu/phi/chi (unpc) were generated and applied for physiological analysis in this study. The mutant plants that combine kl with un (klun) or kl with pc (klpc) mutations showed a better Fe uptake than Wt plants at low medium Fe, while this phenotype was absent in unpc mutant. The higher Fe uptake by klun correlated with a higher Fe-deficiency induced expression of selected Fe-related genes. The dynamics of 14-3-3-client interactions analysis showed that a subset of 27 proteins differentially interacted with 14-3-3 in roots caused by Fe deficiency. Many of these Fe responsive proteins have a role in glycolysis and TCA cycle, the FoF1-synthase and in the cysteine/methionine synthesis. Also, the 14-3-3 interactome of the klun roots showed significant differences with that of Wt roots under Fe sufficient conditions, where most of these differential binding proteins showed enhanced binding in the klun mutant. Nevertheless, a clear explanation for the observed phenotypes awaits a more detailed analysis of the functional aspects of 14-3-3 binding to the target proteins identified in this study.