Photosynthesis and growth of Amaranthus tricolor under strontium stress

Consumption of foods contaminated with heavy metals and their association with cardiovascular disease (CVD) using GAM software (cohort study)

Introduction

Heavy metals can enter the environment and food through industrial activities, acid rain, chemical fertilizers, pesticides, and sewage. A large amount of these metals is dangerous because they tend to bio accumulate. A concern with these metals is the long-term, low-dose exposure seen in the general population. HMs can cause disorders in the cardiovascular system through various mechanisms such as the production of free radicals, DNA damage, lipid peroxidation, and oxidative stress.

Material and method

Food items measured in the present study included rice, bread, and vegetables. 210 participants (105 controls and 105 patients) were randomly selected for this study. The demographic information of the subjects was obtained from the Hoveyzeh Cohort Center. The relationship between heavy metals in food and cardiovascular diseases is investigated by The Generalized Additive Model (GAM).

Result

The results of the present study showed that when urine Cd was smoothed based on rice Cd, there was a significant correlation between urine Cd and Cd consumed in vegetables and rice. The GAM coefficient for urinary Cd excreted in case-control groups and Cd consumed in vegetables were 479.79(SE: 6.49-73.87) and 818.56(SE: 11.96-68.43), respectively, and for rice consumed, it was 0.03(SE: 0.015-2.103) and 0.04(SE: 0.017-2.338), respectively. The GAM coefficient for As consumption in vegetables and As in urine of case and control groups was 1.61 (SE: 9.48-0.16) and 22.36 (SE: 13.60-1.64), respectively. The same coefficient for rice consumption in case and control groups was 4.5 (SE: 0.62-7.22) and 10.48 (SE: 1.46-7.16), respectively. There was a very strong and significant correlation between the Sr in the urine of both groups and the Sr in the food consumed, so that the urinary Sr in the control group is excreted more than in the cardiovascular group.

Conclusion

GAM analysis indicates that As in vegetable and rice is more than the standard limitation value. Also, Sr and Cd in vegetables, rice, and bread were more than the standard limitation value. According to the GAM model As had a significant value in rice and vegetables indicating that As is more than the standard limitation value, therefore, it is associated with CVD.

Genome-Wide Identification and Expression Analysis under Abiotic Stress of BrAHL Genes in Brassica rapa

The AT-hook motif nuclear localized (AHL) gene family is a highly conserved transcription factor critical for the growth, development, and stress tolerance of plants. However, the function of the AHL gene family in Brassica rapa (B. rapa) remains unclear. In this study, 42 AHL family members were identified from the B. rapa genome and mapped to nine B. rapa chromosomes. Two clades have formed in the evolution of the AHL gene family. The results showed that most products encoded by AHL family genes are located in the nucleus. Gene duplication was common and expanded the BrAHL gene family. According to the analysis of cis-regulatory elements, the genes interact with stress responses (osmotic, cold, and heavy metal stress), major hormones (abscisic acid), and light responses. In addition, the expression profiles revealed that BrAHL genes are widely expressed in different tissues. BrAHL16 was upregulated at 4 h under drought stress, highly expressed under cadmium conditions, and downregulated in response to cold conditions. BrAHL02 and BrAHL24 were upregulated at the initial time point and peaked at 12 h under cold and cadmium stress, respectively. Notably, the interactions between AHL genes and proteins under drought, cold, and heavy metal stresses were observed when predicting the protein-protein interaction network.

Contrasting Responses and Phytoremediation Potential of Two Poplar Species to Combined Strontium and Diesel Oil Stress

The soil pollution caused by diesel oil and heavy metals has become an increasingly serious environmental issue, with negative global-scale impacts. The remediation of contaminated soil requires special attention, in which phytoremediation has emerged as an ecofriendly solution. However, the response of plants to the combined stress of diesel oil and heavy metals remains largely unknown. In this study, the aim was to investigate the potential of Populus alba and P. russkii for phytoremediation by examining their response to combined diesel oil and heavy metal stress. In a greenhouse experiment using soil contaminated with 15 mg kg^-1 of diesel oil and varying concentrations of Sr (0, 10, or 100 mg kg^-1), we studied the physiological and biochemical changes, as well as the Sr absorption, of P. alba and P. russkii. The results showed that at high concentrations of Sr and diesel oil, the growth of both species was substantially inhibited, but P. alba exhibited higher resistance due to its higher antioxidant enzyme activities and increased accumulation of soluble sugar and proline. Additionally, P. alba concentrated Sr in the stem, whereas P. russkii accumulated Sr in the leaf, exacerbating its negative effects. Diesel oil treatments were beneficial for Sr extraction due to cross-tolerance. Our findings indicate that P. alba is more suitable for the phytoremediation of Sr contamination due to its superior tolerance to combined stress, and we identified potential biomarkers for monitoring pollution. Therefore, this study provides a theoretical basis and implementation strategy for the remediation of soil contaminated by both heavy metals and diesel oil.

AMF Inoculation Alleviates Molybdenum Toxicity to Maize by Protecting Leaf Performance

The use of arbuscular mycorrhizal fungi (AMF) is a vital strategy for enhancing the phytoremediation of heavy metals. However, the role of AMF under molybdenum (Mo) stress is elusive. A pot culture experiment was conducted to explore the effects of AMF (Claroideoglomus etunicatum and Rhizophagus intraradices) inoculation on the uptake and transport of Mo and the physiological growth of maize plants under different levels of Mo addition (0, 100, 1000, and 2000 mg/kg). AMF inoculation significantly increased the biomass of maize plants, and the mycorrhizal dependency reached 222% at the Mo addition level of 1000 mg/kg. Additionally, AMF inoculation could induce different growth allocation strategies in response to Mo stress. Inoculation significantly reduced Mo transport, and the active accumulation of Mo in the roots reached 80% after inoculation at the high Mo concentration of 2000 mg/kg. In addition to enhancing the net photosynthetic and pigment content, inoculation also increased the biomass by enhancing the uptake of nutrients, including P, K, Zn, and Cu, to resist Mo stress. In conclusion, C. etunicatum and R. intraradices were tolerant to the Mo stress and could alleviate the Mo-induced phytotoxicity by regulating the allocation of Mo in plants and improving photosynthetic leaf pigment contents and the uptake of nutrition. Compared with C. etunicatum, R. intraradices showed a stronger tolerance to Mo, which was manifested by a stronger inhibition of Mo transport and a higher uptake of nutrient elements. Accordingly, AMF show potential for the bioremediation of Mo-polluted soil.

Photosynthetic regulation in response to strontium stress in moss Racomitrium japonicum L

Strontium (Sr²⁺) pollution and its biological effects are of great concern including photosynthetic regulation, which is fundamental to environmental responses, especially for bryophytes during their terrestrial adaptation. Alternative electron flows mediated by flavodiiron proteins (FLVs) and cyclic electron flow (CEF) in photosystem I (PSI) are crucial to abiotic stresses moss responses; however, little is known about the moss photosynthesis regulation under nuclide treatment. We measured chlorophyll fluorescence parameters in PSI, photosystem II (PSII) and the P700 redox state, oxidative stress in the moss Racomitrium japonicum under low (5 mg/L), moderate (50 mg/L) and high (500 mg/L) Sr²⁺ stress level. Moderate and high Sr²⁺ stress triggered H₂O₂ and malondialdehyde (MDA) generation, and catalase (CAT) activity increases, which are involved in reactive oxygen species regulation. The significant PSII photochemistry (Fv/Fm), Chla/chlb, Y(I)/Y(II), Y(NA), Y(ND) and ETRI-ETRII decreases at moderate and high Sr²⁺, and the Y(I), Y(II) decreases at high Sr²⁺ revealed the photo-inhibition and photo-damage in PSI and PSII by moderate and high Sr²⁺ stress. The nonphotochemical quenching (NPQ) increased significantly at moderate and high Sr²⁺ stress, reflecting a heat-dissipation-related photo-protective mechanism in antenna system and reaction centers. Moreover, rapid re-oxidation of P700 indicated that FLV-dependent flows significantly regulated PSI redox state under moderate and high Sr²⁺ stress. and CEF upregulation was found at low Sr²⁺. Finally, photosynthetic acclimation to Sr²⁺ stress in R. japonicum was linked to FLVs and CEF adjustments.