Glutathione-dependent redox homeostasis is critical for chlorothalonil detoxification in tomato leaves.

Glutathione plays a critical role in plant growth, development and response to stress. It is a major cellular antioxidant and is involved in the detoxification of xenobiotics in many organisms, including plants. However, the role of glutathione-dependent redox homeostasis and associated molecular mechanisms regulating the antioxidant system and pesticide metabolism remains unclear. In this study, endogenous glutathione levels were manipulated by pharmacological treatments with glutathione synthesis inhibitors and oxidized glutathione. The application of oxidized glutathione enriched the cellular oxidation state, reduced the activity and transcript levels of antioxidant enzymes, upregulated the expression level of nitric oxide and Ca2+ related genes and the content, and increased the residue of chlorothalonil in tomato leaves. Further experiments confirmed that glutathione-induced redox homeostasis is critical for the reduction of pesticide residues. RNA sequencing analysis revealed that miRNA156 and miRNA169 that target transcription factor SQUAMOSA-Promoter Binding Proteins (SBP) and NUCLEAR FACTOR Y (NFY) potentially participate in glutathione-mediated pesticide degradation in tomato plants. Our study provides important clues for further dissection of pesticide degradation mechanisms via miRNAs in plants.

Jasmonic acid promotes glutathione assisted degradation of chlorothalonil during tomato growth.

Glutathione (GSH) biosynthesis and regeneration play a significant role in the metabolism of chlorothalonil (CHT) in tomatoes. However, the specific regulatory mechanism of GSH in the degradation of CHT remains uncertain. To address this, we investigate the critical regulatory pathways in the degradation of residual CHT in tomatoes. The results revealed that the detoxification of CHT residue in tomatoes was inhibited by buthionine sulfoximine and oxidized glutathione pretreatment, which increased by 26% and 46.12% compared with control, respectively. Gene silencing of γECS, GS, and GR also compromised the CHT detoxification potential of plants, which could be alleviated by GSH application and decreased the CHT accumulation by 33%, 25%, and 21%, respectively. Notably, it was found that the jasmonic acid (JA) pathway participated in the degradation of CHT regulated by GSH. CHT residues reduced by 28% after application of JA. JA played a role downstream of the glutathione pathway by promoting the degradation of CHT residue in tomatoes via nitric oxide signaling and improving the gene expression of antioxidant and detoxification-related enzymes. This study unveiled a crucial regulatory mechanism of GSH via the JA pathway in CHT degradation in tomatoes and offered new insights for understanding residual pesticide degradation.

Synthesis, crystal structures and magnetic properties of a series of chair-like heterometallic [Fe4Ln2] (Ln = GdIII, DyIII, HoIII, and ErIII) complexes with mixed organic ligands.

Four chair-like hexanuclear Fe-Ln complexes containing mixed organic ligands, namely, [Fe4Ln2{(py)2CO2}4(pdm)2(NO3)2(H2O)2Cl4]·xCH3CN·yH2O (Ln = GdIII (1, x = 1, y = 0), DyIII (2, x = 1, y = 1), HoIII (3, x = 0, y = 2), and ErIII (4, x = 1, y = 3); (py)2CO2H2 = the gem-diol form of di-2-pyridyl ketone and pdmH2 = 2,6-pyridinedimethanol) have been obtained by employing di-2-pyridyl ketone and 2,6-pyridinedimethanol reacting with FeCl3 and Ln(NO3)3 in MeCN. The structures of 1-4 are similar to each other except for the number of lattice solvent molecules. Four FeIII and two LnIII in these complexes comprise a chair-like core with the "body" constructed by four FeIII ions and the "end" constructed by two LnIII ions. Among the four compounds, 2 shows field-induced single molecule magnet behavior as revealed by ac magnetic susceptibility studies, with the effective energy barrier and the pre-exponential factor of 22.07 K and 8.44 × 10-7 s, respectively. Ab initio calculations indicated that, among 2_Dy, 3_Ho and 4_Er fragments, the energy gap between the lowest two spin-orbit states for 2_Dy is the largest, while the tunneling gap for 2 is the smallest. These might be the reasons for complex 2 exhibiting SMM behavior. Additionally, the orientations of the magnetic anisotropy of DyIII in 2 were obtained by electrostatic calculations and ab initio calculations, both indicating that the directions of the main magnetic axis of Dy1 ions are almost aligned along Dy1-O5 (O5 from the pdm2- ligand).

Two unprecedented decanuclear heterometallic [MnMnLn] (Ln = Dy, Tb) complexes displaying relaxation of magnetization.

We report the syntheses, crystal structures, and magnetic properties of two 3d-4f heterometallic compounds; namely, [Mn8Ln2O2(OH)2{(py)2CO2}4(teaH)4(CH3COO)6]·6CH3CN·2H2O (LnIII = Dy (1), Tb (2); (py)2CO2H2 = the gem-diol form of di-2-pyridyl ketone, teaH3 = triethanolamine). Both compounds were prepared by the reaction of Mn(OAc)2·4H2O, Ln(NO3)3·5H2O (Ln = Dy and Tb) with the ligands di-2-pyridyl ketone and triethanolamine in MeCN, and they crystallize in the monoclinic space group C2/c. [Mn8Ln2] complexes have not been reported before, and the metallic cores of both complexes were unprecedented. In these cores, two Dy or Tb and two Mn ions comprised a well-known butterfly topology, with three of the remaining six Mn atoms each being situated on either side of the butterfly, linked through two µ3-O2- ions. Six MnIII and two MnII were in six-coordinated distorted octahedrons and two LnIII ions were in nine-coordinated distorted muffins. Interestingly, the coordination sites of LnIII ions are occupied by six O and two N atoms from two teaH2- ligands and one µ3-O2- atom, without the presence of coordinated solvent molecules such as H2O and small anions such as NO3- ions, which is rare in 3d-4f complexes. Remarkably, alternating current (ac) magnetic susceptibility measurements revealed that both complexes displayed dynamic anisotropic magnetic behaviour. The effective energy barrier (Ueff) of complex 2 was estimated to be 18.97 K through high frequency (111-9111 Hz) ac susceptibility measurements. The low symmetry of the coordination configuration of Ln3+ in 1 and 2 may be responsible for the small energy barriers of these two compounds.

[Salt resistance of different tomato genotypes at seed germination stage].

Based on the cluster analysis of relative germination potential and relative germination rate under NaCl stress, fourteen tomato genotypes were clustered into two groups. Five tomato genotypes held high resistance to NaCl stress, and nine tomato genotypes were moderately NaCl- tolerant. The highly NaCl- tolerant genotypes wild Lycopersicon pimpinellifolium, Liaoyuanhongmanao and Hongbaoshi and the moderately NaCl- tolerant genotype Liaoyuanhongduoli were then under different Na(+)-salts and NaCl, Na+, and Cl- stresses. The responses of the four tomato genotypes to different Na(+)-salts stress were the same as those to NaCl stress. Among the test Na(+)-salts, NaHCO3 had the greatest impact. Under the stress of 100 mmol NaHCO3 x L(-1), the embryo's relative lengths of the four tomato genotypes were all below 8%. The inhibitory effect of test Na(+)-salts on tomato seed germination was in the order of NaNO3 < Na2SO4 < NaH2PO4 < NaCl < NaHCO3. As for NaCl, Na+ and Cl-, the Cl- had the smallest injury.

[Effects of salicylic acid on sucrose metabolism of tomato seedlings under NaCl stress].

A water culture experiment was conducted with the seedlings of tomato (Lycopersicon esculentum Mill.) cultivar Liaoyuanduoli to study the effects of salicylic acid (SA) on their sucrose metabolism under NaCl stress. The seedlings were treated with different concentrations (100, 300, and 500 mg x L(-1)) of SA, and the contents of sucrose, glucose, and fructose as well as the related enzyme activities of sucrose metabolism, including acid invertase (AI), neutral invertase (NI), sucrose phosphate synthase (SPS), and sucrose synthase (SS), in seedling leaves were determined. Under NaCl stress, SA could maintain or enhance the leaf fructose and glucose contents and the leaf AI, NI, SPS and SS activities, with the highest increment of fructose and glucose contents being 30.0% and 31.1% and that of AI, NI, SPS and SS activities being 24.7%, 27.9%, 22.0% and 24.5%, respectively, in comparing with no SA application, while had less effect on the leaf sucrose content, which suggested that SA could play a protective role in the NaCl-tolerance of tomato seedlings via enhancing the leaf invertase activity to increase leaf fructose and glucose contents. The best alleviating effect was observed at 500 mg x L(-1) of SA.