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Summary: Manganese (Mn) is an essential micronutrient in plants. However, excessive Mn absorption in acidic soils can cause Mn toxicity, which adversely affects plant growth and crop yields. At present, acidic soils cover c. 30% of the Earth's surface. However, the mechanism underpinning Mn uptake remains largely unknown.We identified cbl1/9 and cipk23 mutants exhibiting high‐Mn‐sensitive phenotype through the reverse genetics method. Furthermore, we identified the CIPK23 phosphorylated NRAMP1 through a variety of protein interaction techniques and protein kinase assays.Here, we demonstrated that two calcineurin B‐like proteins, CBL1/9, and their interacting kinase CIPK23 positively regulated the tolerance of Mn toxicity in Arabidopsis. The cbl1 cbl9 double mutant and cipk23 mutants exhibited high‐Mn‐sensitive phenotypes, which manifested as decreased primary root length, biomass, and chlorophyll concentration, and higher accumulation of Mn. In addition, CIPK23 interacted with and phosphorylated the Mn transporter NRAMP1 primarily at Ser20/22 in vitro and in vivo, and thereby induced clathrin‐mediated endocytosis of NRAMP1 to reduce its distribution on the plasma membrane and enhance plant tolerance to Mn toxicity.In summary, we found that the CBL1/9–CIPK23–NRAMP1 module regulates the tolerance to high‐Mn toxicity and provide insight into a mechanism of the tolerance of plants to Mn toxicity. [ABSTRACT FROM AUTHOR]

SUMMARY: Nitrogen (N) is one of the most essential mineral elements for plants. Brassinosteroids (BRs) play key roles in plant growth and development. Emerging evidence indicates that BRs participate in the responses to nitrate deficiency. However, the precise molecular mechanism underlying the BR signaling pathway in regulating nitrate deficiency remains largely unknown. The transcription factor BES1 regulates the expression of many genes in response to BRs. Root length, nitrate uptake and N concentration of bes1‐D mutants were higher than those of wild‐type under nitrate deficiency. BES1 levels strongly increased under low nitrate conditions, especially in the non‐phosphorylated (active) form. Furthermore, BES1 directly bound to the promoters of NRT2.1 and NRT2.2 to promote their expression under nitrate deficiency. Taken together, BES1 is a key mediator that links BR signaling under nitrate deficiency by modulating high affinity nitrate transporters in plants. Significance Statement: The accumulation of BES1 in the non‐phosphorylated state under low nitrogen conditions directly promotes their transcription by binding to the promoters of NRT2.1 and NRT2.2, thereby enhancing the uptake of NO3− in roots and improving the utilization efficiency of plants to nitrogen. The present study provides direct evidence that brassinosteroid signals are directly involved in the regulation of nitrogen uptake and nitrogen transporters. [ABSTRACT FROM AUTHOR]

Summary: Cadmium (Cd) is a toxic heavy element for plant growth and development, and plants have evolved many strategies to cope with Cd stress. However, the mechanisms how plants sense Cd stress and regulate the function of transporters remain very rudimentary.Here, we found that Cd stress induces obvious Ca2+ signals in Arabidopsis roots. Furthermore, we identified the calcium‐dependent protein kinases CPK21 and CPK23 that interacted with the Cd transporter NRAMP6 through a variety of protein interaction techniques.Then, we confirmed that the cpk21 23 double mutants significantly enhanced the sensitive phenotype of cpk23 single mutant under Cd stress, while the overexpression and continuous activation of CPK21 and CPK23 enhanced plants tolerance to Cd stress. Multiple biochemical and physiological analyses in yeast and plants demonstrated that CPK21/23 phosphorylate NRAMP6 primarily at Ser489 and Thr505 to inhibit the Cd transport activity of NRAMP6, thereby improving the Cd tolerance of plants.Taken together, we found a plasma membrane‐associated calcium signaling that modulates Cd tolerance. These results provide new insights into the molecular breeding of crop tolerance to Cd stress. [ABSTRACT FROM AUTHOR]

This study focuses on a black micro‐arc oxidation ceramic coating prepared on the surface of magnesium alloy by the technology of micro‐arc oxidation in the electrolyte containing F– and Fe3+ as well as its mechanism of F– and Fe3+. It needs coatings to experience detail analyses on their thickness, roughness, corrosion resistance, thermal control property, valence states of elements, phase composition, and morphology of coatings, respectively, through coating thickness gauge, roughness tester, electrochemical workstation, AE radiometer, X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), scanning electron microscope (SEM), and energy‐dispersive X‐ray spectroscopy (EDS). Results showed that with the help of F– in electrolyte, Fe3+ can be complexed and MgF2 can be obtained in the coating, which reduces the pores on the surface of micro‐arc oxidation coating. In addition, Fe3+ in the electrolyte contributes to the preparation of Fe2O3 and Fe3O4 in the coating, which can blacken the surface of the coating. Both F– and Fe3+ benefit to improve the corrosion resistance and thermal control performance of micro‐arc oxidation coating. There is higher iron oxide in the outer layer but higher fluoride in the inner layer of the coating. [ABSTRACT FROM AUTHOR]

Nitrogen (N) deficiency occurs in over 80% of karst soil of southwest China, which restricts regional agricultural production. To test whether N fixed by legumes becomes available to nonfixing companion species, N fluxes between soybean and maize under no, partial, and total restriction of root contact were measured on a karst site in southwest China. N content and its transfer between soybean and maize intercrops were explored in a 2-year plot experiment, with N movement between crops monitored using 15N isotopes. Mesh barrier (30 μm) and no restrictions barrier root separation increased N uptake of maize by 1.28%-3.45% and 3.2%-3.45%, respectively. N uptake by soybean with no restrictions root separation was 1.23 and 1.56 times higher than that by mesh and solid barriers, respectively. In the unrestricted root condition, N transfer from soybean to maize in no restrictions barrier was 2.34-3.02 mg higher than that of mesh barrier. Therefore, it was implied that soybean/maize intercropping could improve N uptake and transfer efficiently in the karst region of southwest China. [ABSTRACT FROM AUTHOR]