RESUMO
Ion homeostasis is essential for plant growth and environmental adaptation, and maintaining ion homeostasis requires the precise regulation of various ion transporters, as well as correct root patterning. However, the mechanisms underlying these processes remain largely elusive. Here, we reported that a choline transporter gene, CTL1, controls ionome homeostasis by regulating the secretory trafficking of proteins required for plasmodesmata (PD) development, as well as the transport of some ion transporters. Map-based cloning studies revealed that CTL1 mutations alter the ion profile of Arabidopsis thaliana. We found that the phenotypes associated with these mutations are caused by a combination of PD defects and ion transporter misregulation. We also established that CTL1 is involved in regulating vesicle trafficking and is thus required for the trafficking of proteins essential for ion transport and PD development. Characterizing choline transporter-like 1 (CTL1) as a new regulator of protein sorting may enable researchers to understand not only ion homeostasis in plants but also vesicle trafficking in general.
Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/metabolismo , Glicosídeo Hidrolases/fisiologia , Transporte de Íons/genética , Proteínas de Membrana Transportadoras/fisiologia , Adenosina Trifosfatases/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Transporte Biológico , Proteínas de Transporte de Cátions/metabolismo , Clonagem Molecular , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/metabolismo , Homeostase , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Mutação , Transporte Proteico , Simportadores/metabolismoRESUMO
Arabidopsis thaliana high-affinity potassium transporter 1 (AtHKT1) limits the root-to-shoot sodium transportation and is believed to be essential for salt tolerance in A. thaliana. Nevertheless, natural accessions with 'weak allele' of AtHKT1, e.g. Tsu-1, are mainly distributed in saline areas and are more tolerant to salinity. These findings challenge the role of AtHKT1 in salt tolerance and call into question the involvement of AtHKT1 in salinity adaptation in A. thaliana. Here, we report that AtHKT1 indeed drives natural variation in the salt tolerance of A. thaliana and the coastal AtHKT1, so-called weak allele, is actually hyper-functional in reducing flowers sodium content upon salt stress. Our data showed that AtHKT1 positively contributes to saline adaptation in a linear manner. Forward and reverse genetics analysis established that the single AtHKT1 locus is responsible for the variation in the salinity adaptation between Col-0 and Tsu-1. Reciprocal grafting experiments revealed that shoot AtHKT1 determines the salt tolerance of Tsu-1, whereas root AtHKT1 primarily drives the salt tolerance of Col-0. Furthermore, evidence indicated that Tsu-1 AtHKT1 is highly expressed in stems and is more effective compared to Col-0 AtHKT1 at limiting sodium flow to the flowers. Such efficient retrieval of sodium to the reproductive organ endows Tsu-1 with stronger fertility compared to Col-0 upon salt stress, thus improving Tsu-1 adaptation to a coastal environment. To conclude, our data not only confirm the role of AtHKT1 in saline adaptation, but also sheds light on our understanding of the salt tolerance mechanisms in plants.
Assuntos
Adaptação Fisiológica/genética , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Proteínas de Transporte de Cátions/genética , Flores/genética , Tolerância ao Sal/genética , Sódio/metabolismo , Simportadores/genética , Alelos , Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Salinidade , Cloreto de Sódio/metabolismoRESUMO
The removal of zinc ions (Zn(II)) in water and the separation of zinc isotopes were fully investigated in this study. Imidodiacetic acid (IDA) type adsorbent (named PSGI) based on polystyrene spheres (PS) was synthesized by simultaneous irradiation grafting. By adsorption method, the removal of Zn(II) from water by the chelating adsorbent was studied in batch experiments. Under optimized condition, PSGI showed the removal efficiency of more than 98 % for Zn(II) and the adsorption capacity of 70.1 mg/g. Langmuir isothermal and pseudo-second-order kinetic model fitted the experimental results better, indicating that the adsorption is dominated by chemical adsorption. The spent adsorbent (PSGI-Zn) was used for further zinc isotope separation by displacement chromatography using EDTA-NH4 solution as eluent. Due to the mass effect of isotopes, 70Zn was found to preferentially fractionated into the front-end effluents with the highest front enrichment values of 70Zn/64Zn. By extending the migration distance to 20 m, we obtained the best isotope enrichment with the front maximum enrichment values as 1.0949, 1.0739 and separation coefficient values as 1.977 × 10-3, 8.33 × 10-3 corresponding to the isotope pairs 66Zn/64Zn, 68Zn/64Zn.