Osmotic adjustments support growth of poplar cultured cells under high concentrations of carbohydrates

Silver nanoparticles enhance the mitigation of osmotic stress in Chenopodium quinoa microshoots grown under in vitro osmo-stressing conditions

Osmotic stress is one of the main destructive abiotic factors that hinder plant growth and development. In this research, the role of silver nanoparticles (Ag NPs) in mitigating the negative impact of osmotic stress on in vitro grown Chenopodium quinoa (Quinoa 6 Line; Q6) was investigated to determine whether Ag NPs were able to reduce the negative effects on the in vitro grown cultures of the Q6 line. The explants were subcultured onto a special osmostressing media containing sucrose, sorbitol, or mannitol at different levels (0.1, 0.2, 0.3, and 0.4 mol/L) to mimic the osmotic stressing environment for four weeks. Then, stress physiological responses of in vitro grown Q6 under the induced osmotic stress were investigated to determine the highest stress level that the microshoots could tolerate. Next, Ag NPs; 25, 50, and 75 mg/L were added to the medium that contained the highest stress level of the induced osmotic stress to determine if their addition improved the physiological performance of the Q6 microshoots under the most severe osmotic agent levels. The results revealed that 0.4 mol/L sucrose, 0.3 mol/L sorbitol, and 0.3 mol/L mannitol were the highest stress levels that the microshoots could tolerate. The addition of 75 mg/L Ag NPs to the previous highest stress levels resulted in a significant increase in the following: stem length (SL), leaves number (LN), fresh weight (FW), dry weight (DW), total chlorophyll, protein, calcium (Ca), and phosphorus (P) contents, while it caused a reduction in proline, sodium (Na) ions, and potassium (K) ions. These results indicate that the negative consequences of osmotic stress on Q6 quinoa microshoots could be mitigated by adding specific concentrations of Ag NPs to the culture medium.

Osmotic pressure induces translocation of aquaporin-8 by P38 and JNK MAPK signaling pathways in patients with functional constipation

BACKGROUND

Aquaporins (AQPs) maintain fluid homeostasis in the colon. The role of colonic AQPs in the pathophysiology of functional constipation (FC) remains largely unknown.

AIM

To explore variations in aquaporins and investigate their underlying mechanisms.

METHODS

Colonic biopsies were collected from patients with FC and healthy controls. The expression and localization of AQPs were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis, and immunofluorescence assays. Furthermore, osmotic pressure-induced cell model was used in vitro to investigate the potential relationship between AQP8 and osmotic pressure, and to reveal the underlying mechanisms.

RESULTS

Upregulation of AQP3 and AQP8, and downregulation of AQP1, AQP7, AQP9, AQP10, and AQP11 were observed in the patients with functional constipation. Furthermore, cellular translocation of AQP8 from the cytoplasm to the plasma membrane was observed in patients with FC. Mechanistically, the increase in osmotic pressure could activate the Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) signaling pathways, and subsequently promote the upregulation and translocation of AQP8.

CONCLUSION

Upregulation of AQP8 and AQP3, and translocation of AQP8 were observed in colon biopsies from patients with FC. The p38 and JNK MAPK signaling pathways are involved in the regulation of osmotic pressure-induced AQP8 variation.

Expression of the pyrroline-5-carboxylate reductase (P5CR) gene from the wild grapevine Vitis yeshanensis promotes drought resistance in transgenic Arabidopsis

Proline accumulation is one of the most common reactions in plants under drought stress. Pyrroline-5-carboxylate reductase (P5CR) is the final enzyme and plays an important role in proline biosynthesis. The Chinese wild grapevine Vitis yeshanensis J.X. Chen accession 'Yanshan-1' is highly resistant to drought, but the genetic and molecular mechanisms associated with this resistance have not been elucidated. Here, we cloned a VyP5CR gene (Genbank ID: MZ226960) from 'Yanshan-1', and evaluated its transcriptional response to drought, NaCl, cold, as well as exogenous ABA, MeJA and SA. Tissue specific analysis showed that VyP5CR could be expressed in various organs and was highly expressed in roots. To gain insight into the roles of VyP5CR, we overexpressed VyP5CR in Arabidopsis thaliana (Arabidopsis). Transgenic Arabidopsis plants expressing VyP5CR showed enhanced survival rate, smaller stomata in response to severe drought, as well as stronger root growth on a medium containing mannitol. Under drought stress, VyP5CR-OE plants showed reduced levels of MDA, H2O2 and O2-, and higher proline content, SOD and POD activity. In addition, VyP5CR-OE plants showed increased induction of the drought-related genes COR15A, COR47, DREB2A, KIN1, NCED3 and RD29A. Taken together, these experiments reveal that VyP5CR can promote the drought tolerance of transgenic Arabidopsis. Besides, an interacting protein with VyP5CR, VyCSN5B (COP9 signalosome complex subunit 5b), was screened out by yeast two-hybrid and verified by bimolecular fluorescence complementation assay.