Plant NADPH-dependent thioredoxin reductases are crucial for the metabolism of sink leaves and plant acclimation to elevated CO2

Plants contain three NADPH-thioredoxin reductases (NTR) located in the cytosol/mitochondria (NTRA/B) and the plastid (NTRC) with important metabolic functions. However, mutants deficient in all NTRs remained to be investigated. Here, we generated and characterised the triple Arabidopsis ntrabc mutant alongside with ntrc single and ntrab double mutants under different environmental conditions. Both ntrc and ntrabc mutants showed reduced growth and substantial metabolic alterations, especially in sink leaves and under high CO₂ (HC), as compared to the wild type. However, ntrabc showed higher effective quantum yield of PSII under both constant and fluctuating light conditions, altered redox states of NADH/NAD⁺ and glutathione (GSH/GSSG) and lower potential quantum yield of PSII in sink leaves in ambient but not high CO₂ concentrations, as compared to ntrc, suggesting a functional interaction between chloroplastic and extra-chloroplastic NTRs in photosynthesis regulation depending on leaf development and environmental conditions. Our results unveil a previously unknown role of the NTR system in regulating sink leaf metabolism and plant acclimation to HC, while it is not affecting full plant development, indicating that the lack of the NTR system can be compensated, at least to some extent, by other redox mechanisms.

Comparing Bacillus Calmette-Guérin (BCG) strains in convalescent COVID-19 patients

Aim: We previously published results of the BATTLE trial, showing that patients recently infected with SARS-CoV-2 can benefit from receiving Bacillus Calmette-Guérin (BCG) with minimal adverse effects. The study incorporated two strains of this vaccine. In this study, patient outcomes were compared based on the strain of BCG because different strains have been shown to have different immunogenicity. Methods: BATTLE was a double-blind controlled trial of COVID-19 convalescent patients; symptom progression, injection-site lesion characteristics and adverse effects were compared between recipients of placebo, Russian BCG strain or Brazilian BCG strains. Results: There was no statistically significant difference between the two BCG strains in terms of symptom progression, lesion-size or type. Conclusion: The two strains have similar clinical outcomes in COVID-19 convalescent patients.