Silencing of OsCV (CHLOROPLAST VESICULATION) Maintained Photorespiration and N-assimilation in Rice Plants Grown under Elevated CO2.
High CO2 concentrations stimulate net photosynthesis by increasing CO2 substrate availability for Rubisco, simultaneously suppressing photorespiration. Previously, we reported that silencing the CHLOROPLAST VESICULATION (CV) gene in rice increased source fitness, through the maintenance of chloroplast stability and the expression of photorespiration-associated genes. Since high atmospheric CO2 conditions diminished photorespiration, we tested whether CV-silencing might be a viable strategy to improve the effects of high CO2 on grain yield and N-assimilation in rice. Under elevated CO2 , OsCV expression was induced and OsCV was targeted to peroxisomes were it facilitated the removal of OsPEX11-1 from the peroxisome and delivered it to the vacuole for degradation. This process correlated well with the reduction in the number of peroxisomes, the decreased catalase activity and the increased H2 O2 content in WT plants under elevated CO2 . At elevated CO2 , CV-silenced rice plants maintained peroxisome proliferation, photorespiration and displayed higher N assimilation than WT plants. This was supported by higher activity of enzymes involved in NO3 - and NH4 + assimilation and higher total and seed protein contents. Co-immunoprecipitation of OsCV-interacting proteins suggested that, similar to its role in chloroplast protein turnover, OsCV acted as a scaffold, binding peroxisomal proteins. This article is protected by copyright. All rights reserved.