Silencing of OsCV (chloroplast vesiculation) maintained photorespiration and N assimilation in rice plants grown under elevated CO2

Abstract High CO 2 concentrations stimulate net photosynthesis by increasing CO 2 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. Because high atmospheric CO 2 conditions diminished photorespiration, we tested whether CV silencing might be a viable strategy to improve the effects of high CO 2 on grain yield and N assimilation in rice. Under elevated CO 2 , OsCV expression was induced, and OsCV was targeted to peroxisomes where 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 H 2 O 2 content in wild‐type plants under elevated CO 2 . At elevated CO 2 , CV ‐silenced rice plants maintained peroxisome proliferation and photorespiration and displayed higher N assimilation than wild‐type plants. This was supported by higher activity of enzymes involved in NO 3 − and NH 4 + 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.