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
2O
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.
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