Essential protein required during embryogenesis (PubMed:24097264). Exhibits holdase chaperone activity involved in the stabilization of NADPH:protochlorophyllide oxidoreductase (POR) proteins against photooxidative stress during POR proteins import into chloroplasts. Required for chloroplast biogenesis and development (PubMed:24151298, PubMed:25901327). When expressed in yeast, triggers mitochondria-mediated cell death associated with the loss of mitochondrial membrane potential (PubMed:16192270). Interacts with PORB in chloroplast (PubMed:24151298). Interacts with PORA during plastid import (PubMed:25901327). Targeted to mitochondrion when expressed in yeast. Expressed ubiquitously with higher levels in young leaves, flowers, and the root elongation zone. Low levels in the globular stage, but accumulates during early heart stage of embryogenesis and remains expressed during all later embryogenesis stages. Reduced chloroplast biogenesis and chlorophyll synthesis associated with less POR protein accumulation. Photobleaching and growth inhibition of plants under light conditions. In dark-grown plants, reduced POR accumulation in etioplasts and impaired formation of prolamellar bodies, subsequently affecting chloroplast biogenesis upon illumination (PubMed:24151298). Embryo lethal with arrested embryogenesis at the globular stage (PubMed:24097264). Belongs to the chaperone-like protein of POR1 protein family.