Nuclear genome-encoded A/U-rich RNA-binding protein involved in the biogenesis of photosystem I (PSI) and II (PSII). Required for the light-controlled accumulation of PSI and PSII during early plant development (PubMed:17139246). Does not seem to be required for the translation of mRNAs of the PSI subunits (PubMed:25725436). Induced by salt stress. Albino phenotype and seedling growth arrest at 2 to 4 leaves.