Bibliogr. W artykule Agnieszka Banaś podpisana Agnieszka K. Banaś. Ewa Kowalska podpisana Ewa B. Kowalska

Many proteins belonging into cryptochrome/photolyase family play important roles in regulating plant function, acting as either blue light photoreceptors or as enzymes responsible for repair of pyrimidine dimers produced under UV. The members of plant-specific photolyase/blue-light receptor 2 (PPL/PHR2) subclade of this family, are almost completely uncharacterized. Here, we focused on the role of protein encoded by Arabidopsis At2g47590 gene. Mutants in this gene have albino cotyledons, pale green true leaves and drastically delayed development. Based on this features we named At2g47590 gene: GERALT (GERMINATION ALBINO TRANSIENT). Using different approach including analysis of plant phenotypes, chloroplast sizes and architecture, transcriptomes, photosynthetic pigments, maximum PSII quantum yield (FV/FM) we show that the proper plant functioning is the effect of co-operation of GERALT-dependent and -independent pathways with the role of the former diminishing with plant age. Lower levels of transcripts dependent on plastid encoded polymerase and higher levels of these dependent on nuclear encoded polymerase, smaller chloroplasts with large grana stacks and very weakly developed stromal thylakoids, lower levels of photosynthetic pigments with higher chlorophyll a/b ratio, are among characteristic features of geralt plants. We believe that these results will encourage scientific community to study PPL/PHR2 proteins.