Promotes the splicing of group II introns in chloroplasts. Required for the splicing of intron 2 of plastid ycf3 transcripts, a factor required for the assembly of photosystem I (PSI). Involved in the splicing of atpF, ndhA, petB and rps16 chloroplastic transcripts. Required for the assembly of PSI. Chlorophyll deficiency and seedling lethality when grown under normal light or low light. Belongs to the PPR family. P subfamily.