Involved in the synthesis of tocopherols (vitamin E), which presumably protect photosynthetic complexes from oxidative stress (Probable). Catalyzes the conversion of 2,3-dimethyl-5-phytyl-1,4-hydroquinone (DMPQ) to gamma-tocopherol (PubMed:12913173). gamma-tocopherol = 2,3-dimethyl-6-phytylbenzene-1,4-diol Cofactor biosynthesis; tocopherol biosynthesis. Present in all green tissues, both in bundle sheath and in mesophyll cells.