Involved in one of the last steps of the biosynthesis of chlorophyll a. Catalyzes the esterification of chlorophillide a or b with a preference for geranylgeranyldiphosphate (GGPP) rather than for phytyldiphosphate (PhyPP). chlorophyllide a + H(+) + phytyl diphosphate = chlorophyll a + diphosphate Porphyrin-containing compound metabolism; chlorophyll biosynthesis. Low level in flower buds, flowers, stems, leaves, greening cotyledons and immature siliques, but not in mature siliques or seeds. Belongs to the UbiA prenyltransferase family. Chlorophyll synthase subfamily.