Enzyme of the plastid non-mevalonate pathway for isoprenoid biosynthesis that catalyzes the NADP-dependent rearrangement and reduction of 1-deoxy-D-xylulose-5-phosphate (DXP) to 2-C-methyl-D-erythritol 4-phosphate (MEP). Required for chloroplast development (By similarity). 2-C-methyl-D-erythritol 4-phosphate + NADP(+) = 1-deoxy-D-xylulose 5-phosphate + H(+) + NADPH Isoprenoid biosynthesis; isopentenyl diphosphate biosynthesis via DXP pathway; isopentenyl diphosphate from 1-deoxy-D-xylulose 5-phosphate: step 1/6. By the mycorrhizal fungus G.intraradices colonization in roots. Belongs to the DXR family.