1-Deoxy-D-xylulose 5-phosphate reductoisomerase and plastid isoprenoid biosynthesis during tomato fruit ripening

Rodriguez-Concepcion, M Ahumada, I Diez-Juez, E Sauret-Gueto, S Lois, LM Gallego, F Carretero-Paulet, L Campos, N Boronat, A

M. Rodriguez-concepcion et al., 1-Deoxy-D-xylulose 5-phosphate reductoisomerase and plastid isoprenoid biosynthesis during tomato fruit ripening, PLANT J, 27(3), 2001, pp. 213-222

38

INGLESE

Article

Plant Sciences","Animal & Plant Sciences

PLANT JOURNAL

0960-7412 → ACNP

27

3

2001

213 - 222

ISI

0960-7412(200108)27:3<213:15RAPI>2.0.ZU;2-J

The recently discovered 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway f or the biosynthesis of plastid isoprenoids (including carotenoids) is not f ully elucidated yet despite its central importance for plant life. It is kn own, however, that the first reaction completely specific to the pathway is the conversion of 1-deoxy-d-xylulose 5-phosphate (DXP) into MEP by the enz yme DXP reductoisomerase (DXR). We have identified a tomato cDNA encoding a protein with homology to DXR and in vivo activity, and show that the level s of the corresponding DXR mRNA and encoded protein in fruit tissues are si milar before and during the massive accumulation of carotenoids characteris tic of fruit ripening. The results are consistent with a non-limiting role of DXR, and support previous work proposing DXP synthase (DXS) as the first regulatory enzyme for plastid isoprenoid biosynthesis in tomato fruit. Inh ibition of DXR activity by fosmidomycin showed that plastid isoprenoid bios ynthesis is required for tomato fruit carotenogenesis but not for other rip ening processes. In addition, dormancy was reduced in seeds from fosmidomyc in-treated fruit but not in seeds from the tomato yellow ripe mutant (defec tive in phytoene synthase-1, PSY1), suggesting that the isoform PSY2 might channel the production of carotenoids for abscisic acid biosynthesis. Furth ermore, the complete arrest of tomato seedling development using fosmidomyc in confirms a key role of the MEP pathway in plant development.