Regulation of carotenoid synthesis and accumulation in plants

The amounts and identities of the various carotenoids in the photosynthetic membranes of green plants are relatively well conserved

Francis X. Cunningham

2007

Scholarcy highlights

  • The amounts and identities of the various carotenoids in the photosynthetic membranes of green plants are relatively well conserved
  • The biosynthesis and accumulation of these carotenoids in developing chloroplasts proceed in concert with the assembly of the light-harvesting antennae and reaction centers with which these pigments are in large part associated
  • Genetic modifications that reduce or prevent synthesis of one or more of these carotenoids may be compensated by increases in others so that the total carotenoid content in the photosynthetic membranes is not much affected
  • Such observations make clear that robust feedback mechanisms exert control over carotenoid synthesis and accumulation in plant chloroplasts
  • The five carbon building blocks that serve as precursors for the synthesis of carotenoids and other isoprenoid compounds, isopentenyl diphosphate and dimethylallyl diphosphate, are produced in two different compartments and by two different pathways in plant cells
  • Is the supply of substrates a limiting factor in carotenoid synthesis in plants? If so, which enzymatic reactions of the MEP pathway are most restrictive of pathway flux? Perhaps one of the first indications that substrate supply might limit plastid isoprenoid synthesis came from analyses of transgenic tomato plants that had been engineered to overexpress phytoene synthase, the initial enzyme of the carotenoid pathway, from a constitutive promoter
  • Control of pathway flux may be mediated, in part, by changes in the expression of genes encoding enzymes of the pathway, those for phytoene synthase and the cyclases, and by the availability of substrates produced via the MEP pathway

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