Alternative Carbon Sources for Isoprene Emission
Isoprene and other plastidial isoprenoids are produced primarily from recently assimilated photosynthates via the 2-C-methyl-D-erythritol 4-phosphate (MEP) pathway. However, when environmental conditions limit photosynthesis, a fraction of carbon for MEP pathway can come from extrachloroplastic sources. The flow of extrachloroplastic carbon depends on the species and on leaf developmental and environmental conditions. The exchange of common phos- phorylated intermediates between the MEP pathway and other metabolic path- ways can occur via plastidic phosphate translocators. C1 and C2 carbon intermediates can contribute to chloroplastic metabolism, including photosyn- thesis and isoprenoid synthesis. Integration of these metabolic processes provide an example of metabolic flexibility, and results in the synthesis of primary metabolites for plant growth and secondary metabolites for plant defense, allowing effective use of environmental resources under multiple stresses.
Vinícius Fernandes de Souza, Ülo Niinemets, Bahtijor Rasulov, Claudia E. Vickers, Sergio Duvoisin Júnior, Wagner L. Araújo, and José Francisco de Carvalho Gonçalves