Differential Accumulation of Dimethylallyl Diphosphate in Leaves and Needles of Isoprene- and Methylbutenol-Emitting and Nonemitting Species1
AUTOR(ES)
Rosenstiel, Todd N.
FONTE
American Society of Plant Physiologists
RESUMO
The biosynthesis and emission of volatile plant terpenoids, such as isoprene and methylbutenol (MBO), depend on the chloroplastic production of dimethylallyl diphosphate (DMAPP). To date, it has been difficult to study the relationship of cellular DMAPP levels to emission of these volatiles because of the lack of a sensitive assay for DMAPP in plant tissues. Using a recent DMAPP assay developed in our laboratories, we report that species with the highest potential for isoprene and MBO production also exhibit elevated light-dependent DMAPP production, ranging from 110% to 1,063%. Even species that do not produce significant amounts of volatile terpenoids, however, exhibit some potential for light-dependent production of DMAPP. We used a nonaqueous fractionation technique to determine the intracellular distribution of DMAPP in isoprene-emitting cottonwood (Populus deltoides) leaves; approximately 65% to 70% of the DMAPP recovered at midday occurred in the chloroplasts, indicating that most of the light-dependent production of DMAPP was chloroplastic in origin. The midday concentration of chloroplastic DMAPP in cottonwood leaves is estimated to be 0.13 to 3.0 mm, which is consistent with the relatively high Kms that have been reported for isoprene synthases (0.5–8 mm). The results provide support for the hypothesis that the light dependence of isoprene and MBO emissions is in part due to controls over DMAPP production.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=166521Documentos Relacionados
- Isoprene Increases Thermotolerance of Isoprene-Emitting Species.
- Thermotolerance of Leaf Discs from Four Isoprene-Emitting Species Is Not Enhanced by Exposure to Exogenous Isoprene1
- Crystal structure of isopentenyl diphosphate:dimethylallyl diphosphate isomerase
- Adenosine Diphosphate-Glucose Pyrophosphorylase Control of Starch Accumulation in Rust-infected Wheat Leaves 1
- 13C Labeling Reveals Chloroplastic and Extrachloroplastic Pools of Dimethylallyl Pyrophosphate and Their Contribution to Isoprene Formation1