AMY E. WIBERLEY

University of Wisconsin–Stevens Point

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Thomas D. Sharkey

Michigan State University

AUTUMN R. DONOHUE

University of Wisconsin–Madison

Tanya G. Falbel

University of Wisconsin–Madison

MAIKEN M. WESTPHAL

University of Wisconsin–Madison

AUTUMN R. LINSKEY

University of Wisconsin–Madison

Francesco Loreto

University of Naples Federico II

Deming Gong

State Key Laboratory of Food Science and Technology

Donna E. Fernandez

University of Wisconsin–Madison

David F. Karnosky

Michigan Technological University

Carlo Calfapietra

National Research Council

Cooperative Institutions

University of Wisconsin–Madison

University of Auckland

National Research Council

University of Palermo

National Academies of Sciences, Engineering, and Medicine

University of Colorado Boulder

University of Naples Federico II

Institute for Sustainable Plant Protection

Ospedale generale di zona San Camillo Treviso

Consorzio Roma Ricerche

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Isoprene Emission from Plants: Why and How

Annals of Botany (2007)

Thomas D. Sharkey AMY E. WIBERLEY AUTUMN R. DONOHUE

Some, but not all, plants emit isoprene. Emission of the related monoterpenes is more universal among plants, but the amount of isoprene emitted from plants dominates the biosphere-atmosphere hydrocarbon exchange.

Isoprene

10.1093/aob/mcm240

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Citations (640)

Isoprene synthase expression and protein levels are reduced under elevated O₃ but not under elevated CO₂ (FACE) in field‐grown aspen trees

Plant Cell & Environment (2007)

Carlo Calfapietra AMY E. WIBERLEY Tanya G. Falbel AUTUMN R. LINSKEY Giuseppe Scarascia Mugnozza

ABSTRACT Emission of hydrocarbons by trees has a crucial role in the oxidizing potential of the atmosphere. In particular, isoprene oxidation leads to the formation of tropospheric ozone and other secondary pollutants. It is expected that changes in the composition of the atmosphere will influence the emission rate of isoprene, which may in turn feedback on the accumulation of pollutants and greenhouse gases. We investigated the isoprene synthase ( ISPS ) gene expression and the ISPS protein levels in aspen trees exposed to elevated ozone (O 3 ) and/or elevated carbon dioxide (CO 2 ) in field‐grown trees at the Aspen Free‐Air Carbon Dioxide Enrichment (FACE) experimental site. Elevated O 3 reduced ISPS mRNA and the amount of ISPS protein in aspen leaves, whereas elevated CO 2 had no significant effect. Aspen clones with different O 3 sensitivity showed different levels of inhibition under elevated O 3 conditions. The drop in ISPS protein levels induced a drop in the isoprene emission rate under elevated O 3 . However, the data indicated that other mechanisms also contributed to the observed strong inhibition of isoprene emission under elevated O 3 .

Isoprene

Oxidizing agent

Tropospheric ozone

10.1111/j.1365-3040.2007.01646.x

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Evolution of the Isoprene Biosynthetic Pathway in Kudzu

PLANT PHYSIOLOGY (2005)

Thomas D. Sharkey Sansun Yeh AMY E. WIBERLEY Tanya G. Falbel Deming Gong

Isoprene synthase converts dimethylallyl diphosphate, derived from the methylerythritol 4-phosphate (MEP) pathway, to isoprene. Isoprene is made by some plants in substantial amounts, which affects atmospheric chemistry, while other plants make no isoprene. As part of our long-term study of isoprene synthesis, the genetics of the isoprene biosynthetic pathway of the isoprene emitter, kudzu (Pueraria montana), was compared with similar genes in Arabidopsis (Arabidopsis thaliana), which does not make isoprene. The MEP pathway genes in kudzu were similar to the corresponding Arabidopsis genes. Isoprene synthase genes of kudzu and aspen (Populus tremuloides) were cloned to compare their divergence with the divergence seen in MEP pathway genes. Phylogenetic analysis of the terpene synthase gene family indicated that isoprene synthases are either within the monoterpene synthase clade or sister to it. In Arabidopsis, the gene most similar to isoprene synthase is a myrcene/ocimene (acyclic monoterpenes) synthase. Two phenylalanine residues found exclusively in isoprene synthases make the active site smaller than other terpene synthase enzymes, possibly conferring specificity for the five-carbon substrate rather than precursors of the larger isoprenoids. Expression of the kudzu isoprene synthase gene in Arabidopsis caused Arabidopsis to emit isoprene, indicating that whether or not a plant emits isoprene depends on whether or not it has a terpene synthase capable of using dimethylallyl diphosphate.

Isoprene

Kudzu

Terpene

10.1104/pp.104.054445

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Regulation of isoprene emission from poplar leaves throughout a day

Plant Cell & Environment (2009)

AMY E. WIBERLEY AUTUMN R. DONOHUE MAIKEN M. WESTPHAL Thomas D. Sharkey

Isoprene is a biogenic hydrocarbon that significantly affects tropospheric chemistry. Numerous plant species, including many trees, emit isoprene. Isoprene is synthesized by isoprene synthase (IspS), from dimethylallyl diphosphate (DMADP) made by the methylerythritol 4-phosphate (MEP) pathway. It has been demonstrated that in developing leaves, isoprene emission is regulated by transcriptional control of IspS, while in mature leaves subjected to changing growth temperature, regulation of emission is shared between IspS and DMADP supply from the MEP pathway. Isoprene emission also varies throughout a day, with circadian regulation implicated. This study investigated changes in isoprene emission capacity, and expression of IspS and the enzymes of the MEP pathway throughout several days, with Populus trichocarpa grown at different temperatures to induce different levels of isoprene emission. Isoprene emission capacity exhibited ultradian regulation, with a period of about 12 h; peak capacity was observed at 0300 and 1500 h daily. Several of the enzymes of the MEP pathway had previously been suggested to have regulatory roles in the production of other plastidic terpenoids, and transcript accumulation for these enzymes, combined with in silico promoter analyses, supported a regulatory role for deoxyxylulose 5-phosphate synthase (DXS) in particular.

Isoprene

10.1111/j.1365-3040.2009.01980.x

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Development of the capacity for isoprene emission in kudzu

Plant Cell & Environment (2005)

AMY E. WIBERLEY AUTUMN R. LINSKEY Tanya G. Falbel Thomas D. Sharkey

ABSTRACT Isoprene is a biogenic hydrocarbon that has significant effects on tropospheric chemistry. It is emitted by a number of plant species, including kudzu, a leguminous vine that grows profusely in the south‐eastern United States. This study investigated development of the capacity for isoprene emission in kudzu. Previous studies examined isoprene emission during leaf development, but a molecular explanation for the observed developmental delay in emission was lacking. This study found that kudzu leaves grown at a high temperature could emit isoprene at least a week before they were fully expanded and 1 d after becoming photosynthetically competent. When grown at low temperature, however, leaves did not emit isoprene until 1 week after they became fully expanded and 2 weeks after the onset of photosynthetic competence. Levels of mRNA and protein for isoprene synthase, which catalyses the final step in isoprene biosynthesis, were investigated; it was found that transcription and translation of this gene began at the same developmental stage as onset of emission in both growth conditions. Therefore, plant growth conditions, not leaf developmental stage, have primary control over expression of isoprene synthase and onset of kudzu isoprene emission. This finding may be useful in modelling early season isoprene emission rates.

Isoprene

Kudzu

10.1111/j.1365-3040.2005.01342.x

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Regulation of isoprene emission in Populus trichocarpa leaves subjected to changing growth temperature

Plant Cell & Environment (2007)

AMY E. WIBERLEY AUTUMN R. DONOHUE MARY E. MEIER MAIKEN M. WESTPHAL Thomas D. Sharkey

ABSTRACT The hydrocarbon isoprene is emitted in large quantities from numerous plant species, and has a substantial impact on atmospheric chemistry. Temperature affects isoprene emission at several levels: the temperature at which emission is measured, the temperature at which leaves develop, and the temperatures to which a mature leaf is exposed in the days prior to emission measurement. The molecular regulation of the response to the last of these factors was investigated in this study. When plants were grown at 20 °C and moved from 20 to 30 °C and back, or grown at 30 °C and moved from 30 to 20 °C and back, their isoprene emission peaked within 3 h of the move and stabilized over the following 3 d. Trees that developed at 20 °C and experienced 30 °C episodes had higher isoprene emission capacities than did leaves grown exclusively at 20 °C, even 2 weeks after the last 30 °C episode. The levels and extractable activities of isoprene synthase protein, which catalyses the synthesis of isoprene, and those of dimethylallyl diphosphate (DMADP), its substrate, alone could not explain observed variations in isoprene emission. Therefore, we conclude that control of isoprene emission in mature leaves is shared between isoprene synthase protein and DMADP supply.

Isoprene

Populus trichocarpa

Salicaceae

10.1111/j.1365-3040.2007.01758.x

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Citations (57)