Editing Isoprene (section)

===Plants===
Isoprene is made through the [[Non-mevalonate pathway|methyl-erythritol 4-phosphate pathway]] (MEP pathway, also called the non-[[mevalonate pathway]]) in the [[chloroplast]]s of plants. One of the two end-products of MEP pathway, [[dimethylallyl pyrophosphate]] (DMAPP), is cleaved by the enzyme [[isoprene synthase]] to form isoprene and diphosphate. Therefore, inhibitors that block the MEP pathway, such as [[fosmidomycin]], also block isoprene formation. Isoprene emission increases dramatically with temperature and maximizes at around 40&nbsp;°C. This has led to the hypothesis that isoprene may protect plants against heat stress (thermotolerance hypothesis, see below). Emission of isoprene is also observed in some bacteria and this is thought to come from non-enzymatic degradations from DMAPP. Global emission of isoprene by plants is estimated at 350 million tons per year.<ref>{{Cite web |last= |first= |title=Isoprene emissions version 2021 |url=https://emissions.aeronomie.be/index.php/bottom-up/isoprenev2021 |access-date=2022-09-26 |website=emissions.aeronomie.be |language=en}}</ref>

====Regulation====
Isoprene emission in plants is controlled both by the availability of the substrate (DMAPP) and by [[enzyme]] (isoprene synthase) activity. In particular, light, CO<sub>2</sub> and O<sub>2</sub> dependencies of isoprene emission are controlled by substrate availability, whereas temperature dependency of isoprene emission is regulated both by substrate level and enzyme activity.