title: De novo post-illumination monoterpene burst in Quercus ilex (holm oak).
abstract: Explicit proof for de novo origin of a rare post-illumination monoterpene burst and its consistency under low O2, shows interaction of photorespiration, photosynthesis, and isoprenoid biosynthesis during light-dark transitions. Quercus ilex L (holm oak) constitutively emits foliar monoterpenes in an isoprene-like fashion via the methyl erythritol phosphate (MEP) pathway located in chloroplasts. Isoprene-emitting plants are known to exhibit post-illumination isoprene burst, a transient emission of isoprene in darkness. An analogous post-illumination monoterpene burst (PiMB) had remained elusive and is reported here for the first time in Q. ilex. Using13CO2labelling, we show that PiMB is made from freshly fixed carbon. PiMB is rare at ambient (20%) O2, absent at high (50%) O2, and becomes consistent in leaves exposed to low (2%) O2. PiMB is stronger and occurs earlier at higher temperatures. We also show that primary and secondary post-illumination CO2bursts (PiCO2B) are sensitive to O2in Q. ilex. The primary photorespiratory PiCO2B is absent under both ambient and low O2, but is induced under high (>50%) O2, while the secondary PiCO2B (of unknown origin) is absent under ambient, but present at low and high O2. We propose that post-illumination recycling of photorespired CO2competes with the MEP pathway for photosynthetic carbon and energy, making PiMB rare under ambient O2and absent at high O2. PiMB becomes consistent when photorespiration is suppressed in Q. ilex.
authors.affiliation: Institute of Ecosystem Studies, National Research Council of Italy, via Madonna del Piano 10, 50019, Sesto Fiorentino (FI), Italy. srikantadani@yahoo.co.uk.|Department of Biological Sciences, Macquarie University, North Ryde, Sydney, NSW 2109, Australia. srikantadani@yahoo.co.uk.|School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala, 695016, India. srikantadani@yahoo.co.uk.
authors.forename: K G
authors.initials: KG
authors.lastname: Srikanta Dani
authors.affiliation: Trees and Timber Institute, National Research Council of Italy, via Madonna del Piano 10, 50019, Sesto Fiorentino (FI), Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Marino
authors.affiliation: Department of Environmental Science and Agricultural Production, University of Florence, Viale delle Idee 30, 50019, Sesto Fiorentino (FI), Italy.
authors.forename: Cosimo
authors.initials: C
authors.lastname: Taiti
authors.affiliation: Department of Environmental Science and Agricultural Production, University of Florence, Viale delle Idee 30, 50019, Sesto Fiorentino (FI), Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Mancuso
authors.affiliation: Department of Biological Sciences, Macquarie University, North Ryde, Sydney, NSW 2109, Australia.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Atwell
authors.affiliation: Department of Biology, Agriculture and Food Sciences, National Research Council of Italy, Piazzale Aldo Moro 7, 00185, Rome, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Loreto
authors.affiliation: Trees and Timber Institute, National Research Council of Italy, via Madonna del Piano 10, 50019, Sesto Fiorentino (FI), Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Centritto
mesh_terms: D002070:Butadienes / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D003624:Darkness; D045782:Hemiterpenes / Q000378:metabolism; D008027:Light; D039821:Monoterpenes / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010420:Pentanes / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D029963:Quercus / Q000378:metabolism*
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D039821:Monoterpenes; D010420:Pentanes; C005059:isoprene; D002245:Carbon Dioxide; D010100:Oxygen
keywords: 13CO2 labelling; Light–dark transition; MEP pathway; Monoterpene emission; Photorespiratory CO2 recycling; Photosynthesis; Post-illumination bursts