Physiological responses of Quercus ilex Leaves to Water Stress and Acute Ozone Exposure Under Controlled Conditions

TitlePhysiological responses of Quercus ilex Leaves to Water Stress and Acute Ozone Exposure Under Controlled Conditions
Publication TypeJournal Article
Year of Publication2007
AuthorsVitale, M., Salvatori E., Loreto F., Fares S., & Manes F.
JournalWater, Air, and Soil Pollution
Volume189
Issue1-4
Pagination113 - 125
Date Published2007///
KeywordsGas exchange, Holm oak (Quercus ilex), lipoxygenase products, monoterpene emission, o3 flux, photosynthesis, Stomatal conductance
Abstract

The combined effect of water stress and ozone (O3) on stomatal O3 flux, damage to photosynthesis, and detoxification by biogenic volatile organic compounds (BVOC) in Quercus ilex leaves was studied. A 4-weeks O3 exposure (250 ppb, 4 h per day) caused a reduction of photosynthesis and stomatal conductance, which was fully recovered 1 week after the end of the treatment, in well-watered and water-stressed plants. Measurements of stomatal O3 flux revealed a low stomatal flux of the pollutant, which became minimal after stomatal closure caused by water stress. An induction of volatile monoterpenes, important compounds in the O3 scavenging system in Q. ilex, and a burst of lipoxygenase compounds (LOX), which are released as gaseous by-products of membrane peroxidation, was observed after 2–3 weeks of O3 fumigation. However, these compounds were also released in control leaves that were exposed to ozone only briefly, to determine stomatal O3 flux. The low stomatal flux that occurred in water stress conditions helped avoiding permanent damage to Q. ilex leaves, although during the O3 treatment photosynthesis was severely limited by stomatal closure. In well-watered plants, O3 fumigation caused a noticeable increase of nocturnal stomatal conductance. If confirmed on adult plants under field conditions, this effect can imply larger flux of O3 at night and possible detrimental effects of O3 on leaf functions in plants exposed to high nocturnal O3 levels.

URLhttp://www.springerlink.com/index/10.1007/s11270-007-9560-4