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Visible foliar injury and infrared imaging show that daylength affects short-term recovery after ozone stress in Trifolium subterraneum.

Vollsnes AV, Eriksen AB, Otterholt E, Kvaal K, Oxaal U, Futsaether CM - J. Exp. Bot. (2009)

Bottom Line: Multivariate statistical analyses showed that the leaves of ozone-exposed long-day-treated plants were also warmer with more homogeneous temperature distributions than exposed short day and control plants, suggesting reduced transpiration.Ozone did not affect the leaf temperature of short-day-treated plants.Thus, the twilight summer nights at high latitudes may have a negative effect on repair and defence processes activated after ozone exposure, thereby enhancing sensitivity.

View Article: PubMed Central - PubMed

Affiliation: Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, As, Norway.

ABSTRACT
Tropospheric ozone is a major air pollutant affecting plants worldwide. Plants in northern regions can display more ozone injury than plants at lower latitudes despite lower ozone levels. Larger ozone influx and shorter nights have been suggested as possible causes. However, the effects of the dim light present during northern summer nights have not been investigated. Young Trifolium subterraneum plants kept in environmentally controlled growth rooms under long day (10 h bright light, 14 h dim light) or short day (10 h bright light, 14 h darkness) conditions were exposed to 6 h of 70 ppb ozone during daytime for three consecutive days. Leaves were visually inspected and imaged in vivo using thermal imaging before and after the daily exposure. In long-day-treated plants, visible foliar injury within 1 week after exposure was more severe. Multivariate statistical analyses showed that the leaves of ozone-exposed long-day-treated plants were also warmer with more homogeneous temperature distributions than exposed short day and control plants, suggesting reduced transpiration. Temperature disruptions were not restricted to areas displaying visible damage and occurred even in leaves with only slight visible injury. Ozone did not affect the leaf temperature of short-day-treated plants. As all factors influencing ozone influx were the same for long- and short-day-treated plants, only the dim nocturnal light could account for the different ozone sensitivities. Thus, the twilight summer nights at high latitudes may have a negative effect on repair and defence processes activated after ozone exposure, thereby enhancing sensitivity.

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Related in: MedlinePlus

(A) PCA score plot highlighting the scores of individual leaves of short-day and long-day-treated plants the morning (32 d after sowing) after the first ozone exposure day and the first night with either SD or LD conditions. (B) Mean PCA scores for each treatment group on the evenings after ozone exposure and the following mornings. Open symbols, controls; filled symbols, ozone exposed. Circles and solid lines, short day; squares and dashed lines, long day.
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fig5: (A) PCA score plot highlighting the scores of individual leaves of short-day and long-day-treated plants the morning (32 d after sowing) after the first ozone exposure day and the first night with either SD or LD conditions. (B) Mean PCA scores for each treatment group on the evenings after ozone exposure and the following mornings. Open symbols, controls; filled symbols, ozone exposed. Circles and solid lines, short day; squares and dashed lines, long day.

Mentions: Figure 5A shows the PCA score plot for SD- and LD-treated plants the morning after the first ozone exposure and the first night. Leaf temperature distributions of control and exposed SD-treated plants were clustered around the origin, generally overlapping. LD-treated plants, however, showed very clear differences between leaf temperature distributions of ozone-exposed and control plants. The exposed and control distributions had separated into two distinct groups along PC1. The exposed distributions had more negative PC1 scores, indicating, by comparing with Fig. 4, that exposed leaves were warmer with more uniform leaf temperatures.


Visible foliar injury and infrared imaging show that daylength affects short-term recovery after ozone stress in Trifolium subterraneum.

Vollsnes AV, Eriksen AB, Otterholt E, Kvaal K, Oxaal U, Futsaether CM - J. Exp. Bot. (2009)

(A) PCA score plot highlighting the scores of individual leaves of short-day and long-day-treated plants the morning (32 d after sowing) after the first ozone exposure day and the first night with either SD or LD conditions. (B) Mean PCA scores for each treatment group on the evenings after ozone exposure and the following mornings. Open symbols, controls; filled symbols, ozone exposed. Circles and solid lines, short day; squares and dashed lines, long day.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2736887&req=5

fig5: (A) PCA score plot highlighting the scores of individual leaves of short-day and long-day-treated plants the morning (32 d after sowing) after the first ozone exposure day and the first night with either SD or LD conditions. (B) Mean PCA scores for each treatment group on the evenings after ozone exposure and the following mornings. Open symbols, controls; filled symbols, ozone exposed. Circles and solid lines, short day; squares and dashed lines, long day.
Mentions: Figure 5A shows the PCA score plot for SD- and LD-treated plants the morning after the first ozone exposure and the first night. Leaf temperature distributions of control and exposed SD-treated plants were clustered around the origin, generally overlapping. LD-treated plants, however, showed very clear differences between leaf temperature distributions of ozone-exposed and control plants. The exposed and control distributions had separated into two distinct groups along PC1. The exposed distributions had more negative PC1 scores, indicating, by comparing with Fig. 4, that exposed leaves were warmer with more uniform leaf temperatures.

Bottom Line: Multivariate statistical analyses showed that the leaves of ozone-exposed long-day-treated plants were also warmer with more homogeneous temperature distributions than exposed short day and control plants, suggesting reduced transpiration.Ozone did not affect the leaf temperature of short-day-treated plants.Thus, the twilight summer nights at high latitudes may have a negative effect on repair and defence processes activated after ozone exposure, thereby enhancing sensitivity.

View Article: PubMed Central - PubMed

Affiliation: Department of Mathematical Sciences and Technology, Norwegian University of Life Sciences, As, Norway.

ABSTRACT
Tropospheric ozone is a major air pollutant affecting plants worldwide. Plants in northern regions can display more ozone injury than plants at lower latitudes despite lower ozone levels. Larger ozone influx and shorter nights have been suggested as possible causes. However, the effects of the dim light present during northern summer nights have not been investigated. Young Trifolium subterraneum plants kept in environmentally controlled growth rooms under long day (10 h bright light, 14 h dim light) or short day (10 h bright light, 14 h darkness) conditions were exposed to 6 h of 70 ppb ozone during daytime for three consecutive days. Leaves were visually inspected and imaged in vivo using thermal imaging before and after the daily exposure. In long-day-treated plants, visible foliar injury within 1 week after exposure was more severe. Multivariate statistical analyses showed that the leaves of ozone-exposed long-day-treated plants were also warmer with more homogeneous temperature distributions than exposed short day and control plants, suggesting reduced transpiration. Temperature disruptions were not restricted to areas displaying visible damage and occurred even in leaves with only slight visible injury. Ozone did not affect the leaf temperature of short-day-treated plants. As all factors influencing ozone influx were the same for long- and short-day-treated plants, only the dim nocturnal light could account for the different ozone sensitivities. Thus, the twilight summer nights at high latitudes may have a negative effect on repair and defence processes activated after ozone exposure, thereby enhancing sensitivity.

Show MeSH
Related in: MedlinePlus