Ultraviolet-B Radiation and Photosynthesis

Teramura, Alan H.; Ziska, Lewis H.

doi:10.1007/0-306-48135-9_18

Cited by 40 publications

(46 citation statements)

References 121 publications

(137 reference statements)

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“…The UV spectrum at the top of the plants was measured with a scanning spectroradiometer (SR 991-PC, Macam Photometrics, Livingston, UK) and was the same as that previously described (Allen et al, 1997). Greenhouse and cabinet transmission of UV-A radiation, supplemented by the UV fluorescent lamps, ensured that UV-A exposure was maintained for photorepair and flavonoid biosynthesis (Teramura and Ziska, 1996). Plants were grown throughout their development without UV-B or with three different UV-B doses.…”

Section: Exposure To Different Uv-b Irradiance and Leaf Inversion Expmentioning

confidence: 99%

“…On exposure to increased levels of UV-B radiation, many plant species exhibit reductions in their net photosynthetic rate and productivity (Teramura and Ziska, 1996). High UV-B irradiance has been shown to inhibit photosynthesis in pea (Nogués and Baker, 1995), oilseed rape (Allen et al, 1997), soybean (Middleton and Teramura, 1993), rice (Ziska and Teramura, 1992), and algae (Lesser, 1996).…”

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Characterization of Stomatal Closure Caused by Ultraviolet-B Radiation

et al. 1999

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The effects of ultraviolet-B (UV-B) radiation on stomatal conductance (g s ) in pea (Pisum sativum L.), commelina (Commelina communis L.), and oilseed rape (Brassica napus L.) plants were investigated. Plants were grown in a greenhouse either with three different high ratios of UV-B to photosynthetically active radiation or with no UV-B radiation. On exposure to increased levels of UV-B radiation, many plant species exhibit reductions in their net photosynthetic rate and productivity (Teramura and Ziska, 1996). High UV-B irradiance has been shown to inhibit photosynthesis in pea (Nogués and Baker, 1995), oilseed rape (Allen et al., 1997), soybean (Middleton and Teramura, 1993), rice (Ziska and Teramura, 1992), and algae (Lesser, 1996). Such inhibition of photosynthetic competence primarily involves the loss of both Rubisco activity and content (Allen et al., 1997), but is also associated with the loss of activity of sedoheptulose 1,7-biphosphatase (Allen et al., 1998), and probably that of other Calvin cycle enzymes, and is sometimes associated with damage to PSII photochemistry (Nogués and Baker, 1995;Baker et al., 1997;Allen et al., 1998).It is not clear whether changes in stomatal function play a major role in the UV-B-induced inhibition of CO 2 assimilation. An increase in stomatal limitation observed in oilseed rape (Allen et al., 1997) and soybean (Middleton and Teramura, 1993), together with a reduction in the intercellular CO 2 concentration (c i ) in pea (Day and Vogelmann, 1995), suggests that there may be a direct UV-B effect on stomatal function. However, it is widely reported that any UV-B effects on stomata do not affect CO 2 assimilation (Murali and Teramura, 1986;Sullivan and Teramura, 1989;Teramura et al., 1991;Ziska and Teramura, 1992). Recent studies on pea leaves developed under high UV-B irradiance showed that there were no changes in any photosynthetic parameter measured: light-saturated net CO 2 assimilation rate (A sat ), maximum carboxylation velocity of Rubisco (V cmax ), maximum potential rate of electron transport contributing to RuBP regeneration (J max ), ratio of variable to maximal chlorophyll fluorescence yield (F v /F m ), and the relative quantum efficiency of PSII photochemistry ( PSII ) although there were reductions of adaxial stomatal conductance (g s ), but not abaxial g s (Nogués et al., 1998). The effects on adaxial g s were mediated by changes in aperture, as there was no reduction in stomatal density in these pea leaves (Nogués et al., 1998). This demonstrated direct effects of high UV-B on g s in the long term (days). In contrast, small (30%) increases in the natural dose had no measurable effects on the g s of pea plants grown in the field (Allen et al., 1999).The objective of this study was to further characterize the effect of UV-B radiation on g s . We studied the effect of growth under three different ratios of UV-B to PAR or with no UV-B radiation on adaxial and abaxial g s in leaves of pea (Pisum sativum). Only at the higher UV-B irradiances (Ͼ3ϫ maximum midsum...

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Section: Exposure To Different Uv-b Irradiance and Leaf Inversion Expmentioning

confidence: 99%

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confidence: 99%

Characterization of Stomatal Closure Caused by Ultraviolet-B Radiation

et al. 1999

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“…In leaves of tropical tree seedlings grown in simulated, differently sized tree-fall gaps, the level of UV screening substances was positively related to the radiation dose determined by the duration of daily sun exposure (Krause et al, 2001). However, when the protective mechanisms are overtaxed, detrimental effects of elevated UV-B radiation on photosynthesis do occur (for review, see Teramura and Ziska, 1996). In particular, photosystem (PS) II has been found to be UV-B-sensitive, whereas PSI appeared to be unaffected by UV-B.…”

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confidence: 99%

Sudden Exposure to Solar UV-B Radiation Reduces Net CO2 Uptake and Photosystem I Efficiency in Shade-Acclimated Tropical Tree Seedlings

et al. 2003

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Tree seedlings developing in the understory of the tropical forest have to endure short periods of high-light stress when tree-fall gaps are formed, and direct solar radiation, including substantial UV light, reaches the leaves. In experiments simulating the opening of a tree-fall gap, the response of photosynthesis in leaves of shade-acclimated seedlings (Anacardium excelsum, Virola surinamensis, and Calophyllum longifolium) to exposure to direct sunlight (for 20-50 min) was investigated in Panama (9°N). To assess the effects of solar UV-B radiation (280-320 nm), the sunlight was filtered through plastic films that selectively absorbed UV-B or transmitted the complete spectrum. The results document a strong inhibition of CO 2 assimilation by sun exposure. Light-limited and light-saturated rates of photosynthetic CO 2 uptake by the leaves were affected, which apparently occurred independently of a simultaneous inhibition of potential photosystem (PS) II efficiency. The ambient UV-B light substantially contributed to these effects. The photochemical capacity of PSI, measured as absorbance change at 810 nm in saturating far-red light, was not significantly affected by sun exposure of the seedlings. However, a decrease in the efficiency of P700 photooxidation by far-red light was observed, which was strongly promoted by solar UV-B radiation. The decrease in PSI efficiency may result from enhanced charge recombination in the reaction center, which might represent an incipient inactivation of PSI, but contributes to thermal dissipation of excessive light energy and thereby to photoprotection.The thinning of the stratospheric ozone layer and the resulting increase in solar UV-B radiation (280-320 nm) at the earth's surface have led to major research efforts in studying the effects of UV-B on photosynthetic organisms. Based on a survey of a large number of long-term field studies of vascular plants published between 1976between and 1999between , Searles et al. (2001 concluded that artificially elevated UV-B induced an increase in content of UV-B-absorbing compounds, but had little or no effect on morphological parameters and leaf photosynthesis as measured by means of gas exchange and chlorophyll (Chl) fluorescence. More recent studies also did not show effects of substantially elevated UV-B on photosynthetic performance of several plant species (Nogués and Baker, 2000;Lud et al., 2001; Bassman et al., 2002). It appears that in many cases, plants are capable of acclimating and, thereby, achieve efficient protection against increased UV-B levels (for review, see Allen et al., 1998). In leaves of tropical tree seedlings grown in simulated, differently sized tree-fall gaps, the level of UV screening substances was positively related to the radiation dose determined by the duration of daily sun exposure (Krause et al., 2001). However, when the protective mechanisms are overtaxed, detrimental effects of elevated UV-B radiation on photosynthesis do occur (for review, see Teramura and Ziska, 1996). In particular, photosy...

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“…In photosynthetic organisms, UV-B radiation exerts direct effects on photosynthetic light reactions and carbon reduction (Teramura and Ziska, 1996). Several protection and repair mechanisms have been elucidated, but little is known about how carotenoids alleviate UV-B stress exerted on the cell and on the photosynthesis apparatus.…”

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confidence: 99%

“…These radicals accumulate in the thylakoids and are responsible for peroxidation reactions that destroy various components of the photosynthesis apparatus (Malanga et al, 1997), among which are the D1 and D2 proteins of PSII, which are highly susceptible to peroxidative conditions (Greenberg et al, 1989;Jansen et al, 1996). Protection against UV-B can occur at different levels (for review, see Teramura and Ziska, 1996). Plants can accumulate UV-B-screening compounds such as flavonoids (Middleton and Teramura, 1993), the antioxidant system can inactivate oxygen radicals, or the effective replacement of damaged constituents can resist UV-B stress, as was shown for the D1 protein (Campbell et al, 1998).…”

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Protection of Photosynthesis against Ultraviolet-B Radiation by Carotenoids in Transformants of the CyanobacteriumSynechococcus PCC79421

et al. 1999

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The cyanobacterium Synechococcus PCC7942 was transformed with various carotenogenic genes, and the resulting transformants either accumulated higher amounts of ␤-carotene and zeaxanthin or showed a shift in the carotenoid pattern toward the formation of zeaxanthin. These transformants were exposed to ultraviolet-B (UV-B) radiation, and the degradation of phycobilins, the inactivation of photosynthetic oxygen evolution, and the activity of photosystem II were determined. In the genetically modified cells, the influence on destruction of phycobilins was negligible. However, protection of photosynthetic reactions against UV-B damage was observed and was dependent on the carotenoid concentrations in the different transformants. Furthermore, it was shown that endogenous zeaxanthin is more effective than ␤-carotene. Our results suggest that carotenoids exert their protective function as antioxidants to inactivate UV-B-induced radicals in the photosynthetic membrane.

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Ultraviolet-B Radiation and Photosynthesis

Cited by 40 publications

References 121 publications

Characterization of Stomatal Closure Caused by Ultraviolet-B Radiation

Characterization of Stomatal Closure Caused by Ultraviolet-B Radiation

Sudden Exposure to Solar UV-B Radiation Reduces Net CO2 Uptake and Photosystem I Efficiency in Shade-Acclimated Tropical Tree Seedlings

Protection of Photosynthesis against Ultraviolet-B Radiation by Carotenoids in Transformants of the CyanobacteriumSynechococcus PCC79421

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