UV‐B Resistance of Plants Grown in Natural Conditions

Pescheck, Frauke; Bilger, Wolfgang

doi:10.1002/9781119312994.apr0733

Cited by 7 publications

(6 citation statements)

References 322 publications

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“…In the present experiment, the diurnal rhythm throughout the day verifies 50% changes of the flavonoid index within a few hours, which is enormously fast. Previously, changes up 18% in UV-absorbing compounds were described in relation to the ozon depletion (Pescheck & Bilger, 2020). It remains unclear if there is a delocalization or a modification of the compounds, for example, an oxidation or a degradation followed by a new synthesis.…”

Section: Discussionmentioning

confidence: 99%

Rapid adjustment in epidermal UV sunscreen: Comparison of optical measurement techniques and response to changing solar UV radiation conditions

Neugart

Tobler

Barnes

2021

Physiologia Plantarum

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The accumulation of soluble and cell-wall bound UV-absorbing compounds (i.e., flavonoids) in the epidermis and the mesophyll of leaves is a response of plants to UV exposure. These compounds are known to function in UV screening, but they are also of potential value for food quality. One way to non-destructively monitor UV screening in leaves is by optical methods, from which UVA-PAM and Dualex instruments stand out. The degree and rapidity to which plants can modulate UV screening in response to fluctuating solar UV conditions is poorly understood. In this study, okra plants were exposed to two solar radiation treatments (near-ambient UV [+UV] and attenuated UV [ÀUV]) and the epidermal UV transmittance (T UV ; UVA-PAM) and flavonoid index (Dualex) were measured in the youngest and second youngest mature leaves over three consecutive days and within an individual day. The day-to-day (measured near solar noon) and diurnal (over the course of a day) measurements of leaf optical properties indicated that T UV decreased and flavonoid index increased in the adaxial epidermis $50% until 15:00 CDT then returned close to morning values later in the day. Correlations between UV-B radiation and T UV and flavonoid index revealed highest values 30 min to 1 h prior to the measurements. These findings indicate that plants can respond quickly to fluctuating solar UV conditions and underlines the importance of the harvest-time point for health-promoting compounds in fruit and vegetables. Our findings also indicate that the UVA-PAM and the Dualex instruments are both suitable instruments to monitor rapid changes in UV screening in plants. | INTRODUCTIONUltraviolet radiation (UV; 280-400 nm, including the UV-B [280-315 nm] and UV-A [315-400 nm] wavebands) comprises a relatively small portion of the total solar radiant energy reaching the Earth's surface, but this radiation has the potential to induce a number of photomorphogenic and deleterious effects in plants. These effects include oxidative damage, changes in plant biochemistry, partial inhibition of photosynthesis, and growth reduction (Albert et al., 2011;Hideg et al., 2013;Jordan, 2002). However, plants possess a number of UV protective mechanisms that can mitigate much of the UV-induced damage under normal field conditions (Jansen et al., 1998). In particular, studies have highlighted the regulatory properties of low, ecologically relevant UV-B levels that can trigger structure-dependent accumulation of polyphenols (Neugart et al., 2012;Schreiner et al., 2012). The increase in polyphenols, such as flavonoids and hydroxycinnamic acids,

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Section: Discussionmentioning

confidence: 99%

Rapid adjustment in epidermal UV sunscreen: Comparison of optical measurement techniques and response to changing solar UV radiation conditions

Neugart

Tobler

Barnes

2021

Physiologia Plantarum

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“…However, for flavonoids and carotenoids, a temperature dependence opposite to that observed here has been reported. Low temperature enhanced the formation of UV-screening compounds and flavonoids 51,52 and of V-cycle carotenoids. 53 On the other hand, high temperature (28 °C) has been reported to repress in Arabidopsis thaliana anthocyanin accumulation via the transcription factor HY5.…”

Section: ■ Discussionmentioning

confidence: 99%

Improvement of the Quality of Wild Rocket (Diplotaxis tenuifolia) with Respect to Health-Related Compounds by Enhanced Growth Irradiance

Khoramizadeh,

Garibay-Hernández,

Mock

et al. 2024

J. Agric. Food Chem.

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For healthier human nutrition, it is desirable to provide food with a high content of nutraceuticals such as polyphenolics, vitamins, and carotenoids. We investigated to what extent high growth irradiance influences the content of phenolics, α-tocopherol and carotenoids, in wild rocket (Diplotaxis tenuifolia), which is increasingly used as a salad green. Potted plants were grown in a climate chamber with a 16 h day length at photosynthetic photon flux densities varying from 20 to 1250 μmol m −2 s −1 . Measurements of the maximal quantum yield of photosystem II, F V /F M , and of the epoxidation state of the violaxanthin cycle (Vcycle) showed that the plants did not suffer from excessive light for photosynthesis. Contents of carotenoids belonging to the Vcycle, α-tocopherol and several quercetin derivatives, increased nearly linearly with irradiance. Nonintrusive measurements of chlorophyll fluorescence induced by UV-A and blue light relative to that induced by red light, indicating flavonoid and carotenoid content, allowed not only a semiquantitative measurement of both compounds but also allowed to follow their dynamic changes during reciprocal transfers between low and high growth irradiance. The results show that growth irradiance has a strong influence on the content of three different types of compounds with antioxidative properties and that it is possible to determine the contents of flavonoids and specific carotenoids in intact leaves using chlorophyll fluorescence. The results may be used for breeding to enhance healthy compounds in wild rocket leaves and to monitor their content for selection of appropriate genotypes.

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“…Both groups of plants had similar amounts and composition of phenolic compounds throughout the study period. One explanation for this similarity could be cross-resistance induced by high PFDs from natural sunlight (reviewed in Pescheck & Bilger 2020). PFD is perceived by, among others, the blue light receptors CRYTOCHROME1/ CRYPTOCHROME2 (CRY1CRY2) and blue-light signalling can partly compensate for absent UVR8 signalling (Rai et al 2019).…”

Section: Influence Of Abiotic Factors On Foliar Phenylpropanoid Compo...mentioning

confidence: 99%

“…Plants in their natural environment integrate signals from and simultaneously acclimatise to several environmental variables, such as varying temperature, PFD, and UV radiation. The effects of solar UV‐B radiation on phenylpropanoids are therefore completed or superimposed by other factors (reviewed in Pescheck & Bilger 2020). For example, mainly air temperature, and not daily UV‐B dose (or total PFD), controlled the absorbance of leaf extracts at 330 nm and the content of flavonoids in A. thaliana outdoors over the course of a year (Coffey & Jansen 2019; Pescheck & Bilger 2019).…”

Section: Introductionmentioning

confidence: 99%

Solar UV‐B effects on composition and UV screening efficiency of foliar phenolics in Arabidopsis thaliana are augmented by temperature

Nichelmann

Pescheck

2021

Physiologia Plantarum

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The accumulation of foliar phenolics constitutes one strategy of plants against the potentially harmful effects of ultraviolet-B and A (UV-B, UV-A) radiation. These compounds protect photosensitive tissues by shielding and antioxidative function. It is unknown, however, whether seasonal acclimation to natural conditions may modify the UV-B effect on phenylpropanoid composition and localisation, and thus their screening efficiency. To address this debate, a field experiment with the wildtype of Arabidopsis thaliana accession Landsberg erecta (Ler) was implemented over a whole year with plants exposed to different UV-filter treatments. While seasonal increases of UV-B radiation had a slight negative effect on the amount of hydroxycinnamic acids (HCAs), low temperatures increased foliar HCAs. HCAs, however, did not contribute substantially to seasonal changes of in vivo UV absorbance. Kaempferol and quercetin derivatives increased significantly under ambient UV-B radiation, and low temperature interacted with this effect. A shift of epidermal UV-A shielding from kaempferol to quercetin derivatives was elucidated in UV-B presence. Despite this, a substantial 20-fold increase of quercetin derivatives, during periods with high irradiance and low temperature, did not affect UV absorbance leading to the conclusion that quercetin accumulation was not exclusively in epidermal vacuoles. Using confocal microscopy, the potential occurrence of quercetin in mesophyll cells was demonstrated in plants grown with experimental UV-B radiation at low temperature for the first time in A. thaliana. The presented study discusses the idea that cross-talk of UV-B radiation and temperature might adjust the physiological function of quercetin from an (epidermal) screening to an antioxidant substance. | INTRODUCTIONPlants rely on diverse mechanisms to attain resistance against the potentially deleterious effects of ultraviolet-A and B radiation (UV-A: 315-400 nm, UV-B: 280-315 nm). Among others, the accumulation of phenolic compounds is one important strategy. However, there is an ongoing debate about the major function of foliar phenolic compounds (reviewed in Winkel-Shirley 2002;Agati et al. 2020). Strong arguments support the idea that these aromatic substances have a dual function in leaves: they are antioxidants on the one hand

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UV‐B Resistance of Plants Grown in Natural Conditions

Cited by 7 publications

References 322 publications

Rapid adjustment in epidermal UV sunscreen: Comparison of optical measurement techniques and response to changing solar UV radiation conditions

Rapid adjustment in epidermal UV sunscreen: Comparison of optical measurement techniques and response to changing solar UV radiation conditions

Improvement of the Quality of Wild Rocket (Diplotaxis tenuifolia) with Respect to Health-Related Compounds by Enhanced Growth Irradiance

Solar UV‐B effects on composition and UV screening efficiency of foliar phenolics in Arabidopsis thaliana are augmented by temperature

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