Abstract
The capacity of ultraviolet (UV) radiation to generate reactive oxygen species (ROS) in spinach leaves was studied with fluorescent sensors. Leaf segments were exposed to short-term (15–30 min), narrow-band UV irradiation of various wavelengths between 290–390 nm corresponding to equal numbers of photons and, depending on the wavelength, 18–36 µmol m–2 s–1 quantum flux. This caused 5–30% loss of photosynthesis measured as loss of variable chlorophyll fluorescence. In accordance with previous results, photosynthesis was less affected by longer than by shorter wavelength UV. UV-irradiated leaves were probed for two major representatives of ROS, namely the superoxide radical anion, a product of electron transfer to oxygen, and singlet oxygen, which is usually formed in photosensitised reactions between oxygen and triplet dyes. Both ROS were detected, but the efficacy of UV in promoting their production was different. Formation of superoxide radicals was positively correlated with loss of photosynthesis; more radicals were observed in leaves exposed to shorter UV wavelengths than in leaves irradiated at 370–390 nm, suggesting a functionally damaged electron transport as a possible site of oxygen reduction. Singlet oxygen was, however, mainly inducible in leaves exposed to longer UV wavelengths and was barely induced by 290–300-nm irradiation. The mechanism of singlet oxygen generation by UV radiation in the leaf, reported for the first time, is not clear, but the process does not appear to be linked to the UV-induced damage of photosynthesis.
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Claims 7
Claim · model-written summary
UV irradiation caused a 5–30% loss of photosynthesis in spinach leaves.
- Taxon
- spinach
Spinacia oleraceae0 - Treatment
- narrow-band UV irradiatione2
- Outcome
- loss of photosynthesise1
- Direction
- losse1
- Value
- 5–30%e1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The capacity of ultraviolet (UV) radiation to generate reactive oxygen species (ROS) in spinach leaves was studied with fluorescent sensors”
e1“This caused 5–30% loss of photosynthesis measured as loss of variable chlorophyll fluorescence”
e2“Leaf segments were exposed to short-term (15–30 min), narrow-band UV irradiation of various wavelengths between 290–390 nm”
Claim · model-written summary
Photosynthesis was less affected by longer than by shorter wavelength UV in spinach leaves.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- UVe3
- Outcome
- photosynthesise3
- Direction
- less affectede3
- Comparator
- shorter wavelength UVe3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The capacity of ultraviolet (UV) radiation to generate reactive oxygen species (ROS) in spinach leaves was studied with fluorescent sensors”
e3“photosynthesis was less affected by longer than by shorter wavelength UV”
Claim · model-written summary
Superoxide radical formation was positively correlated with loss of photosynthesis.
- Taxon
- spinachSpinacia oleraceae0
- Organ / stage
- leavese0
- Outcome
- Formation of superoxide radicalse4
- Direction
- positively correlatede4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The capacity of ultraviolet (UV) radiation to generate reactive oxygen species (ROS) in spinach leaves was studied with fluorescent sensors”
e4“Formation of superoxide radicals was positively correlated with loss of photosynthesis”
Claim · model-written summary
More superoxide radicals were observed in spinach leaves exposed to shorter UV wavelengths than in leaves irradiated at 370–390 nm.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- shorter UV wavelengthse5
- Outcome
- radicalse5
- Direction
- moree5
- Comparator
- leaves irradiated at 370–390 nme5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The capacity of ultraviolet (UV) radiation to generate reactive oxygen species (ROS) in spinach leaves was studied with fluorescent sensors”
e5“more radicals were observed in leaves exposed to shorter UV wavelengths than in leaves irradiated at 370–390 nm”
Claim · model-written summary
Singlet oxygen was mainly inducible in spinach leaves exposed to longer UV wavelengths.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- longer UV wavelengthse6
- Outcome
- Singlet oxygene6
- Direction
- mainly induciblee6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The capacity of ultraviolet (UV) radiation to generate reactive oxygen species (ROS) in spinach leaves was studied with fluorescent sensors”
e6“Singlet oxygen was, however, mainly inducible in leaves exposed to longer UV wavelengths”
Claim · model-written summary
Singlet oxygen was barely induced by 290–300-nm UV irradiation in spinach leaves.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- 290–300-nm irradiatione7
- Outcome
- Singlet oxygene7
- Direction
- barely inducede7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The capacity of ultraviolet (UV) radiation to generate reactive oxygen species (ROS) in spinach leaves was studied with fluorescent sensors”
e7“Singlet oxygen was, however, mainly inducible in leaves exposed to longer UV wavelengths and was barely induced by 290–300-nm irradiation”
Claim · model-written summary
Singlet oxygen generation by UV radiation does not appear to be linked to UV-induced damage of photosynthesis.
- Taxon
- spinachSpinacia oleraceae0
- Treatment
- UV radiatione3
- Outcome
- singlet oxygen generatione3
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The capacity of ultraviolet (UV) radiation to generate reactive oxygen species (ROS) in spinach leaves was studied with fluorescent sensors”
e3“The mechanism of singlet oxygen generation by UV radiation in the leaf, reported for the first time, is not clear, but the process does not appear to be linked to the UV-induced damage of photosynthesis”
The same questions in other papers
uv · physiology: photosynthesis · Spinacia oleracea (spinach)Positive and negative results
8 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- negative
6 papers more in this group
See all 10 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.