Abstract
Many plant species are able to acclimate to changes in ultraviolet-B radiation (UVB) (290-320 nm) exposure. Due to the wide range of targets of UVB, plants have evolved diverse repair and protection mechanisms. These include increased biosynthesis of UVB screening compounds, elevated antioxidant activity and increased rates of DNA repair. We have shown previously that Brassica napus L. cv Topas plants can acclimate quite effectively to environmentally relevant increases in UVB through the accumulation of specific flavonoids in the leaf epidermis. However, B. napus was found to lose other flavonoids when plants are exposed to ultraviolet-A radiation (UVA) (320-400 nm) and/or UVB (Wilson et al. [1998] Photochem. Photobiol. 67, 547-553). In this study we demonstrate that the levels of all the extractable flavonoids in the leaves of B. napus plants are decreased in a dose-dependent manner in response to UVA exposure. Additionally, the accumulation of the extractable flavonoids was examined following a shift from photosynthetically active radiation (PAR) + UVA to PAR + UVB to assess if preexposure to UVA affected UVB-induced flavonoid accumulation. UVA preexposures were found to impede UVB-induced accumulation of some flavonoids. This down regulation was particularly evident for quercetin-3-O-sophoroside and quercetin-3-O-sophoroside-7-O-glucoside, which is interesting because quercetins have been demonstrated to be induced by UVB and correlated with UVB tolerance in some plant species. The photobiological nature of these UVA-mediated effects on flavonoid accumulation implies complex interactions between UVA and UVB responses.
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Claims 4
Claim · model-written summary
UVA decreased all extractable leaf flavonoids in a dose-dependent manner.
- Taxon
- B. napus
_Brassica_napus_-_Habit.jpg?width=60)
Brassica napuse0 - Organ / stage
- leavese0
- Treatment
- UVA exposuree0
- Outcome
- levels of all the extractable flavonoidse0
- Direction
- decreasede0
- Qualifier
- in a dose-dependent mannere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
_Brassica_napus_-_Habit.jpg?width=500)
Verbatim
e0“the levels of all the extractable flavonoids in the leaves of B. napus plants are decreased in a dose-dependent manner in response to UVA exposure.”
Claim · model-written summary
UVA preexposure impeded UVB-induced accumulation of some flavonoids.
- Taxon
- B. napusBrassica napuse1
- Treatment
- UVA preexposurese0
- Outcome
- UVB-induced accumulation of some flavonoidse0
- Direction
- impedee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“UVA preexposures were found to impede UVB-induced accumulation of some flavonoids.”
e1“B. napus plants”
Claim · model-written summary
UVA preexposure particularly downregulated quercetin-3-O-sophoroside accumulation.
- Taxon
- B. napusBrassica napuse2
- Treatment
- UVA preexposurese1
- Outcome
- quercetin-3-O-sophorosidee0
- Direction
- down regulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This down regulation was particularly evident for quercetin-3-O-sophoroside and quercetin-3-O-sophoroside-7-O-glucoside”
e1“UVA preexposures were found to impede UVB-induced accumulation of some flavonoids.”
e2“B. napus plants”
Claim · model-written summary
UVA preexposure particularly downregulated quercetin-3-O-sophoroside-7-O-glucoside accumulation.
- Taxon
- B. napusBrassica napuse2
- Treatment
- UVA preexposurese1
- Outcome
- quercetin-3-O-sophoroside-7-O-glucosidee0
- Direction
- down regulatione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This down regulation was particularly evident for quercetin-3-O-sophoroside and quercetin-3-O-sophoroside-7-O-glucoside”
e1“UVA preexposures were found to impede UVB-induced accumulation of some flavonoids.”
e2“B. napus plants”
The same questions in other papers
uv · molecular: metabolites · Brassica napus (oilseed rape)Positive and negative results
1 in the opposite direction
- positive
uv · quality: phytochemicals · Brassica napus (oilseed rape)Positive and negative results
3 in the opposite direction
- positive
- positive
- positive
radiation · molecular: metabolites · Brassica napus (oilseed rape)Results agree
2 papers in the same direction as this paper
- negative
- no effect
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.