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Role of Plant
Phenolics in UV-protection
Bornman, Janet1,
Szilágyi, Anna1 and Hideg , Éva 2
Lund University, Lund, Sweden1
Biological Research Center, Szeged, Hungary2
Abstract-
Plant response to ultraviolet radiation (UV) includes induction of UV-absorbing
pigments, which may function as signalling agents, defence against biotic
attack, and as antioxidants. Supplemental UV radiation is effective
in preferentially inducing antioxidant pigments in several plant species.
For example, previous results from barley showed that supplemental UV
radiation increased flavonoid antioxidants up to 500%. The accumulation
and distribution of these biochemical pigment changes can also be assessed
by measuring the penetration of UV radiation inside leaves using quartz
fibre-optic microprobes. Depending on the level of UV radiation, the
UV may also serve to harden the plant against further stress conditions.
Exposure of basil plants to supplemental UV-B (280-315 nm) radiation
during growth resulted in oxidative stress as shown from the production
of reactive oxygen species measured by EPR. However, growth under relatively
low levels of supplemental UV radiation increased plant tolerance to
a short-term, more enhanced level of radiation. Likewise, plant tolerance
also increased upon exposure to a second stress condition, viz. drought.
Consequently, lipid peroxidation products and reactive oxygen in UV-acclimated
as compared to non-acclimated controls were less, and photosynthetic
yield was less affected.
Keywords: ultraviolet
radiation, plant stress, flavonoids
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