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ANTIOxIdANT POTENCY OF LYONISIdE ISOLATEd
FrOM STEMS ANd rHIZOMES OF vAccinium myrtillus
L.
Szakiel Anna1 , Henry Max2 . 1University of Warsaw, Faculty of
Biology, Department of Plant Biochemistry, 1 Miecznikowa St.,
02-096 Warsaw, Poland, szakal@biol.uw.edu.pl; 2Nancy-Uni versité, Structure et réactivité des systèmes moléculaires complexes
(SRSMC), UMR7565 CNRS-UHP, 5 rue Albert Lebrun,
BP: 80403, 54001, Nancy cedex, France
Lyoniside, 9-O-β-D-xylopyranosyl(+)lyoniresinol, is a phenyltetralin
lignan glycoside occurring mainly in woody parts or sempervivent
leaves of various plants. We have isolated it from the
stems and rhizomes of bilberry Vaccinium myrtillus L. Its exclusive
occurrence in winter-persistent organs suggests the possible
role in chemical defence against pathogens and herbivores, protection
against UV-radiation and allelopathic activity if leakage
or exudation to the soil is possible. Indeed, previously we have
demonstrated the antifungal and allelopathic properties of lyoniside.
In the present study, the antioxidant potency of lyoniside
was evaluated through free radical scavenging by using the DPPH
(2,2-diphenyl-1-picrylhydrazyl) method. Reaction was monitored
spectrophotometrically at λ = 517 nm. The scavenging effect exerted
on 0,1 mM DPPH solution ranged from 48% to almost 90%
by lyoniside concentrations from 20 to 200 μg∙ml-1 , respectively.
IC50 was 23 μg∙ml-1 . At the highest concentration tested, the
scavenging activity of lyoniside was found to be 93% of that of
α-tocopherol. Thus, according also to other biological activities,
lyoniside can be regarded as an example of a multifunctional secondary
compound which can be involved solely or synergically in
various mechanisms of plant chemical protection.
IMPOrTANCE OF NITrIC OxIdE ANd HYdrOGEN
CYANIdE IN CONTrOL OF dOrMANCY rELEASING
IN AmArAnthus retroflexus L. SEEdS
Sznigir Paweł 1 , Kępczyński Jan 2 . University of Szczecin, Faculty
of Natural Sciences, Chair of Plant Physiology and Biotechnology;
1 don_paolo@poczta.onet.pl; 2 jankepcz@wp.pl
Nitric oxide (NO) and hydrogen cyanide (HCN) can break dormancy
in Arabidopsis, barley seeds and apple embryos. Freshly
harvested seeds of Amaranthus retroflexus L. are dormant and
this dormancy may be lost during afterripening. The aim of the
study was to determine the role of nitric oxide and hydrogen
cyanide in releasing primary dormancy of Amaranthus retroflexus
L. seeds. Primary dormancy in these seeds was partially
broken by NO+HCN and HCN released from sodium nitroprusside
(SNP) and potassium hexacyanoferrate [Fe(II)CN] respectively.
Nitric oxide, released from S-nitroso-N-acetyl-DLpenicylamine
(SNAP), did not remove dormancy in these seeds.
Nitric oxide scavenger, cPTIO, inhibited seed germination in an
atmosphere enriched with NO+HCN or HCN. Stimulatory effect
of HCN did not appear in the presence of abscisic acid. Inhibitors
of ethylene biosynthesis, CoCl 2 and α-aminoisobutyric acid
(AIB), did not affect seed germination when applied simultaneously
with HCN. However, 2,5-norbornadiene; an inhibitor of
ethylene binding to its receptor, inhibited germination of seeds
preincubated in atmosphere with HCN. The results indicate that
hydrogen cyanide may play a role in the control of primary dormancy
in Amaranthus retroflexus L. seeds. Sensitivity of seeds
to hydrogen cyanide was decreased by abscisic acid. Releasing
dormancy by hydrogen cyanide may require ethylene action and
possibly endogenous nitric oxide.
Plant Physiology and Biochemistry
LIGHT rEACTION OF PHOTOSYNTHESIS IN MESO-
PHYLL ANd BUNdLE SHEATH CHLOrOPLASTS OF
MAIZE IN rESPONSE TO Pb IONS
Wasilewska Wioletta 1 , Bacławska Ilona 2 , Romanowska Elżbieta
2 . 1–2 Warsaw University, Faculty of Biology, Department of
Molecular Plant Physiology, 1 Miecznikowa St., 02-096 Warsaw,
Poland; 1 wiolaw@biol.uw.edu.pl
Maize is a C 4 plant in which two differ structurally and functionally
cell types, mesophyll (M) and bundle sheath (BS),
cooperate during photosynthesis. Mesophyll chloroplasts
are similar to those in C 3-type higher plants, while BS ones
lack grana. Heavy metals, like lead, are one of the major
abiotic stresses and they cause changes in relative levels of
thylakoid components and in the efficiency of photosystems.
Maize plants were grown under two light conditions: low (LL,
50µmol∙m -2 ∙s -1 ) and high (HL, 600µmol∙m -2 s -1 ) light intensity.
Lead (5mM Pb(NO 3) 2) was introduced into detached leaves
with transpiration stream. We observed that accumulation of
Pb ions in the leaves was higher in plants grown under LL
than HL. Effects of Pb ions were independent on light intensity
during growth. PSI activity and amount of LHCI proteins
decreased in response to Pb 2+ and it was more evident in BS
chloroplasts. We propose that in agranal chloroplasts, Pb disturbs
cyclic electron transport and ATP production. A higher
respiration rate in Pb 2+ treated leaves was observed. Fluorescence
parameters and PSII activity were not affected by Pb
ions. Our results could indicate that bundle sheath chloroplasts
were more sensitive to lead toxicity than mesophyll chloroplasts.
The work was supported by Polish Ministry of Science
and Higher Education Grant NN303 393636
THE EFFECT OF EPIBrASSINOLIdE ON THE rOOT
GrOWTH OF TULIPS
Węgrzynowicz-Lesiak Elżbieta. Research Institute of Pomology
and Floriculture, Department of Physiology and Morphogenesis
of Ornamental Plants, 18 Pomologiczna St., 96-100
Skierniewice, Poland, Elzbieta.Wegrzynowicz@insad.pl
Brassinosteroids (BR) induced a wide spectrum of physiological
responses in plants including stem and root elongation, pollen
tube growth, leaf bending and epinasty, the induction of ethylene
biosynthesis. Brassinosteroids might be involved in processes
of regulation of shoot and roots gravitropism. The presence
of typhasterol is known in the pollen of tulips. We showed
that epibrassinolide, stimulated tulip stem growth induced by
auxin. Also the interaction of brassinosteroids and gibberellins
play an important role in tulip stem elongation. In the present
work the effect of epibrassinolide (epiBL) on tulip ‘Apeldoorn’
root growth and ethylene production in root were studied.
Cooled bulbs were used in the experiment. The entire dry outer
scales were removed and each tulip bulb was placed in a small
beaker. Only basal plates and about ¼ of the bulbs were dipped
in distilled water (the control) and epiBL solution at different
concentrations (1- 500 nM). After 3, 7, 11 days the length of
sprout and roots and ethylene production in roots was measured.
The roots of bulbs dipped in distilled water (the control) roots
were long and straight. EpiBL caused inhibition on tulip root
elongation and the roots showed gravitropic disorders and were
twisted. EpiBL in all concentrations did not affect tulip stem
growth as compared to the control. EpiBL had a small stimulatory
effect on ethylene production. The role of epibrassinolide
on root growth in tulips will be discussed.
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