here - First Legume Society Conference (LSC1)

Book of Abstracts First Legume Society Conference 2013: A Legume Odyssey Novi Sad, Serbia, 9-11 May 2013
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The role of signal molecules in defence response of pea (Pisum sativum L.) to pea aphid
(Acyrthosiphon pisum Harris) infestation
Van Chung Mai 1,2 , Iwona Morkunas 1
1 Department of Plant Physiology, Poznań University of Life Sciences, Poznań, Poland
2 Department of Plant Physiology, Faculty of Biology, University of Vinh, Vinh, Vietnam
Pea aphid (Acyrthosiphon pisum Harris) is a destructive pest of leguminous plants worldwide.
Damages of pea seedlings leaves (Pisum sativum L.cv. Cysterski) by pea aphid A. pisum were
dependent on the intensity and duration of infestation. It has been revealed that in pea seedlings
leaves in responses to A. pisum infestation were induced accumulation of phytohormones that is
salicylic acid (SA), jasmonic acid (JA), ethylene (ET), and production of reactive oxygen/nitrogen
species (ROS/RNS) such as hydrogen peroxide (H2O2) and nitric oxide (NO). Following aphid
infestation, these signal molecules were induced at different points of time. Strong generation of
H2O2 and JA were observed in pea seedlings leaves at 24 hpi. In turn, after the induction of ET
and NO at 48 hpi in aphid-infested leaves the generation of SA occurred (strongly increased from
72 hpi to 96 hpi). Then, JA and ET were again induced and reached the second maximum levels
at 96 hpi. Therefore, at the point of 96 hpi there was the combined action of three
phytohormones SA, JA and ET in the defense mechanism of pea leaves. In parallel, the increase
in activity of enzymes phenylalanine ammonia-lyase (PAL) and benzoic acid 2-hydroxylase
(BA2H) in the SA synthesis pathway, lipoxygenase (LOX) engaged with the biosynthesis of JA
was similar to the enhanced alteration of these signal molecules. The antioxidant enzymes
superoxide dismutase (SOD) and catalase (CAT) are important elements of the regulation of
H2O2 metabolism in responses to oxidative stress. The increase in activity the antioxidant
enzymes were probably connected with the defensive role of H2O2 and reduction of oxidative
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stress in pea leaves. Furthermore, the accumulation of superoxide anion (O2 ) and semiquinone
radicals was involved in the defense responses of pea leaves to pea aphid. In pea cells, the
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increase generation of O2 played a defensive role to protect against aphid herbivory, whereas
semiquinones may contribute to build-up of a barrier or activate other defense strategies. The
level of these radicals increased progressively in response to the attack of pea aphids. These
aspects contribute to the novel knowledge concerning the identification of regulatory
mechanisms during the plant-aphid interactions.
Acknowledgements
The study is supported by the Polish National Science Centre Project (NCN, grant no. 2011/01/B/NZ9/00074)
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