Page 25 - BOOK OF PROGRAM ICAGRI 2

Abstract Invited Speaker

Prof. Hasegawa Koichi
Environmental Biology, Chubu University, Japan

Molecular genetics of the nematicidal action of the natural

compound α-terthienyl using Caenorhabditis elegans

Koichi Hasegawa
Department of Environmental Biology, College of Bioscience &
Biotechnology,
Chubu University, 1200 Matsumoto, Kasugai, Aichi 487-8501 Japan

Abstrect: Global agricultural losses caused by plant parasitic nematodes
(PPNs) have been estimated at US$100 billion annually. As the availability of
registered nematicides are being sequentially limited, development of
alternative management strategies against PPNs is urgently required, with an
emphasis on eco-friendly options. While marigolds (Tagetes spp.) have been
utilized as effective antagonistic plants for a long time, their nematicidal action
is still not well understood. α-terthienyl is an allelochemical derived from the
roots of marigold, which is thought as a main compound responsible for the
nematicidal activity of marigold. Oxygen-dependent phototoxicity of α-
terthienyl is thought to exert nematicidal activity, however, α-terthienyl is to be
incorporated into agricultural fields as a nematicidal agent, photoactivation is
unlikely to occur.
First, we investigated the nematicidal activity of α-terthienyl against second
stage juveniles of the root-knot nematode Meloidogyne incognita, and adult and
dauer larvae of the model organism Caenorhabditis elegans. M. incognita
second stage juveniles and C. elegans dauer larvae are morphologically
specialized to be able to survive harsh conditions. Nematode bodies in these
stages were covered with thick cuticle and didn’t show feeding behavior. As
reported previously, α-terthienyl action was much higher after photoactivation.
Surprisingly, α-terthienyl was still effective especially against C. elegans dauer
larvae and M. incognita second stage juveniles even without photoactivation.
Next, we studied expressions of the detoxification enzyme glutathione S-
transferase (GST) and superoxide dismutase (SOD) in C. elegans responding to
the α-terthienyl. These enzymes are recognized to play a major role in protecting
organisms against a wide variety of oxidative toxicants. Quantitative RT-PCR
analysis showed these enzymes were induced well after treated with α-
terthienyl. The susceptibility of nematodes to α-terthienyl changed when the
expression of GST and SOD was induced or suppressed by RNA interference.
To analyze nematicidal action of the α-terthienyl in vivo, we constructed
transgenic C. elegans expressing detoxification enzymes tagged with GFP
reporter proteins, and treated them with α-terthienyl. We found clearly that
expressions of these enzyme restricted in C. elegans hypodermis following
treatment with α-terthienyl.

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