'Scents' of alarm: Volatile chemical signals from damaged plants warn neighbors about herbivore attacks
Researchers discover the epigenetic mechanisms of volatile-signal-induced activation of defense genes in plants
Date:
March 10, 2022
Source:
Tokyo University of Science
Summary:
Animals often use highly specific signals to warn their herd about
approaching predators. Surprisingly, similar behaviors are also
observed among plants. Shedding more light on this phenomenon,
researchers have discovered one such mechanism. Using Arabidopsis
thaliana as a model system, the researchers have shown that
herbivore-damaged plants give off volatile chemical 'scents'
that trigger epigenetic modifications in the defense genes of
neighboring plants. These genes subsequently trigger anti-herbivore
defense systems.
FULL STORY ========================================================================== Animals often use highly specific signals to warn their herd about
approaching predators. Surprisingly, similar behaviors are also observed
among plants.
Shedding more light on this phenomenon, Tokyo University of Science
researchers have discovered one such mechanism. Using Arabidopsis thaliana
as a model system, the researchers have shown that herbivore-damaged
plants give off volatile chemical "scents" that trigger epigenetic modifications in the defense genes of neighboring plants. These genes subsequently trigger anti-herbivore defense systems.
==========================================================================
In the wild, many species of animals, especially those with known
predators, signal each other of imminent dangers using a variety of
techniques, ranging from scent to sound. Now, thanks to multiple studies
on the topic, we have reason to believe that plants, too, can sound an
alarm under threat of an attack.
Prior studies have shown that when grown near mint plants, soybean
and field mustard (Brassica rapa) plants display heightened defense
properties against herbivore pests by activating defense genes in their
leaves, as a result of "eavesdropping" on mint volatiles. Put simply,
if mint leaves get damaged after a herbivore attack, the plants in their immediate vicinity respond by activating their anti-herbivore defense
systems in response to the chemical signals released by the damaged mint
plant. To understand this mechanism better, a team of researchers from
multiple Japanese research institutes, including Tokyo University of
Science, studied these responses in Arabidopsis thaliana, a model plant
used widely in biological studies.
"Surrounding undamaged plants exposed to odors emitted from plants eaten
by pests can develop resistance to the pests. Although the induction
of the expression of defense genes in odor-responsive plants is key
to this resistance, the precise molecular mechanisms for turning
the induced state on or off have not been understood. In this study,
we hypothesized that histone acetylation, or the so-called epigenetic regulation, is involved in the phenomenon of resistance development,"
explains Dr. Gen-ichiro Arimura, Professor at the Tokyo University of
Science and one of the authors of the study.
Their findings have recently been published in the journal Plant
Physiology.
First, researchers exposed the plants to b-ocimene, a volatile organic
compound often released by plants in response to attacks by herbivores
like Spodoptera litura. Next, the researchers tried to determine the
exact mechanism of action of volatile-chemical-activated plant defense.
The results were interesting―defense traits were induced in
Arabidopsis leaves, presumably through "epigenetic" mechanisms, which
refer to gene regulation that occurs because of external environmental influences. In this case, the volatile chemicals released by the damaged
plants enhanced histone acetylation and the expression of defense gene regulators, including the ethylene response factor genes "ERF8" and
"ERF104." The team found a specific set of histone acetyltransferase
enzymes (HAC1, HAC5, and HAM1) were responsible for the induction and maintenance of the anti-herbivore properties.
The researchers are excited about their discovery of the role that
epigenetics has to play in plant defense. According to them, the
communication between plants via volatile compounds (known as the
"talking plants" phenomenon) can potentially be applied to organic
cultivation systems. This may increase the pest resistance of plants
and effectively reduce our massive dependence on pesticides.
"The effective use of plants' natural survival strategies in production
systems will bring us closer to the realization of a sustainable society
that simultaneously solves environmental and food problems," concludes
Dr. Arimura.
========================================================================== Story Source: Materials provided by Tokyo_University_of_Science. Note:
Content may be edited for style and length.
========================================================================== Related Multimedia:
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Diagram_of_volatile-signal-induced_activation_of_defense_genes_in_plants ========================================================================== Journal Reference:
1. Haruki Onosato, Genya Fujimoto, Tomota Higami, Takuya Sakamoto,
Ayaka
Yamada, Takamasa Suzuki, Rika Ozawa, Sachihiro Matsunaga,
Motoaki Seki, Minoru Ueda, Kaori Sako, Ivan Galis, Gen-ichiro
Arimura. Sustained defense response via volatile signaling and
its epigenetic transcriptional regulation. Plant Physiology, 2022;
DOI: 10.1093/plphys/ kiac077 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220310115124.htm
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