The tobacco plant’s protein could be used to enhance existing crop immune systems. © Dennis Tang

Written by: Aya Kawanishi

Although crops have a general defense mechanism in order to fight
against viruses, their invaders counteract this defense by
suppressing the plant immune response. Evidence from recent studies
implied that plants have developed an additional set of
countermeasures to combat the virus’s immune suppression
tactics.

In order to examine how plants do this, the researchers set out to
find the mechanisms involved. Their results appear in the
Proceedings of the National Academy of Sciences (PNAS).

They found rgs-CaM, otherwise known as “tobacco
calmodulin-like protein”, a calcium-binding messenger protein
(Calmodulin is an abbreviation for “CALcium MODulated
proteIN). In tobacco this protein binds to the viral (RNA
interference) suppressors (molecules produced by the virus that
chemically counteract the plants’ own defenses) and inhibits
the virus from impeding the plant’s defenses.

These findings have the potential to enhance the immune systems for
crops that are vulnerable to pesticide-resistant viruses. The
results of this research may well have an impact beyond tobacco
crops. “Because most viruses encode RNAi suppressors, this
study may contribute to the development of a molecular breeding
strategy to confer resistance other viruses in crops,” said
Associate Prof. Nakahara.

References:

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Kenji S. Nakahara, Chikara Masuta, Syouta Yamada et al. Tobacco
calmodulin-like protein provides secondary defense by binding to
and directing degradation of virus RNA silencing suppressors.
Proceedings of the National Academy of Sciences U S A. 2012 Jun
19;109(25):10113-8. Epub 2012 Jun 4. doi:
10.1073/pnas.1201628109

For further information contact:

—————————————-

Kenji Nakahara

Pathogen-Plant Interactions Group

Research Faculty of Agriculture

Hokkaido University

N9, W9, Kita-ku, Sapporo

060-8589 Japan

Tel: +81-11-706-2490

Email: knakahar@res.agr.hokudai.ac.jp