Viral proteins join forces to lower plants' defense 'shields'

Date:
January 25, 2022
Source:
Washington State University
Summary:
New research into how viral proteins interact and can be disabled
holds promise to help plants defend themselves against viruses --
and ultimately prevent crop losses. The study found that viral
proteins interact with each other to help a virus hijack its host
plant and complete its life cycle. When some of these viral proteins
were disabled, the researchers found that the virus could not move
from cell to cell.



FULL STORY ==========================================================================
New research, led by Washington State University scientists, into how
viral proteins interact and can be disabled holds promise to help plants
defend themselves against viruses -- and ultimately prevent crop losses.


==========================================================================
The study published in Frontiers in Plant Sciencefound that viral
proteins interact with each other to help a virus hijack its host plant
and complete its life cycle. When some of these viral proteins were
disabled, the researchers found that the virus could not move from cell to cell. These proteins are also doing double duty, inducing disease as well.

"These silencing suppressor proteins are interacting with each other
in a seamless, highly coordinated lockstep dance to help the virus in
overcome host defense," said WSU virologist Hanu Pappu, the senior author
on the paper.

Insights into the dynamics of these interactions could provide clues
for blocking them, Pappu added.

"We are using genome editing approaches to do exactly that," he said. "The
more we understand about how these viruses bring down defensive 'shields'
and cause disease, the better chance we have of saving plants from viral invaders." A silent, behind-the-scenes arms race between plants and the viruses that prey on them has been going on for millions of years. Viral diseases cost more than a billion dollars in losses annually to food,
feed, and fiber crops worldwide, according to the Food and Agriculture Organization (FAO) of the United Nations.



========================================================================== Plants have developed a sophisticated defense system to protect themselves
from infection, involving highly choregraphed cellular events that are triggered by viral attack, Pappu said. Plants use a molecular defense
called RNA interference, RNAi for short, that chops incoming viral nucleic acid, preventing the virus from commandeering host cells. Viruses in
turn evolved, producing molecules called 'silencing suppressor proteins'
that can disable their hosts' RNAi defenses.

"Star Trek's Federation-versus-Klingons is playing out in real life," said Pappu. "When the plant senses an attack by a virus, its 'shields' go up.

Viruses are finding ways to lower the shields or slip through them and eventually take over the plant." Pappu, the Chuey Endowed Chair and
Samuel H. Smith Distinguished Professor in WSU's Department of Plant
Pathology, studies viral proteins that suppress or evade plant defenses, ultimately devising ways to help plants repel pathogens.

He and his team have been studying a group of pathogens called
geminiviruses - - among the most crop-destructive viruses in many parts
of the world.

Lead author Ying Zhai, a WSU research associate, set out to identify
which viral proteins are suppressing defenses and understand how these molecules interact with other viral proteins upon infection. Working with Anirban Roy and his team at the Indian Agricultural Research Institute,
she examined a specific, damaging geminivirus, the Croton yellow vein
mosaic virus. Ying and Roy learned where the viral silencing suppressor is located within cells, how it interacts with cells and brings on symptoms,
and how it helps the virus move from cell to cell.

Using a technique called confocal microscopy, which focuses a tight
beam of light on a small target area, co-author Dan Mullendore at WSU's Franceschi Microscopy and Imaging Center studied individual viral proteins
and where they localize inside host cells.

While most viruses make one protein with a specific function to defeat
their host, Zhai and Roy found that this geminivirus contained not just
one but four different proteins that take part in bringing down plant
defenses. Using highly sensitive molecular and microscopic methods, they
found that these viral proteins were interacting to help the virus. When
some were disabled, the virus could not spread in the plant.

Other co-authors on the study include Hao Peng at the WSU Department
of Plant Pathology; and Gurpreet Kaur, Bikash Mandal, and Sunil Kumar
Mukherjee of the Advanced Center for Plant Virology, Indian Agricultural Research Institute, New Delhi.

The project was supported by the U.S. Department of Agriculture's National Institute of Food and Agriculture Hatch Act funding.

========================================================================== Story Source: Materials provided by Washington_State_University. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Ying Zhai, Anirban Roy, Hao Peng, Daniel L. Mullendore, Gurpreet
Kaur,
Bikash Mandal, Sunil Kumar Mukherjee, Hanu R. Pappu. Identification
and Functional Analysis of Four RNA Silencing Suppressors in
Begomovirus Croton Yellow Vein Mosaic Virus. Frontiers in Plant
Science, 2022; 12 DOI: 10.3389/fpls.2021.768800 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220125112537.htm

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