Newly discovered protein in fungus bypasses plant defenses

Date:
April 25, 2022
Source:
US Department of Agriculture - Agricultural Research Service
Summary:
Scientists have identified a protein that allows the fungus
which causes white mold stem rot in more than 600 plant species to
overcome plant defenses. Knowledge of this protein, called SsPINE1,
could help researchers develop a new, more precise system of
control measures for the Sclerotinia sclerotiorum fungus, which
attacks potatoes, soybeans, sunflowers, peas, lentils, canola,
and many other broad leaf crops.



FULL STORY ==========================================================================
A protein that allows the fungus which causes white mold stem rot in more
than 600 plant species to overcome plant defenses has been identified by
a team of U.S. Department of Agriculture Agricultural Research Service
and Washington State University scientists.


========================================================================== Knowledge of this protein, called SsPINE1, could help researchers develop
a new, more precise system of control measures for the Sclerotinia
sclerotiorum fungus, which attacks potatoes, soybeans, sunflowers, peas, lentils, canola, and many other broad leaf crops. The damage can add up
to billions of dollars in a year of bad outbreaks.

S. sclerotiorum fungi cause plants to rot and die by secreting chemicals
called polygalacturonases (PG), which break down the plant's cell
walls. Plants evolved to protect themselves by producing a protein that
stops or inhibits the fungus' PG, labeled PGIP, which was discovered in
1971. Since then, scientists have known that some fungal pathogens have
a way to overcome plant's PGIP. But they had not been able to identify it.

"What you have is essentially a continuous arms race between fungal
pathogens and their plant hosts, an intense battle of attack,
counterattack and counter- counterattack in which each is constantly
developing and shifting its chemical tactics in order to bypass or
overcome the other's defenses," said research plant pathologist Weidong
Chen with the ARS Grain Legume Genetics Physiology Research Unit in
Pullman, Washington, and leader of the study just published in Nature Communications.

The key to identifying SsPINE1 was looking outside the fungi cells,
according to Chen.

"We found it by looking at the materials excreted by the fungus,"
he said. "And there it was. When we found this protein, SsPINE1,
which interacted with PGIP, it made sense." Then to prove that the
protein SsPINE1 was what allowed Sclerotinia to bypass plants' PGIP,
Chen and his colleagues deleted the protein in the fungus in the lab,
which dramatically reduced its impact.

"I got goosebumps when we found this protein," said Kiwamu Tanaka,
an associate professor in Washington State University's Department of
Plant Pathology and a co-author on the paper. "It answered all these
questions scientists have had for the last 50 years: Why these fungi
always overcome plant defenses? Why do they have such a broad host range,
and why are they so successful?" The discovery of SsPINE1 has opened new avenues to investigate for controlling white mold stem rot pathogens,
including possibly even more effective, more targeted breeding to make
plants naturally resistant to sclerotinia diseases.

And the team has showed that other related fungal pathogens use this
counter- strategy, which only serves to make this discovery even more important.

This research is part of the National Sclerotinia Initiative, a multiorganization effort that ARS created to counterattack S. sclerotiorum because the fungus does so much damage around the world.

The research team also included scientists from USDA-ARS, WSU,
Northwestern A&F University in Shaanxi, China, Wuhan Polytechnic
University in Wuhan, China and Huazhong Agricultural University in Wuhan.


========================================================================== Story Source: Materials provided by US_Department_of_Agriculture_-_Agricultural_Research Service. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Wei Wei, Liangsheng Xu, Hao Peng, Wenjun Zhu, Kiwamu Tanaka, Jiasen
Cheng, Karen A. Sanguinet, George Vandemark, Weidong
Chen. A fungal extracellular effector inactivates plant
polygalacturonase-inhibiting protein. Nature Communications, 2022;
13 (1) DOI: 10.1038/s41467-022- 29788-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220425085716.htm

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