Plant scientists study the interaction of heat stress responses in corn


Date:
August 28, 2020
Source:
Iowa State University
Summary:
A new study shows how two responses in separate locations inside
plant cells work in concert to help corn plants respond to heat
stress. The research was made possible by the Enviratron, an
innovative plant sciences facility at Iowa State University that
utilizes a robotic rover and highly controlled growth chambers.



FULL STORY ========================================================================== Environmental extremes driven by climate change create stresses in crops,
and plant breeders are attempting to untangle the genetic factors that
endow plants with tolerance to stress. A new study from Iowa State
University scientists shows how two seemingly unrelated responses in
corn plants interact to help the crop survive heat stress.


==========================================================================
The study, published on Tuesday in the academic journal The Plant
Cell, shows how a response called the unfolded protein response helps
to activate the heat shock response when corn plants are exposed to
hot weather conditions. The two responses operate in different parts
of plant cells, and scientists previously assumed the responses were independent. But data gathered using the Enviratron, a highly controlled
and automated facility at Iowa State equipped with a robotic rover and
growth chambers, allowed the research team to show how one response
influences another.

"These two systems have been thought to operate independently," said
Stephen Howell, Distinguished Professor of Genetics, Development and
Cell Biology and senior author of the study. "We've been able to show
these systems sometimes work together to mitigate damage caused by heat
and to protect the plant from stress." Heat stress causes proteins to
denature and misfold in the endoplasmic reticulum, an organelle inside
cells. Misfolded proteins can be toxic, and their buildup sets off an
alarm that activates the expression of genes that protects plants from
heat stress. A similar response plays out in different locations of
the cell, including the cytoplasm, where excessive heat activates the expression of a different set of genes encoding heat-shock proteins.

The new study shows that, although the two responses take place in
different parts of the cell, they actually work in concert during heat
stress: a powerful transcription factor produced in the unfolded protein response activates the expression of a key factor helping to trigger
the heat shock response.

The scientists found that knocking out the unfolded protein response
made corn plants more susceptible to heat stress and hindered the heat
shock response.

That raises the question if overexpressing the misfolded protein response
could strengthen the ability of corn plants to withstand high heat,
but Howell said doing so may have other undesirable consequences.

"There's a seesaw balance, if you will, between defense and growth,"
he said.

"The more you contribute to defense, the more you sacrifice growth. It may
be that you could provide somewhat greater defense to crops but you might
do so at the expense of growth." In their study, the researchers drew on
data gathered in the Enviratron, a state-of-the-art facility at the ISU
Ag Engineering/Agronomy Research Farm that utilizes a robotic rover that travels through a series of specialized growth chambers that carefully
control the environments in which the plants are raised. Development
of the Enviratron was funded through a grant from the National Science Foundation. Zhaoxia Li, first author of the paper and a postdoctoral
scientist in Howell's lab, said the facility allows researchers to
control variables such as temperature, moisture, light and carbon dioxide concentrations to study their effect on plant development.

Howell said previous scientific papers have described the design and construction of the Enviratron, but this is the first publication in a
journal based on data generated in the facility.

"We hope that studies like this will emphasize the value of conducting
such research under controlled environmental conditions offered by the Enviratron," he said.


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


========================================================================== Related Multimedia:
* YouTube_video:_Enviratron_robot ========================================================================== Journal Reference:
1. Zhaoxia Li, Jie Tang, Renu Srivastava, Diane C. Bassham, Stephen H.

Howell. The Transcription Factor bZIP60 Links the Unfolded Protein
Response (UPR) to the Heat Stress Response (HSR) in Maize. The
Plant Cell, 2020; tpc.00260.2020 DOI: 10.1105/tpc.20.00260 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200828140314.htm

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