Liming Xiong, Ph.D., Plant Biology,
Oliver Yu, Ph.D,
University of Arizona
Genetics and Plant Physiology,
University of South Carolina
Drought is among the most
devastating and most common
Nitrogen is the main component
of synthetic fertilizers for crops.
Yiji Xia, Ph.D., Genetics,
forms of natural disaster for
Worldwide, the production of
Iowa State University
agriculture. Even on well-irrigated
cultivated land, periodic drought
nitrogen fertilizers consumes
Plant cells respond to invading
is frequently experienced by crop
approximately 5% of global
pathogens via complex signaling
plants during the growing season
natural gas and 2% of all energy
networks. One of the early host
that could result in significant
produced. Biological nitrogen
responses triggered by pathogen
yield losses. Upon encountering
fixation can reduce the application
infection is the production of
drought stress, plants activate
of fertilizers drastically and plays
reactive oxygen/nitrogen species
multiple stress-response
an important role in the nitrogen
(ROS/RNS). This alters cellular
pathways that lead to changes
cycling in the biosphere. Research
redox homeostasis and leads to
in gene expression, movement
in the Yu lab focused on legume
oxidative modifications of cellular
of stomata, and developmental
rhizobia symbiosis, which is the
components. Two Arabidopsis
changes to mitigate the
major contributor to biological
Nudix hydrolases (AtNUDT7
damaging effects of the stress.
nitrogen fixation. Rhizobia are
and AtNUDT6) that function as
Understanding how plants sense
a small group of soil-borne
negative regulators of disease
and respond to drought stress
bacteria that can colonize the
resistance have been found
and identifying the corresponding
roots of legume plants, induce
to modulate the host defense
genes involved in these processes
host plants to form a specific
response through maintenance
will be essential for breeding
structure called root nodules,
of cellular redox homeostasis. To
or engineering stress-resistant
and reduce atmosphere nitrogen
identify additional components
crop plants. Using the mustard
gas into ammonia inside these
involved in redox-mediated
Arabidopsis as a model plant,
nodules. The establishment of this
defense signaling, we have taken
our laboratory is employing
symbiotic relationship requires
a redox proteomics approach to
integrative approaches to isolate
extensive signaling between
identify proteins that undergo
genes that confer stress tolerance
the plants and bacteria. Many
oxidative modifications in
and testing their effectiveness
steps and components of early
Arabidopsis cells subjected to
in increasing plant resistance to
signaling events are still unclear.
treatment with hydrogen peroxide
drought stress.
We recently discovered that
and redox-altering elicitors. The specific flavonoid compounds
redox-sensitive proteins might and miroRNAs played essential
function as a molecular switch to roles in the nodulation process.
regulate biological processes. We Understanding their functions
are currently characterizing several is crucial for deciphering the
redox-sensitive proteins to study mechanisms of symbiosis and
their roles in the redox-mediated may help to transform non-fixing
signaling pathway. plants into better nitrogen fixers.
Detection of differentially oxidized proteins in
H2O2-treated Arabidopsis cells. Shown is a portion
of superimposed 2-D protein gel images. Spots
in pink represent proteins that became oxidized
following the oxidant treatment.
Updates from our Scientists 17
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