Watching changes in plant metabolism -- live
Researchers use a new method of in vivo biosensor technology

Date:
August 14, 2020
Source:
University of Mu"nster
Summary:
Almost all life on Earth, e.g. our food and health, depend
on metabolism in plants. To understand how these metabolic
processes function, researchers are studying key mechanisms in the
regulation of energy metabolism. A new method of in vivo biosensor
technology has enabled them to monitor in real time what effects
environmental changes have on the central metabolism of the model
plant Arabidopsis thaliana.



FULL STORY ========================================================================== Almost all life on Earth, in particular our food and our health, depend on metabolism in plants. In order to understand how these metabolic processes function, researchers at the Institute of the Biology and Biotechnology
of Plants at the University of Mu"nster with the participation of the University of Bonn are studying key mechanisms in the regulation of
energy metabolism.

Now, for the first time, a new method of in vivo biosensor technology has enabled them to monitor in real time what effects environmental changes --
for example, light, temperature, aridity, flooding or pest infestation --
have on the central metabolism of the model plant Arabidopsis thaliana
(thale cress).

The study has appeared as an advance publication in the journal The
Plant Cell.


========================================================================== Background and methodology The team of researchers expressed a genetically coded sensor inside the plants in order to make central metabolic
process literally 'visible'. "Because plants appear from the outside
to be very static, they have to be superfast masters of flexibility and adaptation within their cells," says Dr. Janina Steinbeck, lead author
of the study. "We're now able to observe those dynamics live in the
living plant." In order to measure the metabolic process in the plant
and produce images of it, the researchers used in vivo biosensoring, a
method for studying living organisms, tissue or cells in real time. The biosensor consists of a biological recognition element, a protein which specifically binds a molecule to be detected, and a read-out element,
a protein which translates the binding to the recognition element into a
light signal. The biosensor now being used was originally developed for
use in nerve cells. The researchers refined this sensor and developed
it so that it could be used in plants.

The sensor can directly bind and then release the molecules NAD+ and
NADH. The so-called NAD redox system is of paramount importance for
electron transfer during metabolism in almost all living things. The
sensor consists of a fluorescent blue-green protein and a red one, both
of which change their brightness depending on the NAD status in the
cell. The sensor read-out in living cells is carried out with a modern
confocal laser scanning microscope.

The possibility of using NAD in vivo sensing in plants opens up new
options for plant researchers. "For us, this new method is an achievement regarding the methodology because now we can gain a direct understanding
of metabolic processes precisely where they occur in the plant," explains
Prof. Markus Schwarzla"nder, who heads the Plant Energy Biology working
group at the University of Mu"nster. "For example, it was a complete
surprise for us to observe that such a key process as NAD metabolism
changes so fundamentally during an immune reaction," he adds.

Up to now, it had only been possible for the researchers to study this
type of metabolic processes by obtaining extracts from the plants and
analysing them with biochemical methods. In this approach, however, cells
and tissue are destroyed, and it is no longer possible to trace where
exactly the metabolic changes occurred. Now, the researchers can track
dynamic changes in the redox metabolism -- which, among other functions,
serves to provide energy in the cells -- from specific cell compartments,
here in the cytosol, in the individual cells, up to complete organs
in intact living plants. This approach makes it possible to create a
first NAD redox map of the whole plant and to observe redox dynamics in transitions from light to dark as well as changes in the sugar status,
cell respiration and oxygen supply. "As a result, it becomes apparent
just how directly metabolism and environment are linked," says Markus Schwarzla"nder. "What was especially exciting was the new connection to
the immune response, which we previously had practically no idea about,
and which now needs to be studied in more depth." At almost the same
time as the publication in The Plant Cell, a study by researchers in
Hong Kong was published in Nature Communications. In this study, a
different sensor for NAD was expressed inside plants and used to study photosynthesis. The results of both studies support each other. "The information gained through the new method can play a key role in future
in cultivating plants which make our food production more sustainable and contribute to alleviating the effects of climate change. A direct early recognition of stress in agricultural crops might also be possible,"
says Schwarzla"nder, with a view to the future.


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


========================================================================== Journal Reference:
1. Janina Steinbeck, Philippe Fuchs, Yuri Luca Negroni, Marlene
Elsa"sser,
Sophie Lichtenauer, Yvonne Stockdreher, Elias Feitosa Arau'jo,
Johanna B.

Kroll, Jan-Ole Niemeier, Christoph Humberg, Edward N. Smith,
Marie Mai, Adriano Nunes-Nesi, Andreas J. Meyer, Michela Zottini,
Bruce Morgan, Stephan Wagner, Markus Schwarzla"nder. In Vivo
NADH/NAD Biosensing Reveals the Dynamics of Cytosolic Redox
Metabolism in Plants. The Plant Cell, 2020; tpc.00241.2020 DOI:
10.1105/tpc.20.00241 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200814142943.htm

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