permaculture

[Lawrence London <lfljvenaura@gmail.com>]

http://bioscriptionblog.com/2018/09/18/plant-electrical-calcium-cascade-defense/
Plant Electrical Calcium Ion Cascade Activates Cell Defense Systems

   -
   - By SterlingAdmin <http://bioscriptionblog.com/author/sterlingadmin/>


   - Arabidopsis
   <http://bioscriptionblog.com/category/model-organisms/arabidopsis/>
   - Calcium <http://bioscriptionblog.com/category/fertilizers/calcium/>
   - Evolution <http://bioscriptionblog.com/category/evolution/>
   - Evolutionary Biology
   
<http://bioscriptionblog.com/category/scientific-fields/evolutionary-biology/>
   - Fluorescent Proteins
   <http://bioscriptionblog.com/category/marker-genes/fluorescent-proteins/>
   - Gene Knockout
   <http://bioscriptionblog.com/category/biotechnology/gene-knockout/>
   - Jasmonic acid
   <http://bioscriptionblog.com/category/molecules/acids/jasmonic-acid/>
   - Metabolomics
   <http://bioscriptionblog.com/category/biotechnology/metabolomics/>
   - Miniposts <http://bioscriptionblog.com/category/miniposts/>
   - Plant Pathology
   <http://bioscriptionblog.com/category/scientific-fields/plant-pathology/>
   - Plants <http://bioscriptionblog.com/category/plants/>
   - Plasmodesmata
   <http://bioscriptionblog.com/category/plants/plasmodesmata/>
   - Proteins <http://bioscriptionblog.com/category/proteins/>
   - Proteomics
   <http://bioscriptionblog.com/category/biotechnology/proteomics/>
   - Resistance <http://bioscriptionblog.com/category/evolution/resistance/>
   - Science <http://bioscriptionblog.com/category/journals/science/>
   - Transgenics
   <http://bioscriptionblog.com/category/biotechnology/transgenics/>
   - United States
   <http://bioscriptionblog.com/category/north-america/united-states/>

When your body is in danger, your cells need to react fast to let everyone
else know. If you stick your hand in a fire, your brain and your muscle
cells have to be notified as soon as possible in order to force the
subconscious pullback from the pain and damage, before you’ve even realized
it’s happening. This intricate dance between different cell types works in
milliseconds, as do many other processes in your body. That’s the benefit
of being an animal.
The Paths Plants Must Take

Plants don’t get that luxury though. They do have their own signaling
mechanisms, but they run on the speed expected of immobile plants. Due to
this, a higher complexity of function is required to respond to different
kinds of threats. Over time, many plants have evolved an intricate network
of signaling molecules that help conduct electrical impulse signals
throughout the plant’s cells and to far off tissues.

This electrical response is dependent on a group of proteins known as
glutamate receptor–like (GLR) proteins, which, as their name suggests,
respond to glutamate activation signals. What researchers at the University
of Wisconsin-Madison were investigating was how these GLR proteins turn on
after the plant is wounded by a pest and how that then leads to the
signaling cascade of calcium ions in particular.

To accomplish this task, the research group modified an *Arabidopsis* plant
so that the calcium sensor proteins have an attached fluorescent component.
Therefore, as calcium ions travel throughout the plant body, the sensors
will light up and show where to and how quickly the calcium ions are
moving. They used a caterpillar consuming a single leaf as the way to start
the defense response. It was noted that said response sometimes only began
once an entire leaf was severed from the rest of the plant at its base,
causing it to begin to leak glutamate.
The Key To Speed

Moving at a speed of around 1 millimeter a second, the propagation of the
calcium ion charge takes around 2 minutes to move to the most distant
leaves from the point of activation. The defense hormone jasmonic acid was
registered to increase production in all notified cells by a significant
amount. The signal was also able to be prevented by treating the wounded
leaf ahead of time with a calcium inhibitor molecule, proving that it is
specifically calcium itself that is critical for electrical signaling and
defense responses.

For a video of the spread of the ions, please see here
<https://3c1703fe8d.site.internapcdn.net/newman/gfx/video/2018/1-blazesofligh.mp4>
.

The transmission of calcium ions also slowed while spreading across the
leaf, before rapidly speeding up throughout the rest of the plant. The
scientists hypothesized that this was due to this initial phase requiring
the calcium ions to travel through the thin cytoplasm membrane in between
the leaf cells known as the plasmodesmata. Knocking out related
transference genes showed an inhibition in the calcium being able to travel
out of the starting leaf into nearby leaves and the overall vasculature,
giving credence to their hypothesis on how the ions start out their journey.

A final thing the team noted is that the two main types of GLR proteins
appear to have separate signaling pathways, with one located in the phloem
and the other in the xylem of the plant, the two primary nutrient pathways.
The former takes sugars and nutrients down from the leaves, while the
latter moves nutrients up from the roots. These distinct regional cascades
suggest that there are independent pathways that each requires activation
of calcium ion responses. Though there is also the possibility that some
sort of communication exists between the cell types to notify them
simultaneously of predatory attacks.
Teaching Defenses

The actual structure of these wound response systems need to be further
researched to find out the true answer. Even so, this deeper understanding
of how plants notify other cells of impending danger and to begin
production of defensive chemicals helps us determine what the best ways to
assist in plant defenses are. Faster calcium signaling is one potential
method to improve plant success rates, along with increasing the output of
caustic pesticides that the plants make themselves.

Every new piece of information opens up new doorways into the world around
us and, in this case, into the greenery of life that surrounds us every
day. The more we can understand about our neighbors in life, the better we
can help them thrive and work with us for our needs as well.