Nature Subissue: The secret language of decoding photosynthesis

For decades, scientists have been plagued by signals from plants that initiate photosynthesis, the process of
converting sunlight into sugar.
Researchers at the University of California, Riverside, have now decoded these previously opaque signals
.

Botanists have known for half a century that the command center of plant cells — the nucleus — sends instructions to other parts of the cell to force them to photosynthesize
.
These instructions come in the form of proteins, without which plants would not turn green or grow
.

"Our challenge is that the nucleus encodes hundreds of proteins that contain the building blocks
of smaller organelles.
Determining which signals trigger photosynthesis is like finding a needle in a haystack," said
Meng Chen, a professor of botany at UC San Diego.

Scientists in Chen's lab discovered the process
of four of these proteins.

Previously, Chen's team demonstrated that certain proteins in the nucleus of plants are activated by light, initiating photosynthesis
.
These four newly discovered proteins are part of this reaction, and they send signals that convert small organs into chloroplasts, which produce growth-promoting sugars
.

Researchers liken the entire process of photosynthesis to a symphony
.

"The conductors of the symphony are proteins called photoreceptors in the nucleus, which respond to
light.
We show in this paper that both red and blue photoreceptors initiate symphony
.
They activate genes
that encode the building blocks of photosynthesis.
”

In this case, the unique situation is that the symphony is performed
by local (core) and remote musicians in two "rooms" of the cell.
Therefore, conductors (photoreceptors) that exist only in the nucleus of an atom must send some information
to musicians located at a distance.
This last step is controlled
by four newly discovered proteins from the nucleus to the chloroplast.

The study was funded by the National Institutes of Health in the hope that it will help cure cancer
.
This hope is based on similarities between chloroplasts
in plant cells and mitochondria in human cells.
Both organelles provide fuel for growth and both contain genetic material
.

Currently, many studies describe communication
from organelles to nuclei.
If there is a problem with organelles, they send signals
to the nucleus "headquarters.
" We know very little
about the regulatory signals of activity sent from the nucleus to organelles.

"The nucleus may control the expression of mitochondrial and chloroplast genes in a similar way, so the principles we learn from the nucleus-chloroplast communication pathway may further deepen our understanding
of how the nucleus regulates mitochondrial genes and their dysfunction in cancer.
"

Understanding how photosynthesis is controlled has implications that go beyond disease research
.
A human settlement on another planet may require indoor farming and create a light scheme to increase the yield
of that environment.
More immediately, climate change poses challenges
for crop growers on the planet.

"The reason we can survive on this planet is because organisms like plants can photosynthesize
.
Without them, there would be no animals, including humans
.
"The ability to fully understand and control plant growth is critical
to food security.
"