Scientists can switch on plants' response to light
Let there be light - or not

Date:
October 6, 2021
Source:
University of California - Riverside
Summary:
Scientists have figured out how plants respond to light and
can flip this genetic switch to encourage food growth, even
in shade. The discovery could help increase food supply for an
expanding population with shrinking opportunities for farming.



FULL STORY ========================================================================== Scientists have figured out how plants respond to light and can flip
this genetic switch to encourage food growth. The discovery could
help increase food supply for an expanding population with shrinking opportunities for farming.


==========================================================================
The research on this genetic switch, led by UC Riverside, has now been published in the journal Nature Communications.

Almost every aspect of plant growth and development is influenced
by light.

Plants are able to sense light, as well as temperature, with a protein
called phytochrome B. This protein conveys light information into the cell
that changes the expression of genomes, altering plant growth. However, phytochrome B cannot interact directly with the plant's DNA. For that,
plant cells rely on a family of eight proteins called PIFs.

"The activity of these PIFs is directly controlled by phytochrome,"
said lead study author and UCR botany professor Meng Chen. In addition
to controlling the amount of PIFs that accumulate in plant cells, the scientists have learned that when phytochrome B is activated by light,
it inhibits the activity of the PIFs.

"PIFS are like chefs in a restaurant. You can regulate the number
of them. Get rid of half, for example and you reduce the restaurant's productivity," Chen explained. "Alternatively, you could keep all chefs --
in our case, PIFs -- but tie up their hands. That could also slow down
their work the same as getting rid of half of them. That's what we're
saying." The scientists also found another key component of plants'
light response. PIFs have two parts; one part that binds to genes, and
one that activates the genes, which tell the plant to perform different functions such as growing or flowering. This study found the precise
location of these activator regions - - the first time this has been
done in plant cells.



==========================================================================
To find this activation region, Chen's team chopped the protein into
many small pieces. Then, they examined whether any of the pieces were
able to activate genes and found that one of them was. For more detail,
the scientists then changed the amino acids on a PIF, where they believed
the activator region to reside, and observed how the plant responded. This allowed them to be sure where the gene activator region is located as
well as how it is built.

"This approach allowed us to surprisingly recognize the similarities
between this part of the PIF in plants and a tumor-suppressing protein
in humans," Chen said. In fact, Chen said the basic gene activation
mechanisms in plant, yeast, and animal cells bear remarkable similarities
to one another.

"Plants, animals, and fungi (like baker's yeast) all evolved from a
common ancestor," Chen said. "Genetic information in DNA converts to
RNA to protein, and that basic function is conserved through these gene activators across three kingdoms of life, before plants, animals and
fungi diverged." One of the biggest reasons to study these cellular
functions is to manipulate them. In this case, the discovery could allow scientists to turn light and temperature-related genes on and off to
benefit crop growers.

Part of the strategy to increase crop yields is to grow more plants per
acre of land. Currently, if you place crops too close together, plants
can "see" the competing neighbors through their shade. Then plants will
use more energy for growing taller toward the light, but not necessarily
for maximizing leaf growth and seed production.

Alternatively, if plants can ignore their neighbors and concentrate on
leaf and seed production instead of growing taller, growers can increase
yield on the same acreage.

"You don't want only stems to grow, you want yield," Chen said. "For that, plants need energy to make leaves so they can increase photosynthesis,
the process of making food out of sunlight. You want the right part
of the plant to grow." Chen's group demonstrated that by reducing the
activity of PIF proteins, they could slow down stem growth. This study
thus uncovered a precise way to make the plants grow shorter, so that
seeds, fruit and edible portions of the plant can grow, even in shade.

"Now we know how plants turn genes on and off in response to changes in
light and temperature," Chen said. "It's the first step toward controlling their responses to light and temperature, and making them more tolerant
of different, sometimes challenging environments in a changing climate." ========================================================================== Story Source: Materials provided by
University_of_California_-_Riverside. Original written by Jules
Bernstein. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Chan Yul Yoo, Jiangman He, Qing Sang, Yongjian Qiu, Lingyun Long,
Ruth
Jean-Ae Kim, Emily G. Chong, Joseph Hahm, Nicholas Morffy, Pei Zhou,
Lucia C. Strader, Akira Nagatani, Beixin Mo, Xuemei Chen, Meng Chen.

Direct photoresponsive inhibition of a p53-like transcription
activation domain in PIF3 by Arabidopsis phytochrome B. Nature
Communications, 2021; 12 (1) DOI: 10.1038/s41467-021-25909-5 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211006080559.htm

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