Illuminating Study Reveals How Plants Respond to Light

November 23, 2007
Illuminating Study Reveals How Plants Respond to Light

Two proteins known as FHY3 and FAR1 bind to DNA in a plant cell and cause production of two other proteins known as FHY1 and FHL. When hit with far red light, a light-sensitive protein called phytochrome A (phyA) changes its shape. This shape change allows it to bind to FHY1 and FHL. FHY1 and FHL then carry the activated phyA into the cell nucleus. From there, phyA is able to initiate the plant's developmental responses to light such as growth, flowering and straining towards the light. Credit: Zina Deretsky, National Science Foundation

Most of us take it for granted that plants respond to light by growing, flowering and straining towards the light, and we never wonder just how plants manage to do so. But the ordinary, everyday responses of plants to light are deceptively complex, and much about them has long stumped scientists.

Now, a new study "has significantly advanced our understanding of how plant responses to light are regulated, and perhaps even how such responses evolved," says Michael Mishkind, a program director at the National Science Foundation (NSF). This study, which was funded by NSF, will be published in the November 23, 2007 issue of Science.

By conducting experiments with Arabidopsis--a small flowering plant widely used as a model organism--the researchers discovered that the plant prepares to respond to light while it is still in the dark, even before it is exposed to light. This preparation involves producing a pair of closely related proteins (known as FHY3 and FAR1) that increase production of another pair of closely related proteins (known as FHY1 and FHL) that had been identified in previous studies as critical participants in the plant's light response.

Haiyang Wang, a member of the research team from Boyce Thompson Institute for Plant Research, says that the plant probably stockpiles these proteins needed for light responses in the dark for the same reason that a traveler fills his car's gas tank the night before a morning journey: in order to be able to get going, without delay, at first light.

With a plant so primed in the dark, it detects and responds to light via the following steps:

-- Light-sensing pigment proteins known as phytochrome A located in the cytoplasm of plants cells detect the light in the far-red end of the spectrum.

-- The phytochrome A is activated through a change in shape that allows it to bind to FHY1 and FHL.

-- The binding of FHY1 and FHL to phytochrome A results in the accumulation of phytochrome A in the cell nucleus, possibly by helping to import phytochrome A into the nucleus.

-- The activated phytochrome A changes the activity of genes located in the cell nucleus that govern plant growth and development.

-- Resulting changes in gene expression produce the plant's developmental responses to light, such as growth, flowering and straining towards the light.

Although these steps had been identified in previous studies, the discovery of how FHY3 and FAR1 regulate plant responses to light adds an important new dimension to our understanding of them.

Moreover, the researchers also discovered the existence of a negative feedback loop between accumulations of phytochrome A in the cell nucleus and the FHY3 and FAR1 proteins that prime the plant's light response system: the more phytochrome A accumulates in the nucleus, the less FHY3 and FAR1 proteins are produced, and so less phytochrome A is imported into the nucleus. "This feedback loop serves as a built-in brake that limits the flow of light responses," says Wang.

"I can't explain why nature created such a complex process to trigger a plant's light responses," says Wang with a sigh. Among the process's complexities is a resemblance between FHY3 and FAR1 proteins and certain enzymes produced by some mobile DNA elements or so-called "jumping genes." (Jumping genes are so named because they can move between various positions in a cell's genetic code.) "This resemblance initially puzzled the research team when we were trying to identify the molecular function of the proteins," says Wang.

Nevertheless, the resemblance between the FHY3 and FAR1 proteins and jumping gene enzymes may represent a biological blessing in disguise. Why? Because the researchers now believe that they have built a convincing case that FHY3 and FAR1 may have evolved from the jumping gene material. If indeed the proteins did so, this important chapter in evolution may have helped make possible the establishment of flowering plants on earth, says Wang.

Source: NSF

4.6 /5 (51 votes)  

Filter


Move the slider to adjust rank threshold, so that you can hide some of the comments.


Display comments: newest first

HenisDov
Nov 25, 2007

Rank: 4 / 5 (1)
My elsewhere comment re Origin of Circadian Rhythm applies neatly here, too. The mechanism involved in the absorption of energy by the archae genes is the life-source, the energy contents of the package, the living gene.

It all boils down to comprehending that genes-genomes are living organisms:

Origin Of Circadian Rhythm:

Innate Gene-Genome Characteristic...

Re Genes-Genome "Oscillating" see

http://www.physor...572.html

But circadian rhythm may be innate gene-genome characteristic, inborn/brought-about at the energetic conditions during the genesis of genes in the process of phasing from chemical olygomer to replicating life, genes, base life energy packages .....

See

http://blog.360.y...Q--?cq=1&p=372

Chapter I, G. Life's Drive and Purpose

"1. If one accepts, intuitively and logically, Pasteur's observation that all life must come from previously existing life, then the answer to "what makes a mono- and poly-cell life-form a Life" is the answer to "what makes some molecular associations in cells LIVES", and vice versa. It is the "lifehood" of genes that makes us and all other forms of life on Earth living organisms, and evolution has been the route of Life's ever more complexing progress since the first replication of the first gene."

Respectfully,

Dov Henis
arlene
Nov 25, 2007

Rank: not rated yet
that's an interesting read, I guess Ill share this information with my Poulsbo florist.
Rank 4.6 /5 (51 votes)
Tags

Relevant PhysicsForums posts

More news stories

WWF urges banks to block Sakhalin oil plan and save whales

Environment group WWF on Thursday urged three European banks to block Russian giant Sakhalin Energy's plan to build an oil drilling platform that the group claims could harm the endangered grey whale.

Biology / Ecology

created 55 minutes ago | popularity not rated yet | comments 0

Ultraviolet protection molecule in plants yields its secrets

Lying around in the sun all day is hazardous not just for humans but also for plants, which have no means of escape. Ultraviolet (UV) radiation from the sun can damage proteins and DNA inside cells, leading ...

Biology / Plants & Animals

created 3 hours ago | popularity 5 / 5 (3) | comments 0 | with audio podcast

Deadly bird parasite evolves at exceptionally fast rate

A new study of a devastating bird disease that spread from poultry to house finches in the mid-1990s reveals that the bacteria responsible for the disease evolves at an exceptionally fast rate. What's more, ...

Biology / Biotechnology

created 1 hour ago | popularity 5 / 5 (2) | comments 0 | with audio podcast

Decoding the molecular machine behind E. coli and cholera

Scientists from Queen Mary, University of London have discovered the workings behind some of the bacteria that kill hundreds of thousands every year, possibly paving the way for new antibiotics that could treat infections ...

Biology / Cell & Microbiology

created 1 hour ago | popularity not rated yet | comments 0 | with audio podcast

New research reveals why fishermen keep fishing despite dwindling catches

Half of fishermen would not give up their livelihood in the face of drastically declining catches according to research led by the University of East Anglia (UEA).

Biology / Ecology

created 1 hour ago | popularity not rated yet | comments 0


Anyone can learn to be more inventive, cognitive researcher says

There will always be a wild and unpredictable quality to creativity and invention, says Anthony McCaffrey, a cognitive psychology researcher at the University of Massachusetts Amherst, because an "Aha moment" is rare and ...

Cannabis use doubles chances of vehicle crash

Drivers who consume cannabis within three hours of driving are nearly twice as likely to cause a vehicle collision as those who are not under the influence of drugs or alcohol claims a paper published today in the British ...

Study says children of women exposed to chemotherapy in pregnancy develop as well as other children

A study published Online First by The Lancet Oncology, and linked to The Lancet Series on cancer in pregnancy, shows that children of women exposed to chemotherapy while pregnant develop as well as children in the genera ...

FBI file: Steve Jobs was considered for govt post

(AP) -- FBI background interviews of some people who knew Apple co-founder Steve Jobs reveal a man driven by power and alienating some of the people who worked with him.

FDA outlines path for lower-priced biotech drugs

(AP) -- The Food and Drug Administration is preparing to review the first lower-cost versions of biotech drugs, expensive medications which have never before faced generic competition.

LinkedIn's 4Q earnings strong, revenue doubles

(AP) -- LinkedIn reported a strong fourth quarter as the online professional-networking service added 14 million members. Its net income and revenue beat Wall Street's expectations.