Researchers discover contenders in molecular arms race of major plant disease

Researchers have discovered how a tiny viral protein enables the infection of a complex plant, and the finding could lead to understanding viral diseases in other plants, animals and humans, according to a team of Texas A&M AgriLife Research biochemists.

The study is reported this month in the journal eLife.

Dr. Xiuren Zhang's lab in College Station focused on how can defend themselves against viral attacks by experimenting with the effect of on arabidopsis, a model plant widely used in research.

The mosaic virus was studied by Zhang and his team because it readily infects numerous important crops such as corn, tomatoes, peppers and potatoes as well as cotton and landscape flowers. Once the infection begins - causing yellowing in a mosaic pattern and curling leaves - there is no stopping it. The plant dies after a short, unproductive life. The disease spreads easily through insects that feed on the plants.

"We know that in the system, the power exists through the immune system to recognize and kill a virus," Zhang said. "When a virus gets into the host (plant), it hijacks and regulates the host's machinery to produce more and more virus. The host must find some way to fight back against this virus that is making it sick."

"We wondered what allows this virus to take over a whole plant, a complex organism," added Claudia Marcela Castillo-González, a doctoral student who led the research. "The mosaic virus causes a lot of damage. Absolutely everything you can grow to eat can be affected by this family of viruses."

She noted that the virus is a simple organism with only seven genes, whereas the plant it infected in the study has more than 25,000 genes.

To understand this molecular arms race, as the team called it, the researchers explained the contenders in this battle:

A geminivirus, so named because it looks like twins but actually is only one, is a DNA virus that carries a protein called TrAP to stop transcriptional gene silencing.

Transcriptional gene silencing is what normally serves as a pathway for immunity against DNA viruses. If the virus is silenced, the plant isn't made sick.

KYP hangs on to macromolecules consisting of viral DNA and histone proteins, and combats the infection by ensnaring and silencing the DNA.

However, the virus has TrAP, which targets KYP and frees the viral DNA from the snare to propagate and cause .

"All the eukaryotes (most living organisms) have a nucleus, which is a compartment where we keep the DNA, which has to be packed because the molecule is extremely long," Castillo-González said. "The packing turns out to be informative - just as informative almost as is the sequence. It turns out that the way it's packed will allow a gene to be expressed or not."

Visually, the DNA is wrapped like yarn on a spool, according to Castillo-González.

"If they are open and relaxed, then the DNA is going to be accessible. However, if those spools are very tightly packed, they don't allow space for the DNA to be read. In that case, that part of the genome will never be read or expressed. It's as if you didn't have that gene," she said. "The KYP protein maintains the condensation of the DNA, but TrAP protein fights KYP and relaxes it. And this is extremely remarkable.

"KYP evolves as a critical immune system to control invading nucleic acids. This is important on several levels as we and other researchers continue to study this finding," Castillo-González added. "One, to advance science, because we didn't know this kind of mechanism happened. Second, as a potential tool to target this and prevent it from spreading and causing agricultural loss. And third, as a tool to study this mechanism—how chromatin (the material that makes chromosomes) moves and how it is regulated in the cells of humans and all living organisms."


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Plants can 'switch off' virus DNA

Journal information: eLife

Citation: Researchers discover contenders in molecular arms race of major plant disease (2015, September 27) retrieved 16 July 2019 from https://phys.org/news/2015-09-contenders-molecular-arms-major-disease.html
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JVK
Sep 27, 2015
The proliferation of viruses links the spectrum of protein-coding variation across generations in species from microbes to humans, which is why "...the spectrum of protein-folding chemisty is considerably different today compared to what existed as recently as 200 to 400 generations ago."


JVK
Sep 27, 2015
That claim was linked to this claim in "Analysis of 6,515 exomes reveals the recent origin of most human protein-coding variants" http://dx.doi.org...ure11690

"Of the putatively deleterious protein-coding SNVs, 86.4% arose in the last 5,000 to 10,000 years, and they are enriched for mutations of large effect (Supplementary Fig. 14) as selection has not had sufficient time to purge them from the population."

The claim that selection has not had sufficient time to purge the mutations from the population was placed into the context of beneficial mutations via this report: The palaeolithic diet and the unprovable links to our past. http://medicalxpr...nks.html

Excerpt: "Textbook examples include genes associated with lactose tolerance, starch digestion, alcohol metabolism, detoxification of plant food compounds and the metabolism of protein and carbohydrates: all mutations associated with a change in diet."

JVK
Sep 28, 2015
Re:
KYP evolves as a critical immune system to control invading nucleic acids.


Proteins do not evolve. Genes do not evolve. Cell types do not evolve.Species do not evolve.

Control of viruses is nutrient-dependent and the physiology of reproduction links successful control of viruses to biodiversity. Only those who do not understand how nutrient-dependent RNA-mediated gene duplication and RNA-mediated amino acid substitutions link atoms to ecosystems via the organized genomes of all living genera are still claiming that proteins evolve.

And this is extremely remarkable.


When placed into the context of evolution, it is automagical.

This is important on several levels as we and other researchers continue to study this finding," Castillo-González added. "One, to advance science, because we didn't know this kind of mechanism happened.


See for comparison: https://www.youtu...0le52U20

Sep 28, 2015
@JVK

Everyone knows you're a young earth creationist crank, you don't need to keep advertising that fact.

JVK
Sep 28, 2015
Thanks. Have you ever tried to comment intelligently?

All serious scientists know there is only creation and ecological speciation. It occurs because the nutrient-dependent innate immune system protects all cell types in all individuals of all living genera from virus-driven pathology until the time when the immune system is overwhelmed by nutrient stress or social stress.

Excessive stress links immune system suppression to diseases, suffering, and death via altered thermodynamic cycles of protein biosynthesis and degradation, which link viral microRNAs to perturbed protein folding and DNA damage that goes unrepaired by the RNA-mediated events linked to healthy longevity via nutrient-dependent microRNAs.

The fact that I have detailed all this in the context of an atoms to ecosystems model of ecological adaptation does not make me a young earth creationist, and religious beliefs have nothing to do with the topics here.

Proteins do not evolve!

JVK
Sep 28, 2015
Re: Proteins do not evolve!

This is important on several levels as we and other researchers continue to study this finding... because we didn't know this kind of mechanism happened.


This suggests why they believed KYP evolved. No one ever taught them about RNA-mediated amino acid substitutions in the context of cell type differentiation.

If you do not understand how cell type differentiation occurs you might be led to believe that mutations and natural selection lead to the evolution of biodiversity automagically because the molecular mechanisms were missing from what you were taught to believe in.

Many researchers became biologically uninformed science idiots because they believed what they were taught to believe in and never attempted to check for experimental evidence of biologically-based cause and effect that confirmed what they were taught.

Sep 29, 2015
Proteins do not evolve. Genes do not evolve. Cell types do not evolve.Species do not evolve
this comment is called a LIE
it is proven to be such by validated experimental studies, such as:
http://myxo.css.m...dex.html

http://www.extavourlab.com/

Have you ever tried to comment intelligently?
have you? nope. thought not
you are still promoting religion over science
If you do not understand how...
if you don't understand biology and the basic terminology [like the terms used in the lexicon] then why continue to comment?

why share your RELIGION when there is validated science which you ignore?

why continue to post creationist dogma when it is proven to be false and without scientific accuracy?

(rhetorical questions - no need to answer)

oh... almost forgot

reported for pseudoscience

JVK
Sep 29, 2015
http://phys.org/n...ogy.html

The code
is counterintuitive to natural selection.


Accurate representations of biologically-based cause and effect also eliminate mutations and evolution. In less than a month, all neo-Darwinian pseudoscientific nonsense has been eliminated from consideration by serious scientists.

See: Mechanisms of stress in the brain http://dx.doi.org.../nn.4086

See also: Molecular insights into transgenerational non-genetic inheritance of acquired behaviours
http://www.nature...eReviews

Excerpt: Possible mechanisms... during development and adulthood are considered along with...the involvement of epigenetic modifications and non-coding RNAs in male germ cells.

The detailed molecular mechanisms of transgenerational epigenetic inheritance in McEwen et al., can be compared to the possible mechanisms in Bohacek & Mansuy.

Sep 30, 2015
http://phys.org/news/2015-09-physiologists-uncover-code-heart-biology.html

blah blah blah i think it says something that it doesn't say so i will cross post this all over PO...blah blah blah
crossposted in multiple threads and not relevant to most of them, especially in light of your pseudoscience and religious beliefs
reported
also eliminate mutations and evolution
PSEUDOSCIENCE POST with no corroborating evidence

links? references?
supporting documentation?
validation?

IOW- you got nothing so you think linking something and then making a pseudoscience claim to go with it justifies your religion

EPIC FAIL
reported for being a troll, crossposting and pseudoscience

JVK
Sep 30, 2015
Re: The detailed molecular mechanisms of transgenerational epigenetic inheritance in McEwen et al., can be compared to the possible mechanisms in Bohacek & Mansuy.

See also: Understanding the bases of sex differences http://www.ncbi.n.../7209509

"The articles in this issue summarize the factors surrounding sex differences with respect to ontogeny, phenotype, and hormone-sensitive actions. They follow a sequence that begins with genetic sex differences and carries through to cell, tissue, organ and, finally, systemic effects of gender."

The gene-cell-tissue-organ-organ system pathway is RNA-mediated and it links the epigenetic landscape to the physical landscape of DNA in all living genera via the biophysically constrained chemistry of nutrient-dependent protein folding and physiology of reproduction.

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