Calcium helps plants defend themselves

Calcium helps strengthen healthy bones and . ensure plant health, according to a new study by Washington State University.

Experiments show that calcium, combined with a protein called calmodulin, causes plants to make salicylic acid (SA) when threatened by infection or other hazards. SA is the close relative of aspirin. In plants, SA acts as a signaling molecule that triggers a series of reactions that help defend against external threats.

The fact that plants produce salicylic acid has been known for hundreds of years, said researcher BW Poovaiah, who is also the research leader, but the role of calcium in stimulating plants to make SA has never been possible. known.

"We began to understand the molecular mechanism involved in calcium / calmodulin stimulating resistance in plants," Poovaiah said .

Poovaiah said that in controlling salicylic acid levels, calcium acts as a 'doorkeeper' inside plant cells, controlling incoming information and helping plants respond to hazards like plague. Common healthy plants have low SA concentrations in cells. This concentration increases when the plant is threatened by an infectious factor or environmental pressure.

Poovaiah explained: 'When we feel dangerous, we often try to avoid it. Plants cannot run anywhere, so they have to activate the internal system to protect themselves. Plants must create different signaling molecules. One of them is salicylic acid '.

Calcium helps strengthen healthy bones and . ensure plant health, according to a new study by Washington State University. (Photo: iStockphoto / Grigory Bibikov)

According to the lead author, Professor Liqun Du, SA creates plant defense methods, such as 'super-sensitive reaction' , in which cells around an infected area die off creating a barrier prevents pathogens from attacking deep inside plants. This mechanism creates protection against immediate risks. SA also activates plant resistance, an immune form that protects plants from pathogen attack.

However, an increase in SA levels also slows the growth of plants, possibly to sustain the battle against germs. This creates a challenging situation for plants - growing faster or better protecting themselves - as well as farmers who can see SA as a tool to protect plants from disease. Translate. Plants with high concentrations of SA will be very safe before infection but grow slowly.Plants that make very little or do not produce SA will grow very fast but are susceptible to infection.

Du said: 'It is a reasonable balance. Too much not too good is not good either. '

Working with the small mustard Arabidopsis thaliana, Poovaiah's team showed that the lock step in this balance is the interaction between calcium / calmodulin and a protein called AtSR1. This protein has the effect of inhibiting the production of salicylic acid. External threats affect calcium in plant cells, and calcium combined with calmodulin stimulates the activity of AtSR1 and SA production.

In environments with few pathogens, a plant has a low SA concentration. Plants remove the defensive barriers and focus on development. If it is infected, SA levels will increase, and plants limit growth to focus on defense.

The important role of AtSR1 is clearly shown in experiments where plants are modified to have more or less AtSR1 than usual. Plants with a lot of AtSR1 have almost no SA. They grow bigger and faster, but are easily infected. Plants that lack the AtSR1 gene have high levels of SA and are always in a defensive state. They are almost uninfected, but are small in size. The same holds true for plants with AtSR1 modified to be unable to combine with calcium / calmodulin, showing the important role of calcium and calmodulin in plants.

Refer:
first. .Calcium / Calmodulin Regulates Salicylic Acid-mediated Response Immune in Plants via AtSR1 / CAMTA3.Nature, Jan 4, 2009 DOI: http://dx.doi.org/10.1038/nature07612