Researchers Discover How Plants Reprogram Their Cells To Fight Invaders

Factories can retool to support the demands of conflict during times of war. Assembly lines switch from producing washing machines to aircraft engines, or from creating vehicle parts to machine guns.

According to Xinnian Dong, a professor at Duke University, plants can also change their production from peacetime to wartime.

Microbes, such as bacteria, viruses, and other pathogens, frequently damage crops and other plants. A plant modifies the chemical stew of proteins, the life's mainstay components, inside its cells when it detects a microbial incursion.

Dong and her research team have been piecing together how they accomplish it over the past few years. Dong and lead author Jinlong Wang describe the essential elements in plant cells that reconfigure their protein-making machinery to fight disease in a new study that was just published in the journal Cell.

Bacterial and fungal diseases reduce crop productivity by about 15% annually, costing the world economy over $220 billion. For defense, plants rely on their immune system.

Plants lack specialized immune cells that can circulate through the circulation to the site of infection, in contrast to animals. Instead, every cell in the plant must be capable of standing and engaging in combat to defend itself.

Plants change their focus from growth to defense when they are under threat. In other words, cells begin synthesising new proteins while reducing the production of existing ones. Then, according to Dong, "everything get back to normal within two to three hours."                                                                                             

The tens of thousands of proteins that are produced by cells perform a variety of functions, including catalyzing processes, identifying foreign molecules, acting as chemical messengers, and transporting materials in and out. Genetic instructions contained in the DNA crammed inside the cell's nucleus are translated into a messenger molecule called mRNA in order to make a certain protein. This strand of mRNA then moves out into the cytoplasm, where a structure called a ribosome “reads” the message and transforms it into a protein.

In a 2017 study, Dong and her team discovered that some mRNA molecules translate into proteins more quickly than others when a plant is infected. The researchers found that these mRNA molecules share a region at the beginning of the RNA strand with repeating letters in its genetic code, where the nucleotide bases adenine and guanine repeatedly repeat themselves.

The recent study by Dong, Wang, and colleagues demonstrates how this region cooperates with other cellular structures to stimulate the synthesis of "wartime" proteins.

They showed that plants' ability to detect pathogen attacks results in the removal of molecular signposts that normally direct ribosomes to land on and begin reading the mRNA, preventing the cell from producing its typical "peacetime" proteins.

Instead, ribosomes use the region of recurrent As and Gs within the RNA molecule for docking and start reading from there. This circumvents the standard starting point for translation.

According to Dong, plants must strike a balance when battling infection. Less resources are available for photosynthesis and other life-sustaining processes when more resources are dedicated to defense. Collateral damage can be caused if defense proteins are produced in excess. Plants with an overly active immune system, for instance, grow stunted.

Researchers want to develop new strategies for engineering disease-resistant crops without reducing output by better understanding how plants achieve this equilibrium, according to Dong.

The majority of Dong's research team's tests were conducted on the mustard-like plant Arabidopsis thaliana. However, comparable mRNA sequences have been discovered in a variety of different taxa, such as fruit flies, mice, and humans, suggesting that they may have a wider impact on the regulation of protein synthesis in both plants and animals, according to Dong.

By DUKE UNIVERSITY