Like animals, plants constantly face attacks from viruses, bacteria, fungi, and insects during their growth. Although plants cannot move to avoid these threats like animals do, they are not defenseless. Through millions of years of evolution, plants have developed sophisticated immune systems to fight back against these invaders.
Let's examine how bacteria invade plants. Pathogenic bacteria can enter plant leaves through tiny openings called stomata on the leaf surface. Once inside, they move through intercellular spaces between plant cells, where they steal nutrients and multiply rapidly, causing damage to the plant tissue.
Plants are not defenseless against bacterial attacks. Plant cell surfaces are equipped with many receptor proteins that form the first line of defense. These receptors can recognize specific molecules from pathogens and immediately activate the cell's internal defense systems to fight against the bacterial invasion.
However, cunning bacteria fight back by secreting toxic proteins into plant cells. These toxins use special chemical reactions to precisely destroy key proteins in the plant's defense system. But plants have become even more sophisticated through long evolutionary battles, developing a second line of defense composed of resistance proteins and decoy proteins to trick the bacterial toxins.
Scientists from Tsinghua University and the Chinese Academy of Sciences discovered that when toxic proteins destroy decoy proteins, the damaged decoy proteins cause resistance proteins to undergo a series of conformational changes and assemble into a protein machine called a resistosome. The resistosome can reactivate defense systems and send suicide signals to the cell membrane, causing infected plant cells to sacrifice themselves along with the bacteria, thereby protecting other healthy cells. These discoveries help us better design disease-resistant crops and reduce pesticide use to protect the environment.