(Image credit: Andrey Zhuravlev)

Have you ever wondered about the plant immune system? If plants can’t move and get away from pathogens like animals can, how do they fight disease? The answer is a combination of strategies that recognize microbes, compartmentalize infection, boost immunity, and increase disease resistance. 

Do Plants Have Immune Systems? 

Plants do have an immune system that both differs from and is similar to the human immune system. Both can fight off an infection and have similar signaling pathways and related compounds, but plants use different mechanisms. 

Plant immunity is not adaptive like human immune systems. It doesn’t remember specific pathogens in order to mount a targeted defense the next time around. Instead, it deploys more general strategies for fighting off pathogens. Both plants and animals have mechanisms for recognizing and acting against the proteins that pathogens release into host cells. 

Types of Plant Immune Responses 

The immune response in plants is varied but also generalized. Researchers have found several strategies plants use to mount a defense in the phase of disease: 

  • Two lines of defense. Plants have a double line of defense against disease. The first consists of receptors on the surface of cells that detect pathogens. This triggers an alarm that helps cells recognize the infectious proteins that would like to turn of the cell’s defense system. Scientists are just beginning to understand the structure of receptors that identify infecting pathogens and what happens next. 
  • Phase separation. Researchers recently discovered a mechanism by which plants compartmentalize immunity. Plants react to pathogens by using immune proteins to create a gel in certain areas of the cells. Inside the nucleus, these gel-like components protect the plant’s genome. 
  • Sacrificing healthy tissue. Plants have an advantage over humans in using this strategy. They can sacrifice part of leaf tissue to infection to save the rest of the plant. Scientists found an enzyme that lowers the plant’s resistance to infection. The plant deploys this to create a barrier of dead cells around an infected spot. 
  • Symbiosis. Some microbes are beneficial to plants and help them fight off disease. A study of corn found that fungi in the soil and on the roots boost immunity in the plant. The mechanism is chemically complex and still under study. 

Immunity in plants is a fascinating topic that scientists are understanding better every day. It’s important for fighting disease in crops in particular, but much of plant immunity remains a mystery.

Mary Ellen Ellis

Mary Ellen Ellis has been gardening for over 20 years. With degrees in Chemistry and Biology, Mary Ellen's specialties are flowers, native plants, and herbs.