UBC researchers breeding warrior-dwarf plants to study immune defence

Adriana Suarez-Gonzalez

Plants feed us, give us shelter and clothing, and even provide biofuel. But pathogens are a constant threat, and fungi or bacteria can wipe out entire crops. Xin Li and her team at Michael Smith Laboratories have discovered that plants with an excessive amount of certain immune receptors remain in a constant defence mode, shifting all their resources to fight pathogens while neglecting growth and development. By studying these warrior dwarf plants, researcher may be able to help plants fight back.

What inspired you to study plant immune systems?

I became interested in the arms race between pathogens and plant hosts while studying a pathogenic fungus that infects peanuts. After I completed my PhD, the best plant model to study these questions, called Arabidopsis, was gaining interest in research circles, and I decided to switch focus from the pathogen to the host plant. My background in pathogenesis was definitely an asset. Of course, as an undergrad I didn’t know that was the direction I was going to take, but I just followed my heart along the way.

What is the most commonly used technique in your lab?

Our lab has evolved. At the start we mainly used molecular biology and genetics, but now we're using more biochemistry and genomics. Whenever a new technique is developed, my students are encouraged to try it out. Right now we’re trying to implement a new technique called CRISPR to edit the host plant genome in an effort to understand the function of certain genes. If it works, we could use it to remove important segments of DNA in the host, and then use inoculation experiments (using pathogens) to follow the infection process.

What type of projects are you currently working on?

We study an immune receptor called SNCI1—its main role is to recognize pathogen attacks and trigger a defense response. To understand how the receptor is degraded after pathogen recognition, we engineered plants that express a lot of it. We found that when there is too much SNCI1 plants become dwarves and never leave the battle field—they're in constant defence mode. This is good for the immune response, but bad for growth and development since there is no energy or resources left. So we have seen not only the balance between plant immunity and growth, but we’ve also disentangled some of the steps in the degradation of immune receptors. We found ‘gigantic’ and complex intermediate products, and identified many of their building blocks.

How could this work impact agriculture?

We are currently studying one or two out of many plant immune receptors. I believe that the degradation pathway we've uncovered is rather common, and may be regulating all other plant immune receptors. This information could be beneficial for agriculture and pest control in crop fields. By disturbing the degradation pathway, it could be possible to design chemicals that would make immune receptors more stable when the plants need them the most—when they’re under pathogen attack.