It’s hard life being a plant! From pathogens and herbivores to unfavourable weather, they are constantly injured or wounded and their sessile lifestyle only adds to the trouble. Despite all this, they heal and survive. How did they evolve such a great repair mechanism? What are the molecules and proteins aiding it? These were some of the questions an international team of researchers set out to answer and have now found some interesting mechanisms.
Ability to repair
A paper recently published in Development shows that a protein named PLETHORA (PLT), which encodes stem cell promoting factors, helps in the regeneration of the vascular system at the site of injury. This protein binds to and activates the expression of another gene (CUC2). These two together increase the production of a plant growth hormone called auxin at the wound site. The combination of these proteins and hormones gives the plant the ability to repair wounds.
The corresponding author of the paper Kalika Prasad explains that the work spanned nearly a decade to create the right set of injuries mimicking those that plants encounter throughout their life and then hunt for the plant proteins that help in this essential quick fix. He is from the School of Biology at the Indian Institute of Science Education and Research at Thiruvananthapuram (IISER-Tvm).
“Though it was known that plants communicate within their different parts and with other plants during injury, not much was known about how they handle the injury. Though we carried out the initial studies on the roadside mustard plant, we noticed similar results when tested the using rice PLT protein too,” he adds.
It was seen that the injury healed not just at the surface but the veins regenerated too. “There was proliferation of the epithelial cells to seal the wounds and also functional restoration of tissue cells. The vein regeneration is very essential as transport of food, hormone, water, happens through it and any disruption may further hinder the plant growth,” explains Dhanya Radhakrishnan, PhD scholar and first author of the paper from IISER-Tvm.
Another interesting find was that these two proteins did not play any role in the general development of vascular system but stepped into action only during its injury.
“We were able to set up a mathematical model that gave us guidance that as the size of the wound changes the nature of the repair changes. The numerical simulations showed that after a particular size injury, the plant will be unable to regenerate or heal,” adds Anil Shaji from the Department of Physics at IISER-Tvm. He is one of the authors of the papers and has set out to uncover the physical processes like the flow of hormones that are involved in this healing process.
“We are now trying to find out all the different genes and pathways involved in the healing process and also the cellular reprogramming events. To decode if the day–night conditions affect this process would also be interesting,” adds Anju P.S., a research scholar and one of the first authors of the paper from the institute. The researchers hope that in the future these genes can be produced in surplus to create plants that can withstand insect attack and other injuries.