Plants, like humans and other animals, have hormones. A role of plant hormones is to perceive problems – be it insect infestation, dryness or extreme heat or cold – and then to signal the rest of the plant that they should react.
A multi-center team led by current and former researchers from the Salk Institute in the United States – including Associate Professor at La Trobe University, Mathew Lewsey – reports new details on how plants respond to a hormone called jasmonic acid or jasmonate.
The results published in Nature Plants show a complex communication network. This knowledge could help researchers develop plants that are harder and more resistant to attack, especially in times of rapid climate change.
“This research gave us a really detailed picture of how this hormone, jasmonic acid, works on many different levels,” said Professor Joseph Ecker, co-corresponding author and researcher at Howard Hughes Medical Institute.
“It enables us to understand how environmental information and development information is processed and how it ensures adequate growth and development,” said Professor Ecker.
The plant used in the study was Arabidopsis thaliana, a small flowering plant from the mustard family. Because of its well-characterized genome, this plant is a popular model system. Scientists can transfer what they learn in A. thaliana to other plants, including those grown for food. Jasmonic acid is not only found in A. thaliana, but in the entire plant kingdom.
“Jasmonic acid is particularly important for a plant’s defense against fungi and insects,” said co-author Dr. Mark Zander, an employee researcher in Ecker’s laboratory. “We wanted to understand exactly what happens when jasmonic acid is perceived by the plant. Which genes are activated and deactivated, which proteins are produced and which factors control these well-coordinated cellular processes? “
The researchers started with plant seeds grown in petri dishes. They kept the seeds in the dark for three days to mimic the first days of a seed’s life when it was still underground. “We know that this phase of growth is very important.”
Dr. Zander said that the first few days in the ground are a challenging time for seedlings as they are exposed to insect and fungal attacks.
“If your seeds do not germinate and successfully emerge from the soil, you will have no harvest,” said Associate Professor Lewsey.
After three days, the plants were exposed to jasmonic acid. The researchers then extracted the DNA and proteins from the plant cells and used specific antibodies against their proteins of interest to determine the exact genomic location of these regulators. Using various calculation approaches, the team was then able to identify genes that are important for the plant’s response to jasmonic acid and also for cellular cross-communication with other plant hormone pathways.
Two genes that became more important system-wide were MYC2 and MYC3. These genes code for proteins that are transcription factors, which means that they regulate the activity of many other genes – or in this case thousands of other genes.
“In the past, the MYC genes and other transcription factors have been studied very linearly,” said Associate Professor Lewsey.
“Scientists are studying how one gene is linked to the next gene and the next, and so on. This method is inherently slow because there are many genes and many connections. We have created a framework here that allows us to analyze many genes at the same time, ”said Associate Professor Lewsey.
“By decrypting all of these gene networks and subnets, we can better understand the architecture of the entire system,” said Dr. Pikeperch.
“We now have this very comprehensive picture of which genes are switched on and off during a plant’s immune response. With the availability of CRISPR gene editing, these details can be useful for growing plants that can better withstand pest attacks, ”said Dr. Pikeperch.
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