By Jenna Gallegos
Wild plants are really good at surviving extreme temperatures. If we can find out how, we might be able to make our food crops more resilient. A collaborative group of scientists in the United Kingdom recently used an unprecedented approach to study a plant’s response to cold. They found that plants can sense a temperature drop of just two degrees, and they do so in a surprising way.
The cells that make up your brain contain the same genes as the cells that make up your fingernails. When you tan in the summer or a cold breeze draws goosebumps from your arm, your genetic makeup does not change. This is also true of plants.
The pattern of A’s, C’s, G’s, and T’s that makes up the genetic code in a leaf cell is exactly the same as that of a fruit or flower. And plants can’t move to the shade or put on a jacket. That means plants have to extract even more diversity without losing or acquiring new genes. How does this happen?
The answer lies in one of the most foundational tenets of life, the central dogma of biology: DNA is used as a scaffold to make a molecular message called RNA. RNA serves as a template for the construction of proteins.
So each gene is a blueprint, a set of instructions, that can be interpreted many different ways. Depending on the cell, the environment, and even the time of day, a given gene could be used to make many RNA messages or none at all.
The RNA itself is another source of diversity. RNA messages are cut and pasted back together in varying patterns. This process, called alternative splicing, can cause the RNA to trigger production of a different protein or make it unstable, so that it is quickly degraded. RNA can even have a function of its own, acting to destabilize other RNA molecules or cooperating with proteins.
We knew that plants produce a different suite of RNA when the weather turns cold, but we didn’t know to what extent that RNA underwent alternative splicing. A study published recently in The Plant Cell showed that alternative splicing does play a role in cold-response, a big one.
They compared the RNA molecules in plants at normal temperatures with those that had been moved into a room that’s about as cold as a refrigerator. The activity of 9,000 genes differed between the two groups, and, of those, nearly one third were alternatively spliced. The plants also responded to the cold quickly. Alternative splicing took place as soon as 40 minutes and following a drop in temperature of just two degrees Celsius.
These alternative splicing patterns aren’t just an incidental effect of the cold either; they help the plant cope with dropping temperatures. When the researchers mutated one of the genes that is alternatively spliced in response to cold, the mutant plants were less tolerant to low temperatures. That means that alternative splicing helps plants acclimate to the cold.
Intriguingly, cold is likely not the only threat that kick-starts alternative splicing. Alternative splicing could also play a major role in response to pests, drought, or disease. This study provides an important tool to help plant scientists study the role of alternative splicing in all kinds of conditions.
Chemical & Biological Engineering
Colorado State University
Read the research paper on which this story is based:
Christian Calixto, Wenbin Guo, Allan B. James, Nikoleta A. Tzioutziou, Juan Carlos Entizne, Paige E. Panter, Heather Knight, Hugh G. Numo, Runxuan Zhang, John W. S. Brown. (2018). Rapid and dynamic alternative splicing impacts the Arabidopsis cold response transcriptome. Plant Cell Published May, 2018. DOI: https://doi.org/10.1105/tpc.18.00177