A new study used rice seedlings to show that the stress of higher temperatures can trigger a response in the RNA of a plant to control the change in its environment. The stress of higher temperatures can trigger a response in the RNA of a plant or ribonucleic acid, which is part of the genetic messaging system of a cell, to help manage this change in their environment, according to a team of researchers from Penn State. In a study on rice plants, the researchers found that a sudden increase in heat led to changes in the structure of the plant's RNA, which was linked to a loss in the number of its messenger RNAs -- or mRNAs. The mRNA molecule is a particular type of RNA, which transfers DNA instructions to the ribosome in a cell during the protein-making process.

(phys.org)

“Plants cannot regulate their own temperatures, as humans do, or move from the heat source. This process may be one of the ways plants face hot temperatures and drought conditions,” said Sarah M. Assmann, professor of biology at Eberly College of Science. "Rice is a staple food for half the world's population and is particularly important for subsistence agriculture in some parts of the world, so it's a vital food crop," said Assmann. "With climate change and with the goal that we need to increase food production to feed the world's growing population. We are always trying to understand how plants are responding to climate stress, and in the future, we could improve crop varieties, either through breeding or other mechanisms, to get better stress tolerance and better yields."

Although more studies would be needed, this study can serve as an important first step in helping farmers produce more crops resistant to heat and drought, according to the researchers, who announced their findings on November 5 at the Procedures of the National Academy of Sciences.

The researchers looked at more than 14,000 different RNAs to look for changes in the intricately folded structures of molecules that could indicate acute heat stress, said Philip Bevilacqua, Distinguished Professor of Chemistry, Biochemistry and Molecular Biology. In contrast to the entangled double strand or double helix of the DNA molecule, RNA is single-stranded. "Because DNA has two strands, it is really trapped in very few different folds, but RNA, since it's not bound to another strand, can fold back on itself, so there are much more complex wrinkles in the RNA," Bevilacqua said.

To generate heat stress, researchers subjected a group of two-week-old rice seedlings to normal temperatures (108 degrees Fahrenheit) for ten minutes and compared these plants to a control group of plants growing at 72 degrees Fahrenheit. "We chose such a short time because RNA rearrangement is a fast process, while downstream processes such as protein production are slower and we were particularly interested in how RNA is refolded," Bevilacqua said. The researchers found that the wrinkles in the RNA of plants suffering from heat stress are looser than those of the control group. The unfolding of the mRNA then correlated with a loss of the amount of mRNA, suggesting that the unfolding of the mRNA promotes its degradation, a method by which cells regulate which genes.

"This exciting study shows a new level of gene regulation that has not been appreciated so far," said Su. "In particular, we have shown that mRNAs encoding a specific type of regulatory protein, transcription factors, are specifically designed for degradation by unfolding at high temperatures." According to both Bevilacqua and Assmann, studies such as this RNA analysis, which was one of the first to analyze the RNA process in the plant itself or in vivo, could not be performed without the interdisciplinary teamwork of their laboratories. According to Assmann, the laboratories of Bevilacqua and Assmann have been working together for about ten years.

"What I find really interesting about this study is that it includes all the different skills and talents of our labs," said Assmann. "That's what makes science exciting."