Plants are incredibly temperature sensitive and can perceive changes of as little as one degree Celsius. Now, a report in the January 8th issue of the journal Cell, a Cell Press publication, shows how they not only 'feel' the temperature rise, but also coordinate an appropriate response -- activating hundreds of genes and deactivating others; it turns out it's all about the way that their DNA is packaged.
The findings may help to explain how plants will respond in the face of climate change and offer scientists new leads in the quest to create crop plants better able to withstand high temperature stress, the researchers say.
"We've uncovered a master regulator of the entire temperature transcriptome," said Philip Wigge of John Innes Centre in the United Kingdom in reference to the thousands of genes that are differentially activated under warmer versus cooler conditions.
Using the model plant Arabidopsis thaliana the researchers show that a key ingredient for plants' temperature sensing ability is a specialized histone protein, dubbed H2A.Z, that wraps DNA into a more tightly packed structure known as a nucleosome. Wigge likens nucleosomes to compact balls of string. As temperatures rise, H2A.Z histones allow DNA to progressively unwrap, leading nucleosomes to loosen up, they show.
"When it gets warmer, the DNA unwraps," he said, which allows some genes to switch on and others to switch off. They aren't yet sure exactly how all that happens, but Wigge suspects the altered nucleosome structure gives access to sites on the DNA where activators of some genes can bind along with repressors of other genes.
"In addition to H2A.Z containing nucleosomes having more tightly wrapped DNA, our results suggest that the degree of unwrapping may also be responsive to temperature," the researchers wrote. "This result suggests a direct mechanism by which temperature may influence gene expression, since it has been sh
|Contact: Cathleen Genova|