Trees are known to provide oxygen and countless benefits to the environment. However, there are trees like the poplar that emits gases that are worsening air pollution and may alter the climate.
In a journal published in the Proceedings of the National Academy of Sciences, it is stated that poplar populations cover 9.4 million hectares of our planet's surface and this measurement is bigger than the land used 15 years ago. Poplars are quite popular because it is fast-growing and is a source of biofuel as well as a source of fiber for paper and plywood for furniture. Along with plantation plants like palms and eucalyptus, poplars produce isoprene in their leaves as a response to high temperature and drought and this chemical is volatile that millions of metric tons are leaked into the atmosphere annually contributing to greenhouse gas emissions.
HOW DOES ISOPRENE CONTRIBUTE TO GREENHOUSE GAS EMISSIONS?
Isoprene can react with gases that tailpipe pollution which can be a respiratory irritant and it can also produce high levels of aerosol which contributes largely to the cooling effect (reduction of the amount of sunlight that reaches the surface of the planet). Aside from aerosol, isoprene contributes to the global warming potential of methane which, in turn, increases the warming effect.
ADJUSTING THE GENES TO MODIFY POPLAR TREES
Researchers found a way to disable isoprene production in poplars through genetic modification and tested the methodology within three to four years in different plantations in Oregon and Arizona. In their experiment, researchers found out that the genetically modified poplars did not suffer any negative effects during photosynthesis and biomass production. The genetically modified poplars are able to produce cellulose for biofuel and grow the same way as those who still produce isoprene. This is surprising especially since isoprene plays a big role in protecting the plant from stressors brought on by the climate. According to Russell Monson, a professor of ecology and evolutionary biology at the University of Arizona and the lead author of the study, suppressing isoprene production in poplars triggered signaling pathways that compensate for the loss of stress tolerance. "The trees exhibited a clever response that allowed then to work around the loss of isoprene and arrive at the same outcome, effectively tolerating high temperature and drought stress," Monson explains.
Co-author Steven Strauss of Oregon State University states that the study was able to answer the questions regarding the effect of isoprene adjustment in the tree's biomass productivity. The findings of Monson and his team suggest that isoprene emissions can be adjusted without affecting biomass productions and general plant health.
HOW DID THE RESEARCHERS GENETICALLY MODIFY POPLARS
The researchers applied RNA interference to be able to genetically modify poplars because RNA is responsible for the transmission of protein-coding instructions from the DNA of every cell in the tree. The developed genetic tools and protein analyses for this project were developed by scientists at the Institute of Biochemical Plant Pathology at the Helmholtz Research Center in Munich, Germany and they were able to observe changes in the use of biochemical pathways in the organism. Strauss explained that RNA interference is a bit like vaccination which triggers a natural and specific mechanism that suppresses specific targets.
Researchers discovered that the genetically modified poplars were able to adjust easily to the loss of isoprene due to the fact that most plantation growth takes place during the wetter season. Monson explains that the natural cycle of the seasons works in favor of the poplars. The funding of this research project is from the National Science Foundation, the US Department of Agriculture and the German Ministry of Education and Research.
