Genome-wide study shows evidence of genetic selection
One aspect of the climate change models researchers have been developing looks at how plant ranges might shift, and how factors such as temperature, water availability, and light levels might come into play. Forests creeping steadily north and becoming established in the thawing Arctic is just one of the predicted effects of rising global temperatures.
A recent study published online August 24, 2014 in Nature Genetics offers a more in-depth, population-based approach to identifying such mechanisms for adaptation, and describes a method that could be harnessed for developing more accurate predictive climate change models. For the U.S. Department of Energy, which is developing biomass crops for biofuels production, this knowledge could determine which genotypes – genetic makeup of an organism – of biomass crop may thrive better than others in certain environments. The team led by Gerald Tuskan of Oak Ridge National Laboratory (ORNL), the Department of Energy Joint Genome Institute (DOE JGI) – a DOE Office of Science user facility – and Stephen DiFazio of West Virginia University, used a combination of genome-wide selection scans and analyses to understand the processes involved in shaping the genetic variation of natural poplar (Populus trichocarpa) populations.
As part of this long-term study, the team took samples from 1,100 poplar trees growing in wild populations in California, Oregon, Washington and British Columbia. They then clonally propagated (through cuttings) these trees in three plantations in California and Oregon. For their analyses, they pared the group down to 544 unrelated individuals whose genotypes could be accurately determined so as to characterize the genetic basis for variation in adaptation. The shift from an approach focused on single candidate genes to the large-scale computational approach analyzing all of them is made possible by the availability of the poplar genome, which was published in the journal Science in 2006 by the DOE JGI. Since the genome was made publicly available, it has been used to understand woody perennial plant development and served as a model for genome-level insights in forest trees. The publication itself has been cited more than 1,000 times in a wide variety of journals.
"This is the first time that deep genomics resources have ever been applied to an ecological question, in this case: 'What does selection do at the genome level?'" said Tuskan. "In the past, people looked at adaptation to factors such as temperature and light levels, and they examined variation in those genes as they vary across environmental gradients. There was a preconceived notion and a very narrow view of what was causing the response. Here, we took five major approaches, applied them blindly to the whole genome, and let the analysis show us where the fingerprints of selection are and what genes fall under those fingerprints." Watch a video of Tuskan on the importance of selection in trees at http://bit.ly/Tuskan14fingerprints.
Going from 1,000 genotypes and 45,000 genes "to figuring out what's not just statistically significant but biologically meaningful" wasn't easy, said study first author Luke Evans of West Virginia University. "We did it by determining selection targets – things that looked like they might be under natural selection in wild populations and looked at growth and performance evidence that they affect adaptive traits. If these targets showed not only computational evidence of selection but also influenced phenotypes, it was a nice sort of dovetailing that was mutually supportive."
DiFazio highlighted the significance of the computational work. "Our approach is particularly powerful because we are mining standing natural variation resulting from tens of thousands of years of evolution and selection such that the alleles or gene variants that we have identified have great promise to provide robust, long-term improvements to biofuel feedstocks."
Evans also noted that their study yielded nearly 18 million single base pair variants of DNA sequence (called "SNPs") in poplar. These data can be accessed at Phytozome, DOE JGI's plant comparative genomics portal. "That's a massive number of naturally occurring variants, a lot in cell wall chemistry genes and other known productivity genes. This provides an immediate resource for tree breeding programs," he said.
The team identified 397 genomic regions that contribute to adaptive traits for wild populations of poplars. For example, data gathered on height, spring bud flush and fall bud set from the clonally-replicated poplars growing in three plantations indicated that in warmer climates, trees with earlier bud flush and later bud set were favored.
Given the importance of poplar trees, not just for their role in the ecosystem, for instance, in capturing carbon, but also for their economic importance in fields ranging from timber to bioenergy, Evans noted that the ability to have plantations of poplars through vegetative propagation is a significant tree-breeding tool for picking the appropriate stocks for the task. "If you know every base in a genome, you can skip whole generations and use genomic information to predict how well an individual will do," he said. "Plantations serve as the initial tests where you can take that genomic information and calibrate those predictions. With those reference points, you can scale everything."
Aside from Evans, Tuskan, and DiFazio, other authors on the study were Gancho Slavov of Aberystwyth University, UK; Eli Rodgers-Melnick of West Virginia University, Joel Martin and Wendy Schackwitz of the DOE JGI; Priya Ranjan, Wellington Muchero, Lee Gunter, Jin-Gui Chen of ORNL; and Amy Brunner of Virginia Tech.
Members of the BioEnergy Science Center (BESC), a U.S. DOE Bioenergy Research Center supported by the Office of Biological and Environmental Research in the DOE Office of Science, contributed to the published work, in particular the collection, propagation, and maintenance of the common gardens.
The U.S. Department of Energy Joint Genome Institute, supported by the DOE Office of Science, is committed to advancing genomics in support of DOE missions related to clean energy generation and environmental characterization and cleanup. DOE JGI, headquartered in Walnut Creek, Calif., provides integrated high-throughput sequencing and computational analysis that enable systems-based scientific approaches to these challenges. Follow @doe_jgi on Twitter.
DOE's Office of Science is the largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
David Gilbert | Eurek Alert!
Zebrafish's near 360 degree UV-vision knocks stripes off Google Street View
22.06.2018 | University of Sussex
New cellular pathway helps explain how inflammation leads to artery disease
22.06.2018 | Cedars-Sinai Medical Center
In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.
Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
22.06.2018 | Materials Sciences
22.06.2018 | Earth Sciences
22.06.2018 | Life Sciences