Canadian-led study will help scientists identify key genomic regions in canola, other food plants

TORONTO,ON What allows certain plants to survive freezing and thrive in the Canadianclimate, while others are sensitive to the slightest drop in temperature? Thosethat flourish activatespecific genes at just the right time but the waygene activation is controlled remains poorly understood.

Amajor step forward in understanding this process lies in a genomic map producedby an international consortium led by scientists from the University of Toronto(U of T) and McGillUniversity and published online today in the journalNature Genetics.

Themap, which is the first of its kind in plants, will help scientists to localizeregulatory regions in the genomes of crop species such as canola, a major cropin Canada, according to researcherswho worked on the project. The team hassequenced the genomes of several crucifers (a large plant family that includesa number of other food crops) and analyzed them along with previouslypublishedgenomes to map more than 90,000 genomic regions that have been highly conservedbut that do not appear to encode proteins.

Plants are complicated organisms, and they have many types of cells and structures, said Dr. Annabelle Haudry, one of the studys lead authors and former U of T postdoctoral fellow. We found that genes involved in defining how these cells and structures grow as the plant develops from a seed and how it responds to environments stimuli are surrounded by many of these switches.

Amazingly,similar organization of switches was found for the genes that control earlyhuman development from an embryo an example of convergent evolution, saysRobert Williamson, Uof T PhD student and study coauthor. (Convergent evolutionis the scientific term for biological traits that arrive through differentevolutionary lineages.) Work is currently underway toidentify which of thoseregions may be involved in controlling traits of particular importance tofarmers.

Thestudy also weighs in on a major debate among biologists, concerning how much ofan organisms genome has important functions in a cell, and how much is junkDNA, merely along forthe ride, says U of Ts Professor Alan Moses, also involved in the study. While stretches of the genome that code for proteins arerelatively easy to identify, many other noncoding regionsmay be importantfor regulating genes, activating them in the right tissue and under the rightconditions.

Whilehumans and plants have very similar numbers of protein-coding genes, the mappublished inNature Geneticsfurthersuggests that the regulatory sequences controlling plant genes are farsimpler,with a level of complexity between that of fungi and microscopic worms. Plantsseem to have a large fraction of their genome that is junk DNA, says U of TsProfessor StephenWright, another leader of the study. But our analysis allowsfor identification of the tens of thousands of needles in the haystack thatare important for gene regulation.

Fundingfor the research was provided by Genome Canada and Gnome Qubec, along withthe European Regional Development Fund, the Czech Science Foundation, and theNational ScienceFoundation.

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A genomic atlas of gene switches in plants provides a roadmap for crop research - Canadian-led study will help ...

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