The serendipitous discovery of a rare mutation and five years of concentrated effort have allowed a team of American and British researchers to define the centromeres of the five chromosomes of Arabidopsis thaliana, a flowering plant that has become the primary model for plant genetics. The centromere is the part of the chromosome that ensures each dividing cell inherits the correct DNA.
The findings, published in the December 24th issue of Science, represent the first time that scientists working with a multi-cellular organism have been able to identify the genetic boundaries of the centromeres -- which are resistant to standard gene mapping techniques -- and to unravel their DNA sequences.
"The centromere is perhaps the most important but also the most inaccessible and the least understood part of a chromosome," said Daphne Preuss, Ph.D., assistant professor of molecular genetics and cell biology at the University of Chicago and leader of the research team.
"Precise mapping of these crucial segments of DNA should shed light on the nature and behavior of chromosomes," said Preuss. "It could help define the centromeres in more complex organisms, boost plant genomics, and speed the development of artificial chromosomes for use in plant engineering," she added. "This now makes Arabidopsis the leading candidate for thorough sequencing of the entire genome in a higher organism."
The Arabidopsis Genome Project hopes to complete sequencing of the first full plant genome by the end of 2000. The sequences of chromosomes
Contact: John Easton
University of Chicago Medical Center