WEST LAFAYETTE, Ind. - Hybrid plants with multiple genome copies show evidence of preferential treatment of the genes from one ancient parent over the genes of the other parent, even to the point where some of the unfavored genes eventually are deleted.
Brian Dilkes, an assistant professor of genetics at Purdue University, worked with a team of scientists at the University of California Davis and University of Southern California to study the genome of Arabidopsis suecica, a hybrid species with four chromosome sets formed tens of thousands of years ago from a cross between Arabidopsis arenosa and Arabidopsis thaliana, a plant commonly used in laboratories for genetic research. Dilkes said the findings, published in the journal Genome Biology and featured as an editor's choice article in the journal Science, give a glimpse into the evolutionary forces and ultimate fates of genes contributed by the two parents to a hybrid
"There often is no visible signature of these genes when we look at the plants with a microscope, but we can still observe those genes in the genome sequence," Dilkes said. "Moreover, the ability to make crosses between Arabidopsis thaliana and Arabidopsis arenosa gives us the opportunity to compare laboratory-derived plants that were generated yesterday with naturally occurring species from the wild and compare the two kinds of species hybrids. This is essentially allowing us an opportunity to 'replay the evolutionary tape,' in the words of Stephen J. Gould."
The researchers compared the genomes and gene expression among Arabidopsis suecica plants that have evolved over tens of thousands of years to similar species of hybrids made in the lab from fresh crosses.
When the contribution of genes from each parent was compared, they were not equal. One parent's genes were preferentially expressed at higher levels. In the cases where that happened, it was three times more likely that the prefere
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