Chromosome imbalances lead to predictable plant defects

November 3, 2010, Purdue University
Brian Dilkes was part of a team that determined that plant physical defects can be predicted based on chromosome imbalances. Credit: Purdue Agricultural Communication photo/Tom Campbell

Physical defects in plants can be predicted based on chromosome imbalances, a finding that may shed light on how the addition or deletion of genes and the organization of the genome affects organisms, according to a study involving a Purdue University researcher.

The findings identify easily measured characteristics that vary with imbalances of specific chromosomes, said Brian Dilkes, a Purdue assistant professor of . Understanding why and how those imbalances result in certain characteristics could open the door to correcting those defects in not only plants, but also in animals and humans.

A classic example in humans is in , which is caused by an extra copy of .

"The ability of an organism to replicate and pass on all its genes is incredibly important," Dilkes said. "What we've found is that are sensitive to their dose relative to the rest of the genome. When that balance is disrupted, the organisms fail."

In plants, an imbalance in chromosome number can cause defects in stems, leaves, flowers and other physical features. Understanding how those imbalances cause changes could allow scientists to manipulate plant traits to increase biomass for fuels or other purposes.

"By learning the rules, we can predict the outcome of adding or deleting a gene from an organism," Dilkes said. "We see predictable physical consequences for variation in chromosome dosages. This problem is tractable."

Dilkes, a co-author of the findings released in the early online version of the journal Genetics, was part of a team as a project scientist at the University of California-Davis Genome Center that studied chromosome dosage in the research plant Arabidopsis thaliana. The team used naturally occurring and laboratory-created plants with multiple copies of each chromosome, called polyploids, and then crossed them to create aneuploids, or plants with an irregular number of chromosomes.

The aneuploids, which had either an excess or deficiency of a chromosome, were tested to see which chromosomes were deficient or excessive. Those plants were then phenotyped, recording their physical characteristics. The phenotypes and chromosome imbalances were compared, and it became clear that more or less of particular chromosomes corresponded to specific phenotypic characteristics.

Plants with excess chromosome 1 and a deficiency of chromosome 3 had increased stem diameter, for example. To test the finding, plants were created that had both an excess of chromosome 1 and were deficient in chromosome 3, and stem diameter grew as predicted.

In a surprising turn, the team found that chromosomal imbalance resulted in abnormal traits expressed in its offspring. Plants with a normal number of chromosomes that were descended from plants with chromosome imbalances should have been normal but still displayed abnormal characteristics.

"Something about those chromosomes is different," Dilkes said. "We have no idea what that something is, but it suggests there are multigenerational consequences to changes in chromosome dosage. The DNA sequence says these plants should be perfectly normal, but they are not."

Dilkes said future research would focus on chromosome imbalances in crop such as corn and trying to understand how the excess or deficiency of a gene leads to a particular phenotypic characteristic.

Explore further: Newly-discovered mechanism can explain the Beckwith-Wiedemann syndrome

Related Stories

Hotspots found for chromosome gene swapping

November 29, 2007

Crossovers and double-strand DNA breaks do not occur randomly on yeast chromosomes during meiosis, but are greatly influenced by the proximity of the chromosome’s telomere, according to research in the laboratory of Whitehead ...

X chromosome exposed

May 29, 2008

Researchers from the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, and the EMBL-European Bioinformatics Institute (EMBL-EBI) in Hinxton, UK, have revealed new insights into how sex chromosomes are regulated. ...

Cloning plants from seeds

December 15, 2009

( -- Wageningen geneticists (The Netherlands) are developing a method to replicate the parents of a chosen plant. Known as 'reverse breeding', this will have a big impact for the breeding industry.

Double identities lie behind chromosome disorders

July 8, 2007

Chromosome disorders in sex cells cause infertility, miscarriage and irregular numbers of chromosomes (aneuploidy) in neonates. A new study from Karolinska Institutet published in the scientific journal Nature Genetics shows ...

Recommended for you

Why aren't humans 'knuckle-walkers?'

March 20, 2018

Our closest biological relatives, the African apes, are the only animals that walk on their knuckles; CWRU researchers discovered why

World's last male northern white rhino, Sudan, dies

March 20, 2018

The world's last male northern white rhino, Sudan, has died after "age-related complications," researchers announced Tuesday, saying he "stole the heart of many with his dignity and strength."

Three genes essential for cells to tell time

March 20, 2018

One family of genes allows cells to adapt to daily changes in environmental conditions by adjusting the circadian clock responsible for regular sleep-wake cycles. The new discovery by University of Tokyo scientists reveals ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.