Triple trouble for A. thaliana

A triplet repeat-related genetic defect found in a wild strain of Arabidopsis thaliana could prove to be a simple model for studying these disorders in plants and other organisms.

Sridevi Sureshkumar and colleagues from the University of Queensland and the Max Planck Institute for Developmental Biology in Germany have identified a triplet-repeat associated defect in Arabidopsis that severely impairs leaf growth, particularly in warmer than normal temperatures.

The team studied the wild Bur-0 strain and found a dramatically expanded TTC/GAA repeat in the intron of a gene they have called IIL1, which codes for a chloroplast-localised protein, when compared with the sequenced strain Col-0.

They found that the triplet repeats reduced expression of IIL1, causing a phenotype called ‘irregularly impaired leaves’ (iil), particularly under elevated temperatures.

They also found a wide copy number variability amongst different strains, which is common in humans with triplet expansion disorders. It also often underlies genetic anticipation, in which severity increases with each generation.

Triplet repeat disorders, also known as trinucleotide repeat disorders, in humans include fragile X syndrome, Huntington’s disease and Friedreich’s ataxia.

The researchers conclude that the Bur-0 strain allele presents a simple, or genetically tractable, model for studying triplet repeat disorders.

The team’s research is published online today in Science.