Effects of Aneuploidy on Genome Structure Expression and Interphase Organization in Arabidopsis thaliana

Abstract:  Aneuploidy refers to losses and/or gains of individual chromosomes from the normal chromosome set. The resulting gene dosage imbalance has a noticeable affect on the phenotype, as illustrated by aneuploid syndromes, including Down syndrome in humans, and by human solid tumor cells, which are highly aneuploid. Although the phenotypic manifestations of aneuploidy are usually apparent, information about the underlying alterations in structure, expression, and interphase organization of unbalanced chromosome sets is still sparse. Plants generally tolerate aneuploidy better than animals, and, through colchicine treatment and breeding strategies, it is possible to obtain inbred sibling plants with different numbers of chromosomes. This possibility, combined with the genetic and genomics tools available for Arabidopsis thaliana, provides a powerful means to assess systematically the molecular and cytological consequences of aberrant numbers of specific chromosomes. Here, it is reported on the generation of Arabidopsis plants in which chromosome five is present in triplicate. We compare the global transcript profiles of normal diploids and chromosome five trisomics, and assess genome integrity using array comparative genome hybridization. Live cell imaging are used to determine the interphase 3D arrangement of transgene-encoded fluorescent tags on chromosome five in trisomic and triploid plants. The results indicate that trisomy five disrupts gene expression throughout the genome and supports the production and/or retention of truncated copies of chromosome five. Although trisomy five does not grossly distort the interphase arrangement of fluorescent-tagged sites on chromosome five, it may somewhat enhance associations between transgene alleles. Our analysis reveals the complex genomic changes that can occur in aneuploids and underscores the importance of using multiple experimental approaches to investigate how chromosome numerical changes condition abnormal phenotypes and progressive genome instability. Ci tation: Huettel B, Kreil DP, Matzke M, Matzke AJM (2008) Effects of Aneuploidy on Genome Structure, Expression, and Interphase Organization in Arabidopsis thaliana. PLoS Genet 4(10): e1000226. doi:10.1371/journal. pgen.1000226