A change of ploidy can modify epigenetic silencing

• Published in: Proceedings of the National Academy of Sciences - PNAS 1996-07, Vol.93 (14), p.7114-7119
• Main Authors: Scheid, O.M. (Tomiyazev Institute of Plant Physiology, Moscow, Russia.), Jakovleva, L, Afsar, K, Maluszynska, J, Paszkowski, J
• Format: Article
• Language: English
• Subjects: Alleles; ANTIBIOTICOS; ANTIBIOTIQUE; Arabidopsis - genetics; Arabidopsis - physiology; ARABIDOPSIS THALIANA; ARN; Base Sequence; Blotting, Northern; Caulimovirus - genetics; Cinnamates; Crosses, Genetic; DIPLOIDIA; DIPLOIDIE; Diploidy; DNA Primers; Epigenetics; EXPRESION GENICA; EXPRESSION DES GENES; FOSFOTRASFERASA; GENE; GENES; GENETICA; Genetics; GENETIQUE; Hybridity; Hygromycin B - analogs & derivatives; Hygromycin B - pharmacology; MEDICAMENT; MEDICAMENTOS; Molecular Sequence Data; PHOSPHOTRANSFERASE; Phosphotransferases (Alcohol Group Acceptor) - biosynthesis; Phosphotransferases (Alcohol Group Acceptor) - genetics; PLANTAS TRANSGENICAS; PLANTE TRANSGENIQUE; Plants, Genetically Modified; Ploidies; Polymerase Chain Reaction; Polyploidy; Promoter Regions, Genetic; Recombinant Fusion Proteins - biosynthesis; RESISTANCE AUX PRODUITS CHIMIQUES; RESISTENCIA A PRODUCTOS QUIMICOS; RNA, Ribosomal - biosynthesis; Seedlings; TETRAPLOIDIA; TETRAPLOIDIE; Tetraploidy; Transgenes; TRIPLOIDIA; TRIPLOIDIE; Triploidy
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.93.14.7114

A silent transgene in Arabidopsis thaliana was reactivated in an outcross but not upon selfing of hemizygous plants. This result could only be explained by assuming a genetic difference between the transgene-free gametes of the wild-type and hemizygous transgenic plants, respectively, and led to the discovery of ploidy differences between the parental plants. To investigate whether a change of ploidy by itself can indeed influence gene expression, we performed crosses of diploid or tetraploid plants with a strain containing a single copy of a transgenic resistance gene in an active state. We observed reduced gene expression of the transgene in triploid compared with diploid hybrids. This led to loss of the resistant phenotype at various stages of seedling development in part of the population. The gene inactivation was reversible. Thus, an increased number of chromosomes can result in a new type of epigenetic gene inactivation, creating differences in gene expression patterns. We discuss the possible impact of this finding for genetic diploidization in the light of widespread, naturally occurring polyploidy and polysomaty in plants.