“Aberrant” plants in cauliflower: 2. Aneuploidy and global DNA methylation

Abstract

Aberrant phenotypes of cauliflower were detected throughout the cultivation period and in any variety type. The rate of these phenotypes in the field has recently increased. We reported previously on the first part of our results which showed that (1) the rate of aberrant plants varied with genotype and cultivation area, (2) the aberrant phenotypes can evolve or reverse to normality during the plant cycle and (3) the capacity to express a variant phenotype can be transmitted to the progeny. An epigenetic hypothesis has been proposed to explain the determinism of the phenomenon. Further investigation on the “aberrant” character focussed on the flow cytometric estimation of ploidy levels and on the parallel observation of meiosis. Only a fraction of aberrant plants did show aneuploidy and various ploidy levels were found for the same phenotype. Indeed, aneuploidy could not be related to the aberrant phenotype although it could probably be a consequence of the aberration phenomenon. HPLC analysis of global DNA methylation rates showed that DNA hypermethylation occurred in plants which exhibited an evolution of their phenotype during vegetative cycle. The epigenetic origin of aberrant phenotypes in cauliflower is discussed with reference to epigenetic diseases described in human beings.