Phenotypic Novelty And Transpositional Activation Of Multiple Mobile Elements In An Extremely Remote Plant Hybridization Cross Between A Monocot, Rice (Oryza Sativa L.), And A Dicot, Oenothera Biennis L.

Inter-species hybridization is prevalent in plants, however, it is not known if unsuccessful or"aborted"hybridizations will impose any genetic effects on the recipient genome. In this communication, we report that artificial pollination of a monocot plant, rice (Oryza sativa L.), by pollens of a dicot plant, evenning primrose (Oenothera biennis L.), produced a variant rice individual (named Tong-211mut-1) with striking, heritable phenotypic variations in multiple morphological traits, including flowering time, panicle-size, seed-size and kernel pigmentation. Molecular characterization of Tong-211mut-1 and its selfed progenies revealed mobilization of several previously characterized transposable elements, including the MITE mPing and three long-terminal repeat (LTR) retrotransposons, Osr7, Tos17 and Osr23, and the destabilized state of these elements were meiotically heritable. Genome-wide analysis by the AFLP and MSAP markers on S0 and S1 plants of Tong-211mut-1indicated the occurrence of both genetic mutation and cytosine methylation alteration at multiple genomic loci, with transgenerational instability being prevalent. Given simplicity of this cross-pollination experiment, it can be envisioned that similar incidents may occur under natural conditions. Thus, our results may implicate another role of hybridization in plant evolution, namely,"accidental"cross-pollinationby a certain unrelated species may be stochastically mutagenic and elicit rampant genetic and epigenetic instabilities, which may be subject to natural selection and contribute to changes in gene expression and phenotypes.