| Inter-species hybridization is prevalent in plants. It plays an important role for genomic evolution. It's a traumatic experience to the plant genome, under which broad genetic and epigenetic variation could be caused. It is notable that more often than not investigators have been focusing only on the progenies holding the characters from both parents, and therefore, we have no idea whether remote-hybridizations may also cause a kind of biotic stress to the receptors and cause genome instability. As an attempt to address this problem, we selected 10 progenies of a remote-hybridization cross between rice cv."Tong-313"and an accession of Eulaliopsis binata as experimental materials, which have striking phenotypic variations in multiple morphological traits, including seed-size, kernel pigmentation, arista-length, and certain agronomic traits. Molecular characterization of"Tong-313"and its selfed progenies revealed mobilization of several previously characterized transposable elements, including the MITE mPing and a long-terminal repeat (LTR) retrotransposons Tos17. Genome-wide analysis by the MSAP markers on F2 plants of"Tong-313"indicated the occurrence of cytosine methylation alteration at multiple genomic loci. 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-pollination by 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.
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