Molecular evolution and selection of a gene encoding two tandem microRNAs in rice.

It has been shown that overexpression of MIR156b/c resulted in a bushy phenotype in maize and rice. Our results indicated that the MIR156b/c locus was highly conserved among cereals, but not in dicots and that genome duplication events played an important role in the evolution of the miR156 family. Genetic diversity investigation at the locus indicated that only approximately 9% of nucleotide diversity observed in wild rice (O. rufigogon) was maintained in the cultivated rice and the neutral model was rejected (P<0.05) based on Tajima's D and Fu and Li's D( *) and F( *) tests. To our knowledge, this is the first example of miRNA gene to be targeted by both natural and domestication selection in plants.