Abstract
The MET1(Methyltransferase1) gene copies the pattern of cytosine methylation at CpG sites to the newly synthesized strand, which plays a critical role in epigenetic inheritance. While Arabidopsis carries the single MET1 gene, it is known that rice bears two redundant MET1 genes, OsMET1a and OsMET1b. We have developed an efficient and generally applicable gene targeting (GT) procedure in rice, which is based on a strong positive-negative selection in a large-scale Agrobacterium-mediated transformation, followed by PCR screening. To elucidate the function of rice MET1 genes, we are attempting to isolate transgenic rice plants having the GUS reporter gene fused with the endogenous promoters of these OsMET1 genes by GT. We have obtained 15 and 3 independent transformed lines with OsMET1a and OsMET1b modified in the heterozygous condition. We will discuss the results obtained from the OsMET1 knock-in mutants and technological aspects of our knock-in targeting.
