Effective selection and regeneration of transgenic rice plants with mannose as selective agent

A new method for the selection of transgenic rice plants without the use of antibiotics or herbicides has been developed. The phosphomannose isomerase (PMI) gene from Escherichia coli has been cloned and constitutively expres sed in Japonica rice variety TP 309. The PMI gene was transferred to immatu re rice embryos by Agrobacterium-mediated transformation, which allowed the selection of transgenic plants with mannose as selective agent. The integr ation and expression of the transgene was confirmed by Southern and norther n blot analysis and the activity of PMI indirectly proved with the chloroph enol red assay. The results of genetic analysis showed that the transgenes were segregated in a Mendelian fashion in the T-1 generation. The establish ment of this selection system in rice provides an efficient wa for producin g transgenic plants without using antibiotics or herbicides with a transfor mation frequency of up to 41%.