The use of molecular information for plant breeding

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The objectives of the present study is to select and create new genes by means of molecular approaches in rice. Firstly, the experiments were carried out regarding the diversification of cis-acting elements of the Wx gene whose expressions have a role for eating quality. By comparing DNA sequences and recombination frequency, it was found that the region in the Wx gone is recombinationally active and it is possible to recombine different cis-acting elements which are present among rice cultivars. Secondly, the experiments were carried out to induce trans-acting mutant genes. The Wx gene expression is enhanced by cool temperatures during the grain-filling period, causing unfavorable eating quality of rice. A leaky wx mutant were used to screen temperature-insensitive mutations after EMS treatments since the increment of amylose was visually detected under low temperatures. A mutant line was proved by western blotting analysis to be temperature-insensitive regarding the Wx expression. The present results revealed that this mutant is useful for stable eating quality of rice. Since the transfer of the mutant into rice cultivars is not easy, it is suggested that mutation breeding of rice lines carrying the leaky phenotype could be more practical for its prompt use.