Transferring Of Soybean Glycinin Gene Into Rice

Rice and soybean grains are major sources of nutrition for humans, cattle and other animals. However, simultaneous consumption of rice and soybean grains is necessary to complement the proper composition of nessential amino acids for human nutrition. Soybean seeds are deficient in sulfur-containing seential amino acids (Met. Cys), whereas rice has low contents of Lys and Ile. Glycinins are one of the predominant storage proteins of soybean and is important in the functional properties of soybean proteins, which account for 40% of total proteins.The rice glutelins comprise up to 80% of the total seed protein. When viewed nutritionally, these proteins can compensate for one another and collectively provide a better balance of essential amino acids.In addition to their desired physico-chemical properties, e.g. heat -induced gel forming and emulsifying abilities, soybean glycinin lower the cholesterol levels in human serum, while rice glutelins have no significant physicochemical and physiological properties. The traditional breeding appeoach has not been very successful in overcoming the amino acid limitations of rice grains. In addition, these proteins share more than 37% identity in their primary sequences and similar mechanisms in expression, process, accumulation and sorting. Therefore, an alternative approach using genetic engineering for enhancing nutritional value and physicochemical properties of rice seed proteins by introducing the soybean glycinin gene into rice will be possible. Recentlly, biosafety of transgenic crops has been strengthened in these years by fanners and scientists' worldwide.Until now; there was no report about the introduction of soybean glycinin gene into rice elite varieties. So it is necessary to introduce soybean glycinin gene into rice elite varieties and create new marker-free germplasm for breeding. The briefly results are as follows:1. In order to introduce soybean glycinin gene into rice efficiently, two high tissue culture response genotypes were screened by the mature embryo culture from 13 rice elite varieties in total.2. A high efficient system fitting for the target rice varieties was developed by analyzing the influence factors on transferring efficiency during the callus cultivation and Agrobacterium-mediated transformation.MS medium was used for the rice callus induction and subculture.3. The plant binary expression vector PGY-1300(containing soybean glycinin gene), constructed by our lab, was transferred into Agrobacterium tumefaciens LBA4404. The rice calli were transformed by the AgTobacterium tumefaciens -mediated process. The influence factors for Agrobacterium tumefaciens -mediated transformation efficiency and HYG concentration on the efficiency of transformation were discussed .4. 86 independent lines of transgenic japonica rice and 18 lines of indica rice were obtained.Glycinin coding sequence was expressed in transgenic rice plants by PCR analysis. The frequency of gene transferring was 10.1% and 3.52% respectively. The soybean glycinin gene had been integrated into the rice chromosomes in T₁ generational plants and separated in T₁ generational populations.5. Content of protein in T₁ generational rice seeds were analysed using NIR methods, which average increasing rate was 20.18%. It was indicated that soybean glycinin gene was stably inherited.