The Preliminary Studies On Transgenic Indica Rice Of Two Relative Starch Synthesizing Genes Obtained And Their Descendants

Starch makes up about 90% dry matter content of milled rice , which is divided into amylose and amylopectin . It proved that its molecular structure and proportion has influenced the rice quality of cooking and eating. At present, The quality of Indica hybrid rice is poor, As it is mainly induced by high amylose of sterile lines , people hoped to improve rice quality by decreasing their amylose content . But it is difficulty to get the purpose by traditional genetic improvement because of endosperm characteristic of amylose . At now , it has led low breeding efficiency on rice quality improvement.With quick development of the biology molecular and the gene engineering of starch , It is a new research direction improving rice quality by gene enginering . In this paper , Soluble starch synthase enzyme gene and starch branching enzyme gene have been introduced into rice restoring line Minhui86 (Indica Saliva L. ) by Agrobacterium-mediated transformation , Studies on change regulation of amylose content of transpenic rice . We preliminary have built the breeding system of gene engineering on rice quality improvement . This result was summarized as following :1.Forward expression structure of soluble starch synthase gene and forward or reverse expression structure of starch branching enzyme gene were introduced into rice restoring line Minhui86 (.Indica Saliva L . ) by Agrobacterium-mediated transformation . We have totally obtained 187 independent transgenic plants .2.PCR and Southern blot showed that forward expression structure of soluble starch synthase gene and forward or reverse expression structure of starch branching enzyme genes have been integrated into rice genome.3.Genetic analysis and ^detecting showed that the majority of T] generation (Tn selfed seed) accorded with Mendelian segregation (3:1) , the genes could inherit into its descendances as single gene .and could get pure independent plants at T3 generation (T1 selfed seed).4.Fourteen pure independent plants of soluble starch synthase gene of T4 generation (T3 selfed seed) and thirteen pure independent plants of starch branching enzyme gene of T2 generation (Ti selfed seed) have been obtained now. Some pure transgenic lines have hybrided by 6 sterile lines .5.Amylose content analysis showed that the quantity of amylose of the transgenic lines of forward expression structure of soluble starch synthase gene has reduced markedly compared to the original species , 13.3 % decreasing rate on average , the biggest decreasing rate arrived 31.5% . The quantity of amylose of he transgenic lines of forward expression structure of starch branching enzyme gene has also reduced compared to the original species , 10.4 % decreasing rate on average , the biggest decreasing rate arrived 24.2% . While the quantity of amylose of the transgenic lines of reverse expression structure of starch branching enzyme gene has increased 8.6 % on average , the biggest amylose content of the lines was 19.7 , increasing 21.6 % compared to the original species.we havel discussed some questions , such as the feasibility of improving rice quality by gene engineering and change of transparency and shape of partial transgenic plants .