Genetic Trans Of Two Parents Of Indica-hybrid Rices With Two Starchs Synthesis Relevant Genes And The Breeding Utilization

Starch is the major constituent in milled rice. It includes amylose and amylopectin, the proportion of which determines the cooking and eating quality of milled rice. During starch biosynthesis, the key enzymes that control the proportion of amylose to amylopectin are granule-bound starch synthase I (GBSS), soluble starch synthase (SSS) and starch branching enzyme (SBE). Of the three enzymes, GBSS is coded by Waxy and directs amylose biosynthesis; SSS and RBE, coded by sss and rbe respectively, together are in charge of amylopectin biosynthesis. This research transferred the sss and rbel to indica hybrid rice (Oryza sativa L.) restorer line Minghui86 and maintance line Zhengshan97B, and studied their inheritance, expression and relevant utilization in hybrid rice combinations. The main results are as follows:(1) Established agrobacterium-mediated transformation systems for both Minghui86 and Zhengshan97B. Select juvenile embryo 15 days after rice flowering as explants to induce embryogenesis calli; Following 3 to 6 generations of cultures, the embryogenic calli are used as transformation material and precultured for 4 days. Immersed in high concentration of agrobacteria (OD6002.0) for 30 minutes, and cocultured for 3 days in coculture media, the calli are screened by hygromycin. After about one month, resistant calli come out and they are further screened high concentration of hygromycin. The calli that survived finally are thus transferred to differentiation media to grow plantlet.(2) Transferred sss and rbel to Minghui86 and Zhengshan97B and obtained 219 transgenic clones. Of these transgenic clones, 60 were Minghui86 transferred with rbel, 101 Minghui86 transferred with sss, 30 Zhengshan97B with rbel and 28 Zhengshan97B with sss.(3) In the progeny of transgenic rice, about 25% exhibited monogenic(单基因 分离) segregation, and the rest segregated on the basis of high rate separation or distortion. The molecular hybridization results indicated that the clones which segregated aberrantly were multicopy integration and that if integrated into rice genome, the genes could be stably inherited in progeny.(4) RT-PCR determination results indicated that rbel transcription level was enhanced in transgenic pure lines during seed filling stage, and that SSS and RBE had greater enzyme activity in transgenic rice for the period of filling stage, further verifying both of genes specific expression in rice endosperm.( 5 ) Screened and researched transgenic lines with amylose content significantly decreased. 7 pure lines with significantly lowered amylose content were screened in Minghui86 transferred with rbel. 86RF38-3-1-1, the pure line that reduced amylose content most markedly, has a amylose content of 8.8%, decreasing 31.2% relatively compared to control's content(which is 16.8%).10 pure lines with significantly lowered amylose content were screened in Minghui86 transferred with sss. 86SF53-1-1-1, the pure line that reduced amylose content most markedly, has a amylose content of 8.2%, decreasing 35.9% relatively compared to control's content(which is 12.8%).9 pure lines with significantly lowered amylose content were screened in Zhengshan97B transferred with rbel. ZBRF55-4-3-1, the pure line that reduced amylose content most markedly, has a amylose content of 17.8%, decreasing 29.8% relatively compared to control's content(which is 25.5%).12 pure lines with significantly lowered amylose content were screened in Zhengshan97B transferred with sss. ZBSF41 -3-1-1, the pure line that reduced amylose content most markedly, has a amylose content of 18.8%, decreasing 31.1% relatively compared to control's content(which is 27.31%).(6) Screened and researched transgenic lines with softer gel consistency8 pure lines with significantly smaller gel consistency were screened in Minghui86 transferred with rebl. 86RF73-1-1, the pure lines that reduced amylose content most markedly, have a gel consistency of 94mm, relatively 84.3% longer than control's gelconsistency( which is 51mm).8 pure lines with significantly smaller gel consistency were screened in Minghui86 transferred with rebl. 86SF53-1-1, the pure line that reduced amylose content most markedly, has a gel consistency of 73mm, relatively52.0% longer than control's gelconsistency (which is 48mm).No pure line of significantly smaller gel consistency was screened in Zhengshan97B transferred with rbel.10 pure lines with significantly smaller gel consistency were screened in Zhengshan97B transferred with sss. ZBSF11-2-1, the pure line that reduced amylose content most markedly, has a gel consistency of 67 mm, relatively 109.3% longer than control's gelconsistency (which is 34mm).(7) Results of yield investigation for transgenic rice indicated :6 of the 7 pure lines with significantly lowered amylose content in Minghui86...