Different Improvement Approaches And Effect Of New Plant Type Rice Lines

New Plant Type ( NPT) rice is a new type of rice which was developed at the Philippines-based International Rice Research Institute over a decade and aimed at raising the yield potential of current rice varieties by 30% to 50%. According to field experiments, NPT basically meets the specifications of the breeding design in morphological characters, but exhibits a poor yield performance, because of lower photosynthetic rate (Pn). At the present time, upland rice (Oryza sativa L.) is the development of a new type variety, which has been praised as one of the new source of food supplies in the 21st century in China.Therefore, this paper is intended to improve the drought-resistance to and photosynthetic rate in dry land through wild-crossing. We had obtained excellent drought-resistance plants from wild-crossing progenies. In order to enhance more Pn in NPT upland rice wild-crossing progenies, plant expression PEPC gene of maize (pCB-Zmppc) and sugarcane (pCB-Prbs-Sppc) were transformed into NPT upland rice respectively, by Agrobacterium-mediated transformation system. The photosynthetic parameters in wild-crossing progenies and transformants were measured, the main results are as follows:1,The 6 plants of high drought-resistance were obtained in BC₂F₃wild-crossing progenies at Beijing, keep on selecting in wild-crossing progenies, the biggest Pn from BC₂F₇ generations was 33.2μmol·m^-2·s^-1.2,The colony was compartmentalized five photosynthetic groups by Pn analysis in BC₂F₇ wild-crossing progenies. These groups were respectively"Highest Pn"group,"Higher Pn"group,"Medium Pn"group,"Lower Pn"group and"Lowest Pn"group."Highest Pn"group and"Lowest Pn"group occupied the most proportion; Correlation analysis suggested that Pn had a close correlation with ACE in the"Highest Pn"group and"Lowest Pn"group.3,Compare with CK (H297), the CO2 compensation point was reduced by 27.6%, ACE and AQY were raised by 23.9%,21.8%,respectively. The high capability of photosynthesis in higher light and lower CO2 concentration, which is a necessary basic of photosynthesis for wild-crossing progenies.4,NB medium suitable for NPT upland rice callus induction and subculture. Put 15 g/L sorbitol into NB medium could improve the resistant callus rate significantly. Infect the callus by concentration of Agrobacterium was 0.3 under OD600, which could maximum enhance the resistant callus rate of NPT upland rice more than 20 times. Southern blot analysis showed the maize-PEPC and sugarcane-PEPC genes integrated in most transgenic plants, respectively. And exogenous gene in the progenies passed down stability and in accordance with the Mendelian ratio.5,PEPC activities of the transgenic NPT upland rice leaves were measured. The PEPC activities of 48.9% transformant expressed the maize-PEPC gene are 15²0 times larger than that of the non-transformants, and the highest PEPC activities is 29 times. The PEPC activities of 45.2% transformant expressed the sugarcane-PEPC gene are 4⁶ times larger than that of the non-transformants, and the highest PEPC activities is 13 times. The result demonstrated that the transgenic maize-PEPC gene NPT upland rice exhibition better express efficiently. 6,Gas exchange was measured in some transgenic sugarcane-PEPC genes NPT upland rice lines of T₀ progenies. The Pn increased with the increasing of PEPC activities, but Pn is not closely related to PEPC activities. This indicated that the expressed PEPC boost up the carboxylic efficiency of transgenic plants. Pn was measured in some transgenic sugarcane-PEPC gene NPT upland rice lines of T1 progeny. A remarkable conclusion is the Pn of transgenic NPT upland rice higher than CK (non-transformants) all the time. Especially, under the intense light (≥1500μmol·m^-2·s^-1).