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通过基因枪转基因方法和双质粒共转化体系将Xa21基因转入优良恢复系明恢63,得到转基因系M12和M22,并进一步做田间试验、新品种选育和食用安全性评价。结果显示:M12和M22对中国的所有白叶枯病小种都表现出高度抗性,但与原受体品种明恢63相比,农艺性状上有许多变异,主要表现在:结实率、千粒重等农艺性状变差,与珍汕97A的配合力显著降低;但与温敏不育系(X07S、056S)配组的F1有较好的田间表现。通过多代回交和分子标记辅助选择,成功地将Xa21基因从M12株系转到保持系80-4B和不育系80-4A中,得到抗白叶枯病的皖21B和皖21A。并利用皖21A不育系选育出优良杂交组合抗优97(皖21A×R-18),该组合在两年区域试验和一年生产试验中产量表现突出,米质优良。对不同世代和不同遗传背景的转基因品系进行白叶枯病鉴定和Southern分析表明:Xa21基因都能稳定遗传和正常表达,连续16代的种植并没使其白叶枯病的抗性减弱或丧失,而且不论Xa21基因是纯合的还是杂合的都有相同的抗性表现。对大鼠和小鼠的饲喂试验表明:转基因大米实质上等同于非转基因大米,是安全无害的。
The Xa21 gene was transferred into Minghui 63, a transgenic restorer line, by gene gun transgenic method and double plasmid co-transformation system, and transgenic lines M12 and M22 were obtained. Field experiments, selection of new varieties and evaluation of food safety were also conducted. The results showed that M12 and M22 showed high resistance to all the bacterial blight isolates in China, but there were many variations in agronomic traits compared with Minghui 63, which mainly manifested in: seed setting rate, 1000-grain weight The agronomic traits such as temperature-sensitive genic male sterile (X07S, 056S) decreased with the decreasing of the combining ability with Zhenshan97A. Through multiple generations of backcrossing and molecular marker-assisted selection, the Xa21 gene was successfully transferred from the M12 line to the maintainer line 80-4B and the sterile line 80-4A to obtain the resistant strains of leaves 21B and 21A. The excellent hybrid combination “Youyou 97” (Anhui 21A × R-18) was bred by Anhui 21A CMS. The combination showed excellent yield and excellent grain quality in two years regional experiment and one year production experiment. Bacterial blight identification and Southern analysis of the transgenic lines of different generations and different genetic backgrounds showed that the Xa21 gene could be stably inherited and normally expressed. The continuous 16 generations did not weaken or lose the resistance to bacterial leaf blight , And the same resistance performance regardless of whether the Xa21 gene is homozygous or heterozygous. Feeding trials in rats and mice showed that GM rice is virtually identical to non-GMO rice and is safe and harmless.