分子标记辅助选择改良杂交水稻的白叶枯病抗性

分子标记辅助选择技术以其对目标基因快速而精确的选择为回交育种提供了非常有效的工具。华中农业大学作物遗传改良实验室运用分子标记辅助的回交育种方法，将广谱高抗白叶枯病基因Ｚａ２１迅速导入到杂交水稻的两个优良恢复系明灰６３和６０７８之中，成功地完成了其抗生改良，并通过配组而达到了改良杂交水稻抗性的目的。本研究所运用的分子标记辅助的水稻回交育种程序是：通过一次杂交、二次回交改良杂交水稻抗性的目的。本研究所

Improvement of Bacterial Blight Resistance of Hybrid Rice by Molecular Marker-Assisted Selection

This paper described the practice of molecular marker-assisted select i on (MAS) in the process of recurrent backcrossing to improve the bacterial bligh t (BB) resistance of two restorer lines of hybrid rice, ‘Minghui 63’ and ‘60 78’, by introgressing Xa21, a broad-spectrum BB resistance gene. A PCR-based MAS sy stem for Xa21 introgressing segment was established. It consist ed of a marker r epresenting the Xa21 locus, a marker linked to the Xa21 locus at a distance of 0 .8 cM on one side, and a marker at distance of 3.0 cM from the gene on the other side. In the practice of the improvement of Minghui 63, the selection was carr ied out in tandem in which a recombinant was obtained between Xa21 and one of th e makers in BC1F1, and a subsequent recombinant was obtained between the gen e an d the marker at the other side in BC2F1. The genetic background of Minghui 63 w as recovered in BC3F1 using a total of 128 RFLP markers evenly distributed o n th e 12 rice chromosomes. Thus the improved version of Minghui 63, tentatively ref erred to as 'Minghui 63(Xa21)', was exactly the same as the or iginal Minghui 63 in the entire genome except for a fragment of less than 3.8 cM in length surroun ding the Xa21 locus. A slightly different strategy was adopted for introgressin g Xa21 to 6078, a new restorer line. The main difference is tha t the background selection was carried out mainly in BC1F1, and selections for recombinants were conducted in BC2F1 and BC3F1. Another difference is that AFLP marker w as used for background selection. Both of the improved restorer lines, Minghui 63(Xa 21) and ‘6078(Xa21)’, showed the same level and spectrum of BB re sistance as the do nor parent ‘IRBB21’ with artificial inoculation. Minghui 63(Xa21) and ‘6078(Xa21 )’ also showed the same agronomic performance and combining ability as the orig i nal restorer lines when there is no disease stress. The agronomic performance o f the improved restorer lines, Minghui 63(Xa21) and 6078(Xa21), and their hybrid s was significantly better than the unimproved version under field conditions wi th artificial inoculation.