Abstract:Rice blast is one of the most important diseases damaging rice. It is important to explore a novel way of improving blast resistance with introducing exogenous resistance genes in modern breeding. In the study, identification and screening of blast resistance in the transgenic rice offspring were conducted using methods of both seedling nursery artificial inoculationand natural infection in field nursery under the conditions of higher resistance selection pressure increased gradually from T2 generation. Seven stable and outstanding McCHIT1-transforming rice lines with the most significant blast resistance were obtained in T5 generation. Detected with 115 Magnaporthe grisea effective isolates from 26 physiological races belonging to seven groups, the resistance frequenciesfor the seven lines were 52.2–61.4%, with 16 percentage higher than those (36.8%) for the control Jinhui 35. Compared with the control, these lines increased the resistance to ZE race group, and improved the resistance to the races of group ZG and ZF as well as dominant group ZB. The McCHIT1-transforming rice lines C36-2-1, C21-6-2, and C21-3-1 were the better combination of higher yield and resistance with seed setting rate of over 80%. The McCHIT1 gene is a certain broad-spectrum resistance gene. The disease-resistant lines with both broad-spectrum resistance and better yield traits can be obtained effectively by introducing McCHIT1 gene under gradually increased selection pressure and screening excellent resistance from resistant lines.