Abstract:

The crosses were made between four japonica rice (Oryza sativa L.) landraces Bodao, Tieganqing, Jiangnanwan and Queernuo from Taihu Lake region, which were highly resistant to the blast (Magnaporthe grisa), and a susceptible japonica variety Suyunuo to produce F1 and F2 generations. The P1 , P2, F1 and F2 generation from various combinations were inoculated separately with Japanese blast strain Hoku 1 and Chinese races ZE3 and ZG1 to study genetic patterns of resis-tance in the four landraces to the blast. Resistance in Bodao, Tieganqing or Queernuo to blast Hoku 1 might be controlled by a dominant gene, and in Jiangnanwan by two inhibiting effect genes. Resistance in Tieganqing or Queernuo to blast ZE3 might be controlled by one dominant gene, and in Bodao and Jiangnanwan by two independently dominant genes and two inhibiting effect genes, respectively. Resistance in Tieganqing to blast ZG1 might be controlled by a dominant gene, but in Bodao and Jiangnanwan by two inhibiting effect genes. The crosses were further made between landrace Bodao and 12 Japanese differential varieties possessing the known resistance genes to the blast to produce F1 and F2 generations. The plants of various generations were inoculated with strain Hoku 1 to confirm the resistance gene in Bodao was allelic with known resistance genes. The results show that the resistance gene in Bodao to strain Hoku 1 was non allelic with known resistance genes, and tentatively designated Pi-bd1(t).