Developing Rice Lines Resistant to Bacterial Blight and Blast with Molecular Marker-Assisted Selection

Abstract

The bacterial blight (BB) and blast are two major diseases of rice. Through Molecular Marker-assisted Selection (MAS) and traditional breeding methods, hybridization and selfcross, blast resistance gene Pi9(t), BB resistant genes Xa21 and Xa23 were put together. Four stable lines L17–L20 which conferred 3 homozygous resistance genes and good agronomic charac- teristics were obtained through consecutive inoculation in the field or/and greenhouse, MAS and selection from agricultural as- pects. By artificial inoculation of 20 blast isolates which came from different countries and areas, 7 Chinese epidemic bacterial blight races and an Anhui epidemic BB race in the field or/and greenhouse, 4 lines expressed resistance to blast and BB. L17–L20 had high resistance to all 20 blast isolates and showed similar resistant level to and same resistant spectrum as donor variety 75-1-127. At the same time, lines L17–L20 had similar resistance and spectrum to Xa23 gene both in seedling and heading stages. In the adult stage, the lines had better BB resistance than donor parents M12 with Xa21 gene and CBB23 with Xa23 gene. Using multi-PCR, gene Pi9(t) and Xa21 can be selected at the same time so that improves the selection efficiency.