Abstract: The bacterial leaf blight (BB) resistant gene Xa23 from Zhongye 5112 was introduced into a restorer line Zhongdao 88 and Zhongjing Q-196,which is susceptible to BB by crossing and marker-assisted selection.The Xa23-linked EST marker C189 was used to select Xa23 in the off-spring. Marker-assisted selection (MAS) for Xa23 was performed at booting stages, and followed by conventional selection for agronomic traits at the ripening stage.More than 70 introgression lines that harbored homozygous Xa23 and showed stable agronomic traits were obtained.Forty-four of the introgression lines were subject to BB disease inoculation at the booting stages,and results showed that all the tested lines were resistant to the most destructive Xoo strain PXO 99 (P6). These results clearly suggested that the Xa23-linked marker C189 could be conveniently and effectively used in the BB-resistance breeding programs．

Key words: rice (Oryza sativa L.), molecular marker-assisted selection (MAS), Xa23, rice bacterial leaf blight