Abstract: The dwarfing gene D-53 is one of a few dominant genes for dwarfing in rice (Oryza sativa L.). In the present study, our genetic analysis confirmed that mutant characteristics including dwarfing, profuse tillering, thin stems and small panicles are all controlled by the dominant D-53 gene. We measured the length of each internode of KL908, a D-53-carrying line, and classified the dwarfism of KL908 into the dn-type. In addition, we measured elongation of the second sheath and -amylase activity in the endosperm, and we characterized KL908 as a dwarf mutant that was neither gibberellic acid-deficient nor gibberellic acid-insensitive. Using a large F2 population obtained by crossing KL908 with a wild-type variety, NJ6, the D-53 gene was mapped to the terminal region of the short arm of chromosome 11, with one simple sequence repeat marker, Ds3, co-segregating, and the other, K81114, located 0.6 cM away.(Author for correspondence.Tel:010 6487 0491; Fax: 010 6487 3428； E-mail：lhzhu@genetics.ac.cn)

Key words: dominant dwarf gene, genetic analysis, genetic mapping, rice.