Abstract
Deepwater rice is cultivated in Southeast Asia where serious flood occurs periodically. To avoid flood condition, deepwater rice elongates its internode along with the rising water. QTL analysis, using a deepwater rice cultivar in Bangladesh and a wild rice species that carry deepwater characteristics, revealed one major QTL for internodal elongation on the long arm of chromosome 12 in both rice strains. This indicates that the QTL on chromosome 12 is the key locus for internode elongation under water submergence condition in deepwater rice. Nearly isogenic line (NIL) carrying this region confirmed the existence of this QTL and indicated that it is inherited as a dominant manner. As all deepwater rice characteristics were observed in this NIL plant, the QTL locus may function as a master gene for deepwater characteristics. Using this NIL, the relationship between the major QTL gene and plant hormones, ethylene and gibberellin, will be discussed.
