2007 Volume 57 Issue 4 Pages 305-314
To avoid drowning under flooded conditions, deepwater rice responds to rising water level by rapid internode elongation. Quantitative trait locus (QTL) analysis, using a deepwater rice cultivar (Oryza sativa) and a wild rice species (O. rufipogon) with deepwater characteristics, revealed the presence of major QTLs (qTIL12, qNEI12 and qLEI12) in a common chromosomal region that regulates internode elongation. Genetic analysis revealed that a QTL inherited in a dominant manner, was located on the long arm of chromosome 12. A nearly isogenic line (NIL), produced by backcross introduction of a chromosome fragment carrying this major QTL into non-deepwater rice, exhibited a dramatic internode elongation in response to water rise. This indicates that the difference between deepwater rice and non-deepwater rice is associated with the presence of the QTL, and that this sequence is sufficient to confer deepwater characteristics. Although deepwater rice and non-deepwater rice share a common machinery for internode elongation; non-deepwater rice cannot activate the machinery in response to flooding, unlike deepwater rice which harbors this major QTL.
