Abstract
DNA markers has been used in the genetic analysis of natural variations observed among rice varieties, such as heading date, environmental stress tolerance, and morphological traits. We have performed a quantitative trait locus (QTL) analysis of heading date using progenies derived from several cross combinations and have identified 15 QTLs controlling heading date in rice. Several QTLs for heading date have been cloned by means of a map-based cloning strategy. The successful cloning of heading date QTLs clearly contributed to our understanding of the genetic control mechanism of heading date in rice. Marker-based genetic approaches can also be used to analyze other complex traits as well as heading date. QTLs with major effects have been identified on seed dormancy, cool-temperature tolerance at the booting stage, seed longevity, Al tolerance, tolerance of P deficiency etc. This approach greatly facilitates the exploitation of agronomically and scientifically important genes in natural variants.
