The Identification and Mapping of a Tiller Angle QTL on Rice Chromosome 9

Tiller angle is an important component of plant architecture in rice even though little is known of its mode of inheritance. A quantitative trait loci (QTL) analysis based on a set of recombinant inbred lines extracted from an indica × japonica cross identified a major effect locus (designated qTA‐9a ) on chromosome 9, which was expressed in two independent environments. The qTA‐9a allele derived from the indica parent IR24 increased tiller angle. This QTL was validated in a set of chromosome segment substitution lines involving the same two parental lines. A high resolution genetic map was constructed from a large secondary F 2 population and anchored to the genomic sequence of rice. The QTL was narrowed to a 65‐kb physical region, inclusive of eight putative genes. We have provided the basis for positional cloning of qTA‐9a and have developed markers for a major tiller angle QTL.