Identification and fine mapping of qPH6 , a novel major quantitative trait locus for plant height in rice

Plant height is one of the determinants that influence rice plant architecture and grain yield. Identification of useful novel genes related to plant height is necessary for breeding high-yield rice. In this study, C33084, a backcross introgression line derived from a japonica cultivar (Balilla) as the recurrent parent and an indica cultivar (Dular) as the donor parent, was employed to characterize a novel major quantitative trait locus with a large effect on plant height in rice. C33084 showed a significantly higher plant height than Balilla. Genetic analysis of the F2 and F4 generations deriving from a cross between C33084 and Balilla revealed that this phenotypic variation was controlled by a single Mendelian factor, qPH6, which is located on the long arm of chromosome 6. The recessive allele, qph6, from Balilla has a negative effect on plant height. Fine mapping was carried out with a total of 1,791 recessive individuals from the F2 and F4 generations, and the gene was delimited to a ~41-kb region containing three annotated genes according to available sequence annotation databases. This information could be helpful for future identification and isolation of the candidate genes. Phenotypic evaluation of the near isogenic lines NIL (qPH6) and NIL (qph6) suggested that qPH6 has no pleiotropic effect on other traits. The discovery of qPH6 might be useful for the design and breeding of crops with high grain yield and quality.