Tree peonies native to China have become an internationalized ornamental plant and are widely cultivated in many countries in Asia, America, Europe and Australia. Breeding starting from domestication of wild plants through selection of bud mutations and seedlings to hybridization has been done for about 1500 years. At present a few thousand cultivars are cultivated globally in gardens or propag...

Background Tree breeding is logistically complex and expensive, and breeders have long sought to use molecular markers to accelerate breeding. A candidate gene approach based on testing for association between the presence of DNA sequence variation in or near candidate genes, and phenotypic variation in a population has long been explored [1,2]. However, using candidate gene approach (QTLs) has...