Progress of Apple Rootstock Breeding and Its Use

Apple rootstock breeding has achieved great progress worldwide. In this review, we first summarize the rootstock breeding targets and utilization in main apple-producing countries. Furthermore, we discuss the focus and important research areas of apple rootstock breeding through five aspects: parent selection and setting of crosses, target genes and marker-assisted breeding, root configuration-guided breeding, apomictic resource utilization, and the application of genetic engineering. Finally, we propose an apple rootstock division plan for China, which has a large potential to provide guidance for apple rootstock breeding and utilization in different apple-producing areas of China.