Elucidating the genetic background of the early-flowering transgenic genetic stock T1190 with a high-density SNP array

Apple trees have a long juvenile period, which makes apple genetic improvement via breeding costly and time-consuming. Transgenic genetic stocks carrying the early-flowering gene BpMADS4 have been used to reduce the juvenility of apple from five or more years to less than 10 months. One such genetic stock, T1190, has been used widely in breeding and research. It was reported to be a seedling of ‘Pinova’ but the other parent was unknown. Not knowing the alleles that this unknown parent contributed to T1190 brings uncertainties to breeding programs and research studies. In this study, the full pedigree of the genetic stock T1190 was reconstructed using an apple 20K SNP array and a panel of 530 reference cultivars and breeding selections. T1190 was determined to be an offspring of ‘Pinova’ and ‘Idared’. The full pedigree of T1190 was used to deduce the mosaic ancestor composition of the transgene-hosting chromosome. Such knowledge is useful to ensure breeding programs and research studies achieve their expected objectives.