2018 ASHS Annual Conference

The morden, cultivated strawberry is propagated vegetatively using stolons and crown as clones, but it is required the many labor and time for the propagation of the nursery plant, and become the cause of greatly reducing yield by viruses and pathogen infection. Therefore, seed propagation in strawberry plants has been in demand for a long time. The present study aimed to test genetic stability of F₁ hybrids strawberry through crosses between S9 generation plants of inbred lines derived from octoploid strawberry, because the stability and uniform phenotypes of F₁ hybrids strawberry have been confirmed in prior studies. Breeding of inbred lines (S9 generations) for seed propagation in octoploid strawberry could be achieved that individuals showing inbreeding depression were eliminated and vigorous individuals were selected, resulting in a strong heterosis of F₁ hybrids through crosses between inbred lines. Genetic stability of F₁ hybrids strawberry was tested using seven simple sequence repeat(SSR) markers. We detected high (<0.90) genetic similarity among individuals of F₁ hybrids and individuals of S9 or S11 inbred lines derived from ‘Benihoppe’, ‘Toyonoka’, and ‘Akihime’, the original ovary and pollen parental cultivars. The genetic similarity among inbred lines increased with the advancement of selfing generations, and that of F₁ hybrids produced through hybridization between inbred lines was also very high. Although the genetic similarity among these individual inbred lines and F₁ hybrids was very high, some variation was detected, but it did not result in morphological differences. With the advancement of selfing generations, the yield and fruit weight tended to decrease in the F₁ hybrids. To develop commercially useful seed-propagated cultivars, the breeding techniques such as the effects of different cross combinations or crossing among and within selfing generations should be investigated.