Identification and chromosome doubling of interspecific hybrids from Fragaria viridis × F. mandshurica

- Three hybrids were obtained from F. viridis × F. mandshurica and showed several traits of both parents.
- Colchicine and oryzalin were used for tetraploid induction, and using 0.1% (w/v) colchicine to shoot tips for 48 h was the best.
- We obtained 18 allotetraploids and 31 mixoploids that showed stronger growth vigor than corresponding diploid hybrid.

Three offspring (LsDb-11-01, LsDb-11-02, and LsDb-11-03) obtained from the interspecific hybridization of two diploid strawberry species (F. viridis 42 × F. mandshurica 43) were analyzed using morphological characteristics observation, chromosome counting, karyotype analysis and sequence-related amplified polymorphism (SRAP) identification. The results identified that the three hybrids had several confirmed features of both parents. Despite the poor growth vigor, including crumpled and unevenly colored leaves, smaller inflorescences, almost sterile flowers and thinner stolons, three progenies also showed erect inflorescences, more flowers per inflorescence and stronger stolon reproduction capability compared to parents. The self-pollination of all progenies failed, except for an abnormal fruit obtained from progeny LsDb-11-01 under open pollination conditions. The chromosome doubling of LsDb-11-01 was performed with colchicine and oryzalin and resulted in the successful creation of 18 allotetraploid and 31 mixoploid accessions. The best tetraploids inducing treatment was applying 0.1% (w/v) colchicine to shoot tips for 48 h. LsDb-11-01 and all allotetraploids experienced a convalescent period during which crimpled and unevenly colored leaves became normal. The allotetraploids presented stronger vigor with thicker stems, larger and greener leavers compared to those of the stock parents. This study provides several materials (three hybrids, 18 allotetraploids and 31 mixoploids) for further breeding of new strawberry germplasms.