Morphogenesis of in vitro strawberry leaf cultured under clinostat 2D condition

The combination of in vitro culture and simulated gravity under clinostat 2D conditions was first applied to strawberry ( Fragaria × ananassa Duch.) leaf to evaluate in vitro morphogenesis, antioxidant enzyme activity and accumulation of endogenous hormones. The subsequent growth and runner formation of clinostat 2D generated-plantlets in the greenhouse as compared to those with plantlets in the in vitro culture condition (control) were also examined. The results showed that the leaf explants (0.5 cm × 0.5 cm) cultured under clinostat 2D gave 1-week shoot regeneration and the growth was higher than that under control condition after 3, 4 and 6 weeks of culture. In addition, in shoots generated from explants under clinostat 2D condition antioxidant enzyme activities affected results such as increasing ascorbate peroxidase (APX), catalase (CAT), 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and reducing phenolic content compared with control conditions after 6 weeks of culture. The clinostat 2D derived-shoots showed higher levels of GA 3 , ABA, and KIN; meanwhile, the content of IAA, ZEA, SA and MEL showed opposite results compared to the control condition. In this study, the ratios between endogenous hormone groups were also different between the two conditions. The ratios of GA 3 /IAA and GA 3 /CYT (ZEA, KIN and 2iP) of clinostat 2D derived-shoots were 12 and 1.5 times higher, respectively, compared to those in the control condition. In contrast, the ratios of IAA/CYT and IAA/SA showed the opposite results (two times lower) after 6 weeks of culture. The growth of shoots and plantlets derived from both conditions showed no abnormalities. In addition, the 2D clinostat generated-plantlets resulted in acclimatization and runner formation that was better than in the control. The results of the study offer a promising new direction for combining in vitro culture and clinostat 2D conditions for plant breeding. Key message In vitro culture and clinostat 2D conditions were applied to study leaf morphogenesis and 3 clinostat 2D-derived subsequent growth strawberry plantlets 4 Morphogenesis of in vitro strawberry leaf cultured under clinostat 2D were compared to 5 those under in vitro culture 6 Subsequent growth and runner formation of clinostat 2D-derived plantlets grown in the 7 greenhouse.