Orthogonal test design for optimization of the cryopreservation of Chinese cherry (Prunus pseudocerasus L.) shoot tips by vitrification

To optimize the protocols of the conservation for Chinese cherry (Prunus pseudocerasus Lindl.), in vitro-grown shoot tips of 'Taishanganying' were used as the material and an orthogonal test and single factor test were designed. The result showed that the optimal step of vitrification cryopreservation was: 50 days in vitro plantlets were cold hardened at 4 degrees C for 3 weeks. The shoot tips were peeled and precultured in 0.3 mol L-1 sucrose concentrations preculture medium for 1 day. Then they were treated with loading solution (LS) for 20 min before exposure to PVS3 at 0 degrees C for 90 min and plunged directly in liquid nitrogen (LN) where they were kept for at least 2 h. After thawing in 42 degrees C, 1 min, they were washed twice with DS. Two weeks after regrowth, the survival rate was 87.8%. Regenerated plants showed the same morphological characteristics as the control. It is proved to be viable and could be used for long-term storage of this species.