Preliminary Study On Peach Rejuvenation Using Tissue Culture

Peach (Primus persica) belongs to Rosaceae Prunus and is an important fruit tree and ornamental species. Although graft is the main propagation method for peach trees, it has obviously defects. Especially after long-term asexual reproduction, there is decline in the quality of flowers, leaves and peach fruit, which finally leads to variety degeneration. Traditional rejuvenation approaches are through cultivation means, which can not eliminate the peach tree debilitation, while tissue culture can induce somatic embryos or adventitious buds development and help to restore the cell totipotency.In this study, different cultivars of peach,’Feicheng hongli’,’Feicheng baili’,’Shenzhou baimi’,’Shenzhou hongmi’,’Baibitao’and’Ziyebitao’were used as materials. The peach tissue culture system was established through axillary bud culture, followed by the induction of embryogenic callus generation from leaves of the peach plantlets and adventitious buds. Then paraffin sections were prepared to detect the type of callus, and callus was further induced to differentiate to form new plants. This work will provide theoretical basis for the peach varieties rejuvenation. Main results are as follow:The peach tissue culture system was established using axillary buds as explants, the optimal procedure of sterilization for primary cultrue is:75%alcohol soaked for30s, and then0.1%mercuric chloride for6-7min.2.5cm long axillary bud is the most suitable type of explant, and the survival rate could reach34.5%. Best sampling time is March, April and October.As for proliferation culture, optimal proliferation medium of all varieties are:’Fei cheng hongli’ was MS+6-BA1.0mg/L+IBAO.1mg/L,’Feicheng baili’was MS+6-BA1.0mg/L+IBA0.1mg/L orG+6-BA1.0mg/L+IBA0.1mg/L,’Shenzhou hongmi’and’Shenzhou baimi’was MS+6-BA1.0mg/L+IBA0.1mg/L,’Ziyebitao’and’Baibitao’were G+6-BA1.0mg/L+lBA0.2mg/L or MS-R+6-BA1.0mg/L+JBA0.2mg/L.The best subculture interval for’Shenzhou hongmi’,’Ziyebitao’and’Baibitao’ was20days/times. After been subcultured for several times,’Shenzhou baimi’began to show vitrification.According to the vitrification of’Shenzhou baimi’, further study was performed and results showed that the incidence of vitrification decreased to27%with improved medium:MS-1/4NH4NO3+6-BA0.3mg/L+IBA0.1mg/L+sucrose40g/L+agar7g/L, light intensity25001x, temperature20C, polypropylene sealing film.In leaf regeneration study, leaves, especially the base part, were suitable for induction of callus after20days culture. Among the cultured leaves,9.3%of them can be induced to form embryogenic callus in the mediu MS+2,4-D1.0mg/L+6-BA0.5mg/L+TDZ0.05mg/L, but these callus samples were failed to differentiated to adventitious buds.For ’Shenzhou hongmi’,’Shenzhou baimi’,’Ziyebitao’and’Baibitao’, tissue culture seedlings with complete callus in base part can be induced to form adventitious buds by been subcultured repeatedly in their optimal proliferation medium.There are five different kinds of callus derived from leaves and axillary bud. Paraffin sections showed that some of these are embryogenic callus and the other are non-embryogenic callus. Embryogenic callus can differentiaed to form adventitious buds through the period of the globular embryo, heart-shaped embryo and torpedo embryo. But the non-embryogenic callus had large cells and loose structure and is difficult to differentiate.