Shoot basal ends as novel explants for in vitro plantlet regeneration in an elite clone of tea.

摘要

An efficient system for organogenesis from shoot basal ends was established using an elite clone of Camellia sinensis L.O.Kuntze. In this study, factors that affected the efficiency of shoot regeneration, including explant type (i.e., young leaves, tender stems, or shoots), and plant growth regulators [PGRs; thidiazuron (TDZ), benzyladenine (BA), or indole-3-butyric acid (IBA)] were investigated. Callus induction and subsequent plantlet regeneration were significantly affected by explant type as well as by the level of endogenous and exogenous PGRs. At 0.1 micro M TDZ, leaf and stem explants produced callus which failed to regenerate buds during subsequent shoot induction. In contrast, 100% of shoot basal end explants produced callus at all concentrations of TDZ. Shoot basal calli, induced on medium supplemented with 0.1 micro M TDZ and 0.49 micro M IBA, gave the highest mean percentage of shoot regeneration (67.4%) on medium supplemented with 8.88 micro M BA plus 0.49 micro M IBA during subsequent shoot induction. Callus initiation on media containing TDZ affected the subsequent regeneration of plantlets; however, the continued presence of TDZ inhibited later regeneration during subsequent sub-cultures. For the C. sinensis clone, 'Longjing 43', the presence of a basal callus during shoot elongation was essential to avoid the deterioration of shoots. Rooting was achieved when the basal cut-end of elongated shoots was dipped in 2.45 mM IBA for 5 min, followed by transfer to PGR-free medium. Elongated shoots treated with 2.45 mM IBA gave the highest rooting percentage (70.8%). Rooted plants could be established in soil with a survival frequency of 60-70%. This regeneration system may be considered for the improvement of tea clones through genetic manipulation.