IN VITRO PROPAGATION OF 'LAZARUS' SPECIES THUJA SUTCHUENENSIS FRANCH.

摘要

Thuja sutchuenensis Franch. is a 'Lazarus' species endemic to the limestone karst forests in the Daba Mountains of China. This species is critically endangered due to reproductive problems. The micropropagation of young T sutchuenensis through axillary shoots was reported. Axillary shoots were grown on four media supplemented with different combinations of plant growth regulators (PGRs) for multiplication and three media supplemented with activated charcoal (AC) for elongation. The greatest capacity for axillary shoot induction was achieved on half-strength Schenk and Hildebrandt (SH) medium with 2 mg 1(-1) 6-(4-Hydroxy-3-methylbut-2-enylamino) purine (Zeatin), and the Gupta and Durzan (DCR) medium supplemented with 2 g 1(-1) AC was the most suitable medium for shoot elongation. However, the axillary shoot tips began to die after repeated subcultures were grown on half-strength SH medium. Therefore, DCR was the best medium for the growth of T sutchuenensis axillary shoot tips, but half-strength SH can serve as an occasional multiplication medium to increase the number of shoots, if necessary. It is important for media with PGRs to be alternately replaced with AC-supplemented media to avoid plantlet vitrification or browning caused by the accumulation of PGRs or secondary metabolites in repeated subcultures. The ex vitro cultured shoots immersed in 200 mg 1(-1) IBA rooted after 3 months of culture, with a rooting rate of 61.3%.