Abstract:
Vanda coerulea is a rare Thai orchid that faces problems in conservation
attempts that is desired in this research. The effects of media (modified Vacin and
Went 1949 (VW), Murashige and Skoog 1962 (MS)), sucrose concentrations (0-30
g/l) and plant growth regulators (BA, TDZ and NAA) were studied on
micropropagation of Vanda coerulea from shoot tips. Shoot tips cultured on VW
agar medium supplemented with 10 g/l sucrose showed higher shoot and root
formation than those cultured on MS medium. Addition of 1 mg/l BA to VW agar
medium was found to be the best for induction of shoots from shoot tips. The
combination of 0.5 mg/l NAA and 2 mg/l TDZ was found to be the best for root
formation from shoots. Survival rate of plantlets cultured in the greenhouse was
100%. There was no difference in morphology and similar patterns of ploidy level
of stock plants and regenerated plants.
Seeds of Vanda coerulea were successfully cryopreserved using direct
plunging into liquid nitrogen, vitrification, encapsulation-dehydration and
encapsulation-vitrification. The manipulation of encapsulated seeds was much
easier than vitrification. Protocorms, shoot tips and protocorm-like bodies of
Vanda coerulea were successfully cryopreserved by encapsulation-dehydration in
combination with loading solution, slow freezing and droplet-vitrification,
respectively. The highest regrowth of cryopreserved protocorms was 40% with
35% water content after 8 h dehydration. The survival rate of cryopreserved shoot
tips and cryopreserved protocorm-like bodies without exposing to PVS2 solution
was 20% and 5 %, respectively. The RAPD marker was able to be efficiently used
for estimating the genetic variation of plantlets. The same RAPD patterns of noncryopreserved
and cryopreserved protocorm-like bodies were observed. The size
and sequences of the trnL (UAA) region of cpDNA for non-cryopreserved and
cryopreserved protocorm-like bodies were not different. There was no difference
in morphology and similar patterns of ploidy levels of non-cryopreserved and
cryopreserved plantlets. The successful development of the methods will lead to
more successful preservation of Vanda coerulea