Micropropagation and chromosome stabilities of four endangered species of orchids in Indonesia

Abstract

The combination of BA and NAA in concentration at 0-4 mg/l could not significantly induce shoot primordia in four endangered species of orchids. Size of shoot meristem used in the preliminary research might be too big to induce shoot primordia in Grammatophyllum speciosum and for increasing the survival frequency of Vanda and Phalaenopsis. Certain concentrations of BA and NAA affected the survival frequency of Vanda and Phalaenopsis. The type of basal medium has no effect to the growth and the survival frequency of the orchid studied, except for Phalaenopsis gigantea which only grow well in Hyponex-pepton medium. The chromosome numbers of the four orchid species showed very high stabilities during the courses of their micropropagations. Many Indonesian orchids are in endangered, which are mostly caused by over hervest and deforestation. More than 90 Indonesian orchid species have been listed in WCMC (World Conservation Monitoring Center, Cambridge University, UK) as endangered species. Because of their economic values many of them have still illegally been taken from the nature, especially the ones that are difficult to cultivate and propagate. Therefore, it is important to study the cultivation and propagation of the endangered orchid species, so people will buy only the cultivated orchids and not anymore take the orchid directly from the wild habitat. This study is also needed to support the reintroduction program to recover the species populations in their natural habitats. MATERIALS AND METHODS To study the effect of the type of liquid basal medium supplemented with benzyl adenine (BA) and naphthalene acetic acid (NAA) at various concentrations in combination on the induction on four endangered Indonesian orchid species. Preliminary study was conducted in the Laboratory of Plant Chromosome and Gene Stock, Graduate School of Science, Hiroshima University, Japan for 1.5 months. Basal medium used were: 1. Half strength of B5 medium (Gamborg et al. 1968): 1/2 B5+20 g/l sucrose 2. Half strength of MS medium (Murashige and Skoog 1962): 1/2 MS+20 g/l sucrose) 3. Hyponex-pepton medium: 3 g/l Hyponex+2 gr/l peptone +20 g/l sucrose Combination between BA and NAA used were based on Tanaka and Ikeda works (1983), i.e.: 1. 5 concentrations of BA (0; 0.02; 0.2; 2.0 and 4.0 mg/l) and 2. 5 concentrations of NAA (0; 0.02; 0.2; 2.0 and 4.0 mg/l) This combination form 25 treatments The endangered Indonesian orchids studied here were: 1. Grammatophyllum speciosum Blume (2n=38) 2. Coelogyne pandurata Lindley (2n=40) 3. Vanda tricolor Lindrey (2n=38) 4. Phalaenopsis gigantea J. J. Smith (2n=38) (Shoji 1976) The number of shoot meristem (0.5-2 mm length) used for each species are 300 shoot meristems (3 basal medium x 25 treatment x 4 replication/treatment). RESULTS AND DISCUSSION 1. Grammatophyllum speciosum Blume Four weeks after planting, 98% of the shoot meristem of G. speciosum (0.5-1.0 mm length) are survive. It seem the basal medium has no effect on the survival frequency of the shoot meristem, although the 1/2 MS basal medium show the lowest value (95%). The concentration of BA and NAA also seem has no effect to the survival of shoot meristem (Table 1). However, the growth of G. speciosum seem affected by basal medium, BA and NAA used. Compare to 1/2 B5 and 1/2 MS medium, growth length of G. speciosum shoot is higher on Hyponex-pepton basal medium. The increase of NAA concentration from 0 to 0.2 mg/l increase the shoot length of G. speciosum. However, the concentration of NAA above 0.2 mg/l highly decrease the shoot growth of G. speciosum (Table 2).