Asymbiotic seed germination and in vitro conservation of Coelogyne nervosa A. Rich. an endemic orchid to Western Ghats

Abstract

Coelogyne nervosa is an epiphytic orchid endemic to Western Ghats, South India. The mature seeds of C. nervosa were cultured on ½ MS (Murashige and Skoog), MS, Kn (Knudson) and VW (Vacin and Went) media to evaluate the seed germination response. Of the four basal media used, MS medium supported maximum seed germination. Further experiments to enhance seed germination were done on MS medium supplemented with various concentrations (10, 20, 30 and 40 %) of coconut water (CW). Thirty percent CW gave the highest response in terms of percent seed germination (96), fresh weight (7.2 mg/seedling) and protocorm length (15.2 mm). Since CW containing medium did not support further seedling growth, each seedling was isolated and cultured on MS medium supplemented with either BA (6-benzylaminopurine) or Kin (kinetin) alone (1.0-4.0 mg/l each) or in combination with NAA (1-naphthaleneacetic acid; 0.2-1.0 mg/l). Maximum growth was observed on MS medium supplemented with BA (3.0 mg/l) and NAA (0.5 mg/l). On this medium, the seedlings reached an average length of 3.6 cm with 2.8 well expanded green leaves per seedling. Similarly, optimum, healthy, white root induction (3.3 roots/seedlings) was also observed on the same medium. The rooted seedlings were successfully transplanted to pots with 91 % success.The 2-year-old tissue culture derived plants produced normal flowers and fruits.

In vitro protocorm development and mass multiplication of an endangered orchid, Dactylorhiza hatagirea

“…(MS + 15 µm NAA + 15 µm BAP) in 28 days (Gogoi et al, 2012), and in Coelogyne nervosa Lindl. (MS + 3 mg/L BAP + 1 mg/L NAA) in 90 days (Abraham et al, 2012). Multiple shoots were formed in MS + 6 µm IAA + 18 µm BAP + 18 µm Kin in 49-56 days in Malaxis khasiana (Hook.f.)…”

Asymbiotic germination in three Chloraea species (Orchidaceae) from Chile

“…Many orchids are economically important (Dearnaley 2007, Dearnaley et al 2012, mainly for their beautiful flowers which made them stand out among ornamental plants (Abraham et al 2012). Chloraea and Gavilea are the most represented orchid genus in Chile (Elórtegui & Novoa 2009, Novoa et al 2015.…”

“…In nature, orchids reproduce by seeds and depend on direct association with specific (to some degree) mycorrhizal fungi to germinate (Murguía & Lee 2007, Pereira et al 2005, Smith & Read 2008, Valadares et al 2012. As stated early, this dependency is due to the minimal amount, or even absence, of nutrients stored in the small seeds of orchids (Elórtequi & Novoa 2009, Smith & Read 2008, Abraham et al 2012. The fungal partner supplies the required nutrients for embryo growth, nutrients that can also be supplied by specific culture media (Knudson 1946, Nadarajan et al 2011.…”

“…Orchids are highly valued plant species, mainly due to their applications as ornamental plants, bioresources for perfumes and medicines, and condiments (Dearnaley 2007, Dearnaley et al 2012, Abraham et al 2012. Most of these species are from the tropics, and are cultivated and propagated in controlled conditions (Stenberg & Kane 1998, Kauth et al 2006.…”

“…Asymbiotic germination can be more effective than symbiotic germination for several reasons; 1) it does not require the isolation and identification of the mycobiont of the target orchid species. 2) It allows for more controlled, aseptic conditions, resulting in less overall contamination (Johnson et al 2007, Aggarwal & Zettler 2010, Abraham et al 2012. 3) In symbiotic germination, the seeds inoculated with the mycorrhizic fungi can be completely covered with the fungal hyphae, making difficult the evaluation of germination and embryo development (personal observation), sometimes requiring a change in the culture media, increasing the risk of contamination.…”