In Vitro Micropropagation Of Three Mosses

Bryophytes are one of important parts of nature, and are playing an active role in improving human living environment and exhibiting important function in city greening. Bryophytes are expected to reduce the heat-island effect and improve gardening and air quality. The characteristics such as extreme temperature tolerance, desiccation resistance and easy maintenance make bryophytes a superior material for greening. According to geographical features of Shanghai, three mosses with ornamental values:Bryum argenteum Hedw., Racomitrium japonicum Dozy & Molk and Brachythecium fasciculirameum C.Mull were selected. Bryum argenteum and Brachythecium fasciculirameum are very common species in Shanghai and are tolerant to environment; while Racomitrium japonicum is desiccation-resistance and appropriate for roof and wall greening.The present research aims to explore the methods of micropropagation of the three mosses, and satisfy the need for mass production of materials in practical. In the present studies, axenic materials were obtained by using the shoots of three wild mosses as explants. We investigated reproduction models and the effects of the type of cultural media, different culture methods, phytohormones, and light, sugars on the growth of mosses. The main results are as follows:1 Based on the life cycle of Bryum argenteum in cultivation, a procedure for micropropagation was established. The protonemata were grown in liquid culture and introduced onto solid media for gametophore development. The derived gametophores were broken into pieces by a blender and inoculated onto a sterilized substrate. A moss mat formed after 30 days.2 Effects of media on protonema multiplication and gametophore induction of Bryum argenteum were investigated. Phytohormones (IAA,6-BA, GA3) were also tested on gametophore induction. The results showed that (1) protonemata were most easily reproductive in Knop solution, compared with other liquid media (BCD and Beneke); (2) The protonemata introduced to Knop (solid) produced more gametophores than those cultivated with other solid media; (3) 0.1 uM GA3 added to the Knop medium reduced the number of days that were needed for gametophore emergence. Bryum argenteum can grow well on substrates:a mixture of vermiculite and peat (6:1), peat, gardening soil, vermiculite and better than materials from wild.3 Racomitrium japonicum could produce a lot of protonemata by tissue culture, but it failed to obtain gametophores from cultured protonemata in vitro.4 Compared with liquid culture, protonemata of R. japonicum grew better in solid culture. In solid culture, media types, sugars, light, phytohormones, culture density on protonema growth and gametophore induction were investigated. All factors were not the sufficient condition for inducing gametophores stably. However, they influenced the growth of protonemata.15 g/l glucose promoted protonema biomass in nitrate-only media (BCD) but markedly reduced the bud number; 30 g/l sucrose had the best result in promoting protonema biomass in low-ammonium and nitrate media (Beneke). Beneke supplemented with 2,4-D made protonemata green and beautiful.5 For Brachythecium fasciculirameum, the model of gametophore multiply in liquid culture was taken. Derived gametophores then were air-dried and disintegrated by a blender and inoculated to sterilized substrates. A compressed moss mat formed after 60 days.6 20 g/l glucose and 0.1 uM GA3 were supplemented in Knop liquid culture which could promote the growth of gametophores of Brachythecium fasciculirameum. After 60 days, the biomass was nearly 21 times of the biomass of the control. When transferred to peat, gardening soil or vermiculite, the shoots can propagate themselves. On peat, the moss grew best.