Morphological,Tissue Culture And Physiological And Biochemical Characteristics Of Bryophytes In Baiyun Obo Rare Earth Mining Area

In this paper,the morphological characteristics,in vitro tissue culture and related physiological and biochemical characteristics of mosses in the Baiyun Obo rare earth mining area were analyzed.The results were as follows:There were significant differences in the plant height,stem width,leaf length,and leaf width among the 8 species of mosses in the Helan Mountain and mining area.The ratio of length to width of leaves and the aspect ratio of leaf cells?upper,middle,and base?were not significantly different.It shows no obvious change in leaf cell shape and leaf shape.It may be due to different climatic conditions and the content of rare earth elements.We compared three common species of mosses in different rare earth mining areas of Baiyun Obo,in terms of leaf length and leaf width,the results are West Mine>Main Mine>East Mine and with significant differences between West Mine and East Mine.leaf cell especially the basal cells are the smallest in the main mining area.This also shows that during the growth process of mosses,rare earth may be enriched in the base of leaves.The results show that the content of rare earth elements is one of the main factors for mosses growth,and maybe affect it through the leaves.The tissue culture conditions of three dominant mosses Didymodon tectorum,Syntrichia sinensis,Tortula atrovirens in the study area were sifted.The effects of plant hormones on the induction of protonema and callus were explored.The results showed that the best disinfectant for Didymodon tectorum gametophyte was 75%alcohol immersion for 30 seconds and 1.5%NaClO for 45 seconds.The mass concentration of 0.1mg/L IAA induced the formation of Didymodon tectorum protonema,the mass concentration of 0.5mg/L6-BA induced callus growth and promoted the explant to differentiate forming the bud.The optimum disinfectant time for Syntrichia sinensis gametophyte were 75%ethanol immersion for 60 seconds,followed by a 2%NaClO for 30 seconds.The mass concentration of 0.2 mg/L IAA promoted the formation of callus,the mass concentration of 0.5 mg/L6-BA was appropriate for the bud formation.The spores of the Tortula atrovirens were disinfected with 75%ethanol for 60 seconds,and then disinfected with 1%NaCl O for 60 seconds.The mass concentration of0.5 mg/L 6-BA promoted the formation of green protonema.Three physiological indexes,including POD vitality,MDA and chlorophyll content were determined to check out the influences of the rare earth elements stress under gradient concentrations treatment.We choosed the rare earth La³⁺,Ce⁴⁺and Y³⁺three elements and setted respectively six concentrations under the single element stress,in order to explore the physiological response and changes of Didymodon tectroum to the rare earth stress.The Ce⁴⁺element significantly increased the POD activity at 5 mg/L,the content of MDA was significantly increased at 10mg/L.It showed that the Didymodon tectorum had a stronger response to Ce⁴⁺stress,lower degree to La³⁺.The contents of chlorophyll a,chlorophyll b and total chlorophyll increased significantly at lower concentrations of La³⁺?2.5 mg/L?and Ce⁴⁺?5 mg/L?,decreased obviously at higher concentrations of all three rare earth elements.This study laid the foundation for further exploration of the effects of rare earth elements on the growth and the development of mosses in the Baiyun Obo rare earth mineral area.