A Morphometric And Molecular Studr In Didymodon Tectorum Complex And The Tesscu Cultivation Of Didymodon Tectorum

Didymodon Hedw., affiliated to Musci Bryales Pottiaceae, is one of the most important components of acrocarpous mosses in the area of north temperate zone. The climate and moisture of loess hill and the path inclination are convenient for the mosses of Didymodon to form microbiotic soil crust. We find that D. tectorum is the dominant species in these soil crusts. Soil crust palys a significant role in propecting the environment, therefore, it is meaningful to do some experiments and studies on D. tectorum.On the one hand, based on morphologic characteristics datas to do a primary Taxonomic identify on the D. tectorum complex which includes D. tectorum, Didymodon cordatus, Didymodon vinealis, and a variation named Didymodon tectorum (Mull. Hal.) K. Saito var. pusillus D. P. Zhao, T. R. Zhang & X. D. Zhao sp. nov., in addition to discuss the classified boundary among these similar species. After morphologic identification, a molecular phylogenetic analysis of the relationship among this complex is presented, which is based on five chloroplast regions rps4, trnL-F, apB-rbcL, psbH-T, psbA-trnH, and the gene trees are established by the method of MP, ML, NJ. On the other hand, we culture the spores of D. tectorum under the aseptic condition, and summarize the characteristics of spore and protonema during this germination. Otherwise, we also select the best pattern to disinfect capsula and the suitable medium to cultivate spores. Primary discussions about the effects of phytohormone on the protonema are also given in this dissertation. The main results are as follows:1. A new variation is describe and named as Didymodon tectorum (Mull. Hal.) K. Saito var. pusillus D. P. Zhao, T. R. Zhang & X. D. Zhao sp. nov., it can be distinguished from D. tectorum var. tectorum by its smaller leaves, and the weakly recurved margin of leaves. The leaf of the variation is 0.5-0.8mm long, which is only half of D. tectorum var. tectorum.2. We suggest the independent status of these three species according to both morphological and molecular evidences. D. tectorum and D. vinealis are the sister groups in the gene trees. D. vinealis is obviously separated from D. tectorum and D. vinealis.3. We also select the best method to disinfect capsula by orthogonal experiment, the best pattern is 75s1%NaClO+1min70% alcohol. The Knop medium is more suitable to cultivate spores compared to 1/2MS medium. The type of spore gemination is similar to Bryum type, Macromitrium type, and Tetraphis type.4. IBA can promote protonema to become longer,6-BA can induce more muds. The number of muds are about 25.8 after adding 1.0 mg/L IBA+1.0 mg/L 6-BA, these muds can develope into normal gametophytes, therefore this phytohormone pattern is the best group to promote the development of protonema and mud.