Physiological Resistance Of Sporophytes And Gametophytes In Bryophytes

Biodiversity is the material basis of social and economic development and human survival.However,biological diversity is rapidly losing because of global climate change,and the greenhouse effect intensifies as well as the human’s unreasonable development and the abuse of the natural environment.Bryophyte is more sensitive to human activities and environmental changes than other vascular plants because of their distinctive shape and structure,so their survival challenges are more severe than those of other organisms.Therefore,it is urgent to carry out the protection of bryophytes,especially the endemic and endangered species.Dispersal plays an important role in biodiversity conservation because it can determine the survival,reproduction and extinction of species and the formation of new species.Therefore,it is necessary to fully consider the dispersal properties of species in order to formulate correct biodiversity protection measures.Bryophytes,the second largest group of the terrestrial vascular plant in biodiversity,is characterized by the predominance of gametophytes and the parasitism of sporophytes on gametophytes.As a pioneer plant,bryophytes play an essential role in soil and water conservation and maintenance of the balance of nature.Bryophytes have proven to be highly effective propagators because of their small size and a large number of propagules(spores,gemma,gametophyte fragments...).However,in recent years,analysis of global bryophytes distribution data has suggested that it is not so widespread and that the ocean blocks the spread of bryophytes over long distances.For this reason,in order to protect bryophytes,we must first deepen the correct understanding of their dispersal properties.Dispersal usually includes three links: the release of propagules,diffusion by certain media and successful colonization in new areas.First,the spores or gemma of bryophytes and other propagules can be released by the action of peristomal teeth or the water-wet movement of the elater,the air pressure in the capsule wall or the waterdrops,and enter into the diffusion link.Then,they rely on wind and animals for long-distance dispersal.At present,it is generally believed that bryophytes cannot dispersal by seawater,but there is a lack of relevant experimental data to support it.When the propagule successfully spreads to the new area,whether it can germinate successfully and adapt to the new environment,and then grow into gametophyte is very important for bryophytes to successfully expand the distribution range.Unfortunately,there are minimal researchers on this.Physiological and ecological characteristics of bryophytes are important in predicting their dispersal properties and distribution range.However,due to the difficulty of sampling and in vitro germination culture,there is little research on this study.In this paper,the spores of bryophytes and gametophytes were used as experimental materials.On the basis of successful detoxification and germination culture of various species,the possibility of bryophyte spores spreading through air and seawater was speculated by carrying out experiments on the tolerance of sporophytes to low temperature,dryness and salinity.Through the study of the tolerance of gametophytes to high and low temperatures at different altitudes,to understand the adaptability of gametophytes of bryophytes to thr new environments.The main findings of this paper are as follows:1.Using the method by direct detoxification,eight species of bryophytes(Atrichum undulatum、Brachymenium nepalense 、Brachythecium thraustum、Cirriphyllum cirrosum、Funaria hygrometrica、Haplocladium microphyllum、Isopterygium serrulatum、Pogonatum inflexum)have been successfully cultured,and it lays a foundation for further research on its dispersal properties.2.Spores of 7 species of mosses(Cirriphyllum cirrosum,Atrichum undulatum,Pogonatum inflexum,Brachymenium nepalense,Haplocladium microphyllum,Funaria hygrometrica,Brachythecium thraustum)were dried or treated with low temperature,and their spores were germinated in vitro,the germination rate was observed and recorded.The results showed that the spores of the endemic species,Brachythecium thraustum,were less resistant to low temperature and desiccation than the spores of the other six widely distributed species.3.Eight species of bryophytes(Cirriphyllum cirrosum,Atrichum undulatum,Pogonatum inflexum,Brachymenium nepalense,Haplocladium microphyllum,Funaria hygrometrica,Brachythecium fasciculirameum,Acrolejeunea sandvicensis)were tested for their salt tolerance.The results showed that most kinds of spores could not germinate after soaking in salt solution directly.But,there was found that after soaking in the 3.5% NaCl for 90 days,the spores and capsules of Pogonatum inflexum,Brachymenium nepalense,Haplocladium microphyllum,Funaria hygrometrica are still had high viability(the viability range was 42.98% ~77.24%).It had the possibility of spreading through seawater.4.In this paper,we studied the gametophytes of Thuidiaceae kanedae at different altitudes in Tianmu Mountain and Gaoligong Mountains and found that the gametophytes of Thuidiaceae kanedae at different altitudes were adapted to low temperature while high temperature inhibited the growth of mosses to a certain extent.Moreover,both high and low-temperature tolerance of Thuidiaceae kanedae at high altitude was more durable than that of materials at low altitude,it inferred that the species are mainly under the pressure of abiotic factors in high altitude area.Besides,the species in high altitude area have stronger tolerance to the environment.