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Rheum palmatum L. is a perennial herb of the Rheum genus Polygonaceae. It is a traditional Chinese herbal medicine which has extremely high medicinal value. Rhubarb has scarce seeds in subtropical regions, and natural planting conditions have limitations. In recent years, the demand of rhubarb has increased, and the means of sowing and raising seedlings can no longer meet the needs of the market. Traditional sowing and propagation methods have limitations such as long cycle and low reproduction coefficient. Tissue culture technology can shorten the reproduction cycle that increase the reproduction coefficient and maintain the excellent characteristics of the parents, which is an effective way to promote the large-scale and commercial production of fine varieties of rhubarb. The results of the study showed that: (1) Analysis of the characteristics of Qinghai Rhubarb seeds. (2) Seed sterilization treatment. (3) Primary culture medium selection. (4) Callus induction. (5) Callus proliferation culture. (6) Hypocotyl callus bud differentiation.(7)Rooting culture. (8) Qinghai Rhubarb tissue culture seedling transplantation. Using the method of the present invention to establish a Qinghai Rhubarb in vitro culture aseptic propagation system, high-quality Qinghai Rhubarb seeds as explants and different hormone medium ratios, Qinghai Rhubarb hypocotyl induction rate reached 90%, and the proliferation coefficient reached 4.3. The survival rate of transplanting tissue cultured seedlings reaches 95% which can improve the reproduction efficiency of Qinghai Rhubarb, and provide theoretical basis and technical support for subsequent research on transgenic and genetic improvement. It can also provide a basis for medicinal value for the systematic research and commercial production of Qinghai Rhubarb.

No abstract

Plant breeding is one of the manifestations of sustainable landscape regeneration. The CRISPR/Cas9 system is a new type of genome-directed editing technology modified from the acquired immune defense response in bacteria and archaea. Due to its efficiency and multi-function, it is widely used in animals, plants, microorganisms and other fields. In sustainable plant landscape, the system makes the gene mutate to improve plant varieties, morphological characteristics, and flowering dates, which can increase the variety of landscape. This article discusses the general situation of CRISPR/Cas9 technology and the progress of plant application, summarizing the problems and countermeasures, and looking forward to the application of sustainable landscape plants. Landscape plants are genetically complex. CRISPR/Cas9 technology can improve plants without genome references and cultivate new ornamental varieties, which can accelerate the breeding process of sustainable landscape plants.

The mountainous region of northwest Yunnan is a multi-ethnic region in China where several ethnic groups, such as the Tibetans, Lisu, and Naxi, reside. This study utilises the average nearest neighbour index, kernel density analysis, and GeoDetector (Geographical Detector) to analyse the spatial distribution characteristics of different types of ethnic villages, their correlation with the natural environment, and differences in the influence of various natural environmental factors. The results show the following: (1) the spatial distribution of the three types of ethnic villages in the mountainous region of northwest Yunnan are clustered. (2) Tibetan villages are characterised by high elevation, gentle slopes, proximity to the river, low annual average temperature, and low annual precipitation. Lisu villages are characterised by medium elevation, steep slopes, high annual average temperature, and high annual precipitation. Multi-ethnic villages are characterised by low elevation, medium slopes, proximity to rivers, high annual average temperature, and high annual precipitation. (3) Ethnic villages are affected by various natural factors such as elevation, slope, river buffer zone, annual average temperature, annual precipitation, and ecological environment. Among these, ecological environment has the greatest impact on Tibetan villages, and annual precipitation has the greatest impact on Lisu and multi-ethnic villages. (4) The distribution of the Tibetan villages is mostly constrained by the composite factors of ecosystem and precipitation, while that of the Lisu villages by the composite factors of precipitation and elevation, and that of the multi-ethnic villages by the composite factors of precipitation and temperature.