Physiological and Proteomic Analyses of Different Ecotypes of Reed (Phragmites communis) in Adaption to Natural Drought and Salinity

Drought and salinity are the two major abiotic stresses constraining the crop yield worldwide. Both of them trigger cellular dehydration and cause osmotic stress which leads to cytosolic and vacuolar volume reduction. However, whether plants share a similar tolerance mechanism in response to these two stresses under natural conditions has seldom been comparatively reported. There are three different ecotypes of reed within a 5 km2 region in the Badanjilin desert of Northwest China. Taking the typical swamp reed (SR) as a control, we performed a comparative study on the adaption mechanisms of the two terrestrial ecotypes: dune reed (DR) and heavy salt meadow reed (HSMR) by physiological and proteomic approaches coupled with bioinformatic analysis. The results showed that HSMR and DR have evolved C4-like photosynthetic and anatomical characteristics, such as the increased bundle sheath cells (BSCs) and chloroplasts in BSCs, higher density of veins, and lower density and aperture of stomata. In addition, the thylakoid membrane fluidity also plays an important role in their higher drought and salinity tolerance capability. The proteomic results further demonstrated that HSMR and DR facilitated the regulation of proteins associated with photosynthesis and energy metabolism, lipid metabolism, transcription and translation, and stress responses to well-adapt to the drought and salinity conditions. Overall, our results demonstrated that HSMR and DR shaped a similar adaption strategy from the structural and physiological levels to the molecular scale to ensure functionality in a harsh environment.

Flora and Vegetation Characteristics of the Natural Habitat of the Endangered Plant Pterygopleurum neurophyllum

This study analyzed the flora, life form, and vegetation of the Nakdong River wetland. Vegetation analysis was performed on 37 plots using the phytosociological method of the Zürich-Montpellier School. PCA analysis was conducted by using the vegetation data (ground cover of class; 1~9) of 37 plots surveyed by phytosociological method. PCA (Principal Component Analysis) was used to statistically analyze the objectivity of the community classification and the character species. The traditional classification and mathematical statistic methods were used. A total of 82 taxa belonging to 28 families, 65 genera, 72 species, 2 subspecies, and 8 varieties were present in the vegetation of the survey area. The life form was analyzed to be the Th-R5-D4-e type. The communities were classified into seven communities: Miscanthus sacchariflorus community, Phragmites communis community, Phragmites communis–Carex dispalata community, Ulmus parvifolia community, Zizania latifolia community, Setaria viridis community, and Salix koriyanagi–Salix chaenomeloides community. As a result of PCA analysis, it was classified into seven communities. Seven communities were analyzed, where the most dominant species (M. sacchariflorus, P. communis, C. dispalata, U. parvifolia, Z. latifolia, S. viridis, S. koriyanagi, S. chaenomeloides) of each community were examined as character species. Another species is analyzed as Salix koreensis. Of the sixteen M. sacchariflorus communities, Pterygopleurum neurophyllum was present in six plots (A-2 group) but not in ten plots (A-1 group). These two groups showed differences in coverage and the number of occurring species. As for the relative net contribution degree (r-NCD) in the A-2 group, most species showed low r-NCD except for M. sacchariflorus, which showed an r-NCD of 100. The r-NCDs in the A-1 group were as follows: Miscanthus sacchariflorus (100), P. neurophyllum (21.74), and Persicaria perfoliata (10.14). Therefore, P. neurophyllum is difficult to grow in the A-1 group. As a result, it is thought that the high density of M. sacchariflorus affects the growth and distribution of P. neurophyllum. In order to expand and maintain P. neurophyllum, the habitat environment needs to be altered by adjusting the density of M. sacchariflorus.

Cadmium Uptake, In Vivo Metastasis and Subcellular Environmental Response of Five Wetland Plants Using DFT Method

The main purpose of this study is to analyze whether Cd2+ affects the absorption of Ca2+ and Fe2+ by the roots of five wetland plants and the toxic mechanism of cadmium on the subcellular structure. Five wetland plant samples were collected from the constructed wetland in the upper reaches of the Yangtze River. Based on the experiment and density function theory (DFT), we measured the Cd2+ content in the root, stem, and leaf, the morphological dimensions of plants, and in the subcellular structure the electronic activity of Cd compound was calculated to describe the stability and activity of the products. In general, Zephyranthes candida,Cynodon dactylon, Arundo donax, and Pontederia cordata have distinct cadmium uptake characteristics, while Phragmites communis does not. The results indicated tolerance to cadmium in all but Phragmites communis, which was due to cadmium distribution through the process of transpiration and a mechanical interception. The simulation results showed that Cd2+ imposed no obvious inhibition on the absorption of Ca2+ and Fe2+ in plants, as the energy barrier of the process is about 1–3 eV. Cd2+ could improve the amount of pyruvate and glucose by 30% via spd orbital hybridization, making them more chemically reactive. At the same time, Cd2+ could replace Mg2+ in chlorophyll through a copper substitution reaction, making the electron energy of chlorophyll more concentrated. As a result, the valence-band electron at −40 eV was vacant. In conclusion, we determined that Cd2+ has no obvious inhibitory effect on Ca2+ and Fe2+ in root absorption and that Cd2+ could affect the properties of compounds of the subcellular structure and thus produce physiological toxicity.

Assessment of the effect of water-table depth on riparian vegetation along the middle and lower reaches of the Manasi River, Northwest China

The Manasi riparian zone in northwestern China has become a survival habitat for numerous native plant species and requires urgent protection owning to rapid expansion of farmland. The critical factor affecting the growth of desert riparian vegetation in arid regions is recognized to be groundwater, but in this region the threshold of water-table depth for riparian species has been rarely studied. To determine the association between species and their major growth factors and to ascertain the water-table depth threshold, this study employed field investigation, a logarithm distribution model and canonical correspondence analysis. According to the findings, (1) the water-table depth largely regulates the species distribution; (2) from the results of the logarithm distribution model, the water-table depth appropriate for herbs is 1–1.5 m and for shrubs it is 2–4 m, and a water-table depth of less than 6 m could satisfy the growth requirement of major species; (3) species diversity peaks at the water-table depths of 2–3, 3–5, and 2–4 m for herbs, shrubs and all species, respectively; (4) the frequency of appearance of Phragmites communis (grass herb) and Tamarix chinensis (deciduous shrub) was not as sensitive to depth to water table. To reconstruct a riparian zone, Phragmites communis and Tamarix chinensis could be planted in areas with water-table depth of less than 3 m and 2–5 m, respectively. These results may contribute to suitable policy regarding vegetation restoration.