Functional Characterization of the MeSSIII-1 Gene and Its Promoter from Cassava.

Soluble starch synthases (SSs) play important roles in the synthesis of cassava starch. However, the expression characteristics of the cassava SSs genes have not been elucidated. In this study, the MeSSIII-1 gene and its promoter, from SC8 cassava cultivars, were respectively isolated by PCR amplification. MeSSIII-1 protein was localized to the chloroplasts. qRT-PCR analysis revealed that the MeSSIII-1 gene was expressed in almost all tissues tested, and the expression in mature leaves was 18.9 times more than that in tuber roots. MeSSIII-1 expression was induced by methyljasmonate (MeJA), abscisic acid (ABA), and ethylene (ET) hormones in cassava. MeSSIII-1 expression patterns were further confirmed in proMeSSIII-1 transgenic cassava. The promoter deletion analysis showed that the -264 bp to -1 bp MeSSIII-1 promoter has basal activity. The range from -1228 bp to -987 bp and -488 bp to -264 bp significantly enhance promoter activity. The regions from -987 bp to -747 bp and -747 bp to -488 bp have repressive activity. These findings will provide an important reference for research on the potential function and transcriptional regulation mechanisms of the MeSSIII-1 gene and for further in-depth exploration of the regulatory network of its internal functional elements.

The effect of alfalfa cultivation on improving physicochemical properties soil microorganisms community structure of grey desert soil.

Planting alfalfa in grey desert soil can have significant effects on soil nutrient levels, microbial communities, and overall soil improvement. High-throughput sequencing technology was used to explore the relationship between the rhizosphere microbial community structure of grey desert soil planted with different alfalfa varieties (Aohan, WL525HQ, Knight2, Kangsai, Victoria, and WL712), alfalfa characteristics and rhizosphere soil physicochemical properties. Alfalfa planting increased the nitrogen and organic matter in the grey desert soil, and the effects in Victoria, Kangsai, and Aohan were relatively better than those in the unplanted areas and other alfalfa areas. The Chao1 and Shannon indexes showed that the diversity and relative abundance of bacteria and fungi in Kangsai were significantly higher than those in the unplanted areas and other alfalfa areas. Redundancy analysis showed that available nitrogen and phosphorus, as well as fresh weight, significantly affected the changes in fungal and bacterial communities. Variance partitioning analysis showed that soil and alfalfa growth characteristics explained 50.04% and 51.58% of the structural changes in the bacteria and fungi, respectively. Therefore, planting alfalfa changed the community structure of bacteria and fungi, as well as the content of soil nutrients, and different varieties of alfalfa had different effects on soil improvement.

The life span and influencing factors of metal mesh in artificial soil on railway rock-cut slopes in humid areas.

The stability of slope is strengthened by the metal mesh. The studies of the life span and influencing factors of metal mesh in the artificial soil in humid areas will guide ecological restoration of rock-cut slopes in Southwest China. Due to metal corrosion, the fixation function of the metal mesh could last for 10 years. The factors of soil contents, soil electrochemical properties and soil bacteria not only changed with the vegetation succession but also weakened the effect of the metal mesh on soil fixation for slope protection. The potential gradient, chloride ion content, sulfate ion content and water content were the main influencing factors for metal mesh corrosion during the vegetation restoration stage from 0 to 5 years, while the corrosion potential, potential gradient, chloride ion content, and water content were the main influential factors for metal mesh corrosion during the vegetation restoration stage after 11 years. At different vegetation restoration stages, the soil bacteria contained different dominant species, which had spatial heterogeneity, and the heterogeneity of the soil bacteria was another factor influencing the corrosion of the buried metal mesh. Meanwhile, the plant root as a soil fixation function strengthened with time, and 8 years later, the local woody plants gradually migrated to form a community dominated by multiple woody species. It is the first time that the life span of a metal mesh under the artificial soil of rock-cut slopes and factors affecting the different corrosion stages of the metal mesh in a humid area have been judged. The fixation function of plant root gradually replaces metal mesh, and main factors affecting the process include soil contents, soil electrochemical properties and soil bacteria. The research on corrosion factors of metal mesh under artificial soil for rock-cut slopes will contribute towards reducing the environmental risk of ecological restoration.

Vegetation and soil nutrient restoration of cut slopes using outside soil spray seeding in the plateau region of southwestern China.

Outside soil spray seeding (OSSS) is used widely for road cut revegetation, and the artificial soil used in OSSS can improve slope soil conditions and nutrients, and help promote plant growth and succession. Three different slopes was investigated to evaluate the effectiveness of OSSS for restoration, including a natural slope (NS), a cut slope without any artificial recovery treatment (CSW) and a cut slope treated with OSSS (CSO). The recovery of cut slopes was determined by evaluating a number of factors, including indices associated with plants on the slopes, soil enzyme activities (urease and sucrase), and soil nutrient content (soil organic matter (SOM), total phosphorous (TP), total potassium (TK), available nitrogen (AN), available phosphorous (AP), available potassium (AK), potassium (K+), calcium (Ca2+), magnesium (Mg2+), and sulphate (SO42-)). The results indicated that the vegetation and soil conditions differed between the three slopes. The Shannon-Wiener index (H), the Simpson index (D), and the Margalef index (R) values from the CSO and NS were lower than those of the CSW, whilst the Pielou index (E) value and vegetation canopy cover were higher for the CSO and NS than for the CSW. The content of SOM and AN in soil from the CSO was lower than in soil from the NS and CSW, and content of many nutrients were higher in soil from the CSO than in soil from the NS and CSW. This suggests that the restoration of vegetation and soil nutrients on the CSO was relatively successful. Our results indicated that the use of OSSS to restore cut slopes is effective in plateau areas. However, despite improvements in soil nutrient levels, there were still nutritional imbalances. Therefore, more attention should be paid to balancing nutrients in the later stage of OSSS implementation for the recovery of cut slopes at high altitudes.