Paenibacillus rhizolycopersici sp. nov., an oligotrophic bacterium isolated from a tomato plant in China.

A Gram-positive, rod-shaped, motile, endospore-forming strain, DXFW5T, was isolated from the rhizosphere soil of tomato. Strain DXFW5T grew at 20-50 °C (optimum, 25-37 °C), pH 5-8 (optimum, pH 7) and in the presence of 3 % NaCl. It was positive for catalase and oxidase. Phylogenetic analysis using 16S rRNA gene sequences showed this strain was most closely related to Paenibacillus timonensis DSM 16943T (98.0 %) and Paenibacillus barengoltzii DSM 22255T (97.4 %). The DNA G+C content was 52.9 mol%. The digital DNA-DNA hybridization values between strain DXFW5T and P. timonensis DSM 16943T, P. barengoltzii DSM 22255T and P. macerans DSM 24T were 33.1, 24.9 and 21.2 %, respectively. The average nucleotide identity values between strain DXFW5T and P. timonensis DSM 16943T , P. barengoltzii DSM 22255T and P. macerans DSM 24T were 86.93, 81.77 and 75.98 %, respectively. The major fatty acids were anteiso-C15 : 0 (55.1 %), iso-C16 : 0 (13.2 %) and C16 : 0 (10 %). The polar lipids of strain DXFW5T consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine two unidentified phospholipids and three unidentified lipids. MK-7 was the major isoprenoid quinone. Based on these results, it was concluded that the isolate represents a novel species of the genus Paenibacillus, for which the name Paenibacillus rhizolycopersici sp. nov. is proposed, with DXFW5T (=ACCC 61751T=JCM 34488T) as the type strain.

Chitinophaga hostae sp. nov., isolated from the rhizosphere soil of Hosta plantaginea.

A Gram-negative, rod-shaped aerobic bacterium designated as strain 2R12T was isolated from the rhizosphere soil of Hosta plantaginea. Phylogenetic analyses based on the 16S rRNA gene revealed that strain 2R12T should be assigned to the genus Chitinophaga with the highest sequence similarity to Chitinophaga arvensicola DSM 3695T (99.1 %) and Chitinophaga ginsengisegetis DSM 18108T (98.6 %). The major fatty acids of strain 2R12T (>10 %) were iso-C15 : 0, C16 :1 ω5c and iso-C17 : 0 3-OH. The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids and five unidentified lipids. The predominant respiratory quinone was MK-7. The genomic DNA G+C content was 46.1 mol%. The average nucleotide identity values of strain 2R12T with C. arvensicola DSM 3695T and C. ginsengisegetis DSM 18108T were 77.9 and 78.8 %, respectively, while in silico DNA-DNA hybridization values for strain 2R12T with these strains were 22.8 and 23.3 %, respectively. Based on comparative analysis of phylogenetic, phylogenomic, phenotypic and chemotaxonomic characteristics, strain 2R12T represents a novel species in the genus Chitinophaga, for which the name Chitinophaga hostae sp. nov. is proposed. The type strain is 2R12T (=ACCC 61757T=JCM 34719T).

Metabacillus rhizolycopersici sp. nov., Isolated from the Rhizosphere Soil of Tomato Plants.

A Gram-positive, endospore-forming, rod-shaped and aerobic bacterium, with swarming and swimming motility, designated strain DBTR6T, was isolated from the rhizosphere soil of tomato plants. Strain DBTR6T grew at 20-45 â„ƒ (optimum 30-37℃), pH 4-9 (optimum 7-8) and at salinities from 0 to 5% (optimum 1%). Phylogenetic analysis using 16S rRNA gene sequences showed this strain belonged to the genus Metabacillus and was most closely related to Metabacillus litoralis DSM 16303 T (98.3%) and Metabacillus sediminilitoris MCCC 1K03777T (98.3%). The DNA G + C content of the genomic DNA was 36.4%. The digital DNA-DNA hybridization value between strain DBTR6T and reference strains M. sediminilitoris MCCC 1K03777T and "M. bambusae" BG109T were less than 70% (26.7% and 26.0%), and the average nucleotide identity score were less than 95% (78.55% and 78.38%), and the Amino Acid Identity values calculated were less than 96% (79.99% and 80.18%), respectively, suggesting that strain DBTR6T represented a novel species in the genus Metabacillus. Chemotaxonomic analysis showed that strain DBTR6T contained MK-7 as the major respiratory quinone. The predominant fatty acids (> 10.0%) were iso-C15:0, anteiso-C15:0 and C16:0. The major polar lipids were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), glycolipids (GL) and three unidentified lipids (L). Based on the differential physiological properties, biochemical characteristics and genotypic data, strain DBTR6T represents a novel species of the genus Metabacillus, for which the name Metabacillus rhizolycopersici sp. nov. is proposed. The type strain is DBTR6T (= ACCC 61900 T = JCM 35080 T).

Rhizobium rhizolycopersici sp. nov., Isolated from the Rhizosphere Soil of Tomato Plants in China.

During characterization of rhizobacteria, strain DBTS2T was isolated from the rhizosphere soil samples of healthy tomato plants and characterized using a polyphasic taxonomic approach. Phylogenetic analysis using 16S rRNA gene sequences showed this strain belonged to the genus Rhizobium and was most closely related to Rhizobium subbaraonis JC85T (99.1%) and Rhizobium daejeonense CCBAU 10050T (97%). Cells of strain DBTS2T were Gram-negative, short rod, aerobic and non-motile. This novel strain was found to grow at 20-45 °C (optimum 25-37 °C), pH 5-9 (optimum 8) and in the presence of 4% NaCl. It was positive for catalase and oxidase. The predominant cellular fatty acids were Summed Feature 8 (52.7%) and C19:0 cyclo ω8c (23.3%). The polar lipids of strain DBTS2T consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified aminophospholipid, unidentified aminolipid, four unidentified phospholipids, unidentified lipid, phosphatidylcholine, unknown glycolipid and unknown aminophosphoglycolipids. Q-10 was the major quinone. The DNA-DNA hybridization similarity values between the strain DBTS2T and R. subbaraonis JC85T, R. daejeonense CCBAU 10050T and Rhizobium azooxidifex DSM100211T were 46.4%, 20.7% and 25.5%, respectively. The ANI value was 91.96% between strain DBTS2T and R. subbaraonis JC85T and 75.18% between strain DBTS2T and R. daejeonense CCBAU 10050T. The DNA G+C content of the genomic DNA was 63.1 mol%. Based on these results, it was concluded that the isolate represents a novel species of the genus Rhizobium, for which the name Rhizobium rhizolycopersici sp. nov. is proposed, with DBTS2T (= CICC 24887T = ACCC61707 = JCM 34245) as the type strain.

Dickeya oryzae sp. nov., isolated from the roots of rice.

A novel Gram-stain-negative strain, designated ZYY5T, was isolated from rice roots. Results of 16S rRNA gene analysis indicated that strain ZYY5T was a member of the genus Dickeya, with a highest similarity to Dickeya zeae DSM 18068T (98.5%). The major fatty acids were summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C16:0 and summed feature 8 (C18:1 ω7c and/or C18:1 ω6c). Multi-locus sequence analysis using five concatenated genes (16S rRNA, atpD, infB, recA and gyrB) and phylogenomic analysis based on 2940 core gene sequences showed that strain ZYY5T formed a robust cluster with strains EC1, ZJU1202, DZ2Q, NCPPB 3531 and CSL RW192, while separated from the other strains of D. zeae. The orthologous average nucleotide identity (ANI) and digital DNA-DNAhybridization (dDDH) values among these six strains ranged from 96.8-99.9% and 73.7-99.8%, which supported that they were belonged to the same species. However, strain ZYY5T shared 58.4 of dDDH and 94.5% of ANI values with type strain D. zeae DSM 18068T, which were lower than the proposed species boundary cut-off for dDDH and ANI. The genomic analysis revealed that strain ZYY5T contained virulence-associated genes, which is same as the phylogenetic-related strains of the genus Dickeya. Based on the results of the polyphasic approaches, we propose that strain ZYY5T represents a novel species in the genus Dickeya, for which the name Dickeya oryzae sp. nov. (=JCM 33020 T=ACCC 61554 T) is proposed. Strains EC1, ZJU1202, DZ2Q, NCPPB 3531 and CSL RW192 should also be classified in the same genomospecies of D. oryzae same as ZYY5T.

Gracilibacillus oryzae sp. nov., isolated from rice seeds.

A Gram-stain-positive, facultatively anaerobic, endospore-forming bacterium, designated strain TD8T, was isolated from surface-sterilized rice seeds (Oryza sativa L.). Phylogenetic analysis of the 16S rRNA gene indicated that strain TD8T should be placed within the genus Gracilibacillus (95.2-99.0 % sequence similarity); it exhibited highest similarities to Gracilibacillus ureilyticus CGMCC 1.7727T (99.0 %), 'Gracilibacillus xinjiangensis' CGMCC 1.12449T (98.9 %) and Gracilibacillus dipsosauri CGMCC 1.3642T (97.5 %). Chemotaxonomic analysis showed that menaquinone-7 (MK-7) was the major isoprenoid quinone. Diphosphatidylglycerol, phosphatidylglycerol and one unidentified phospholipid were the major cellular polar lipids, and the major fatty acids were anteiso-C15 : 0, anteiso-C17 : 0, iso-C15 : 0, C16 : 0 and iso-C16 : 0, which supported the allocation of the strain to the genus Gracilibacillus. The digital DNA-DNA hybridization value between strain TD8T and Gracilibacillus ureilyticus CGMCC 1.7727T was lower than 70 % (22.60 %), and the average nucleotide identity score was 79.54±5.09 %, suggesting that strain TD8T represented a novel species in the genus Gracilibacillus. The genomic DNA G+C content was 37.5 %. Based on physiological and biochemical characteristics and genotypic data, strain TD8T represents a novel species of the genus Gracilibacillus, for which the name Gracilibacillus oryzae sp. nov. is proposed. The type strain is TD8T (=ACCC 61556T=CICC 24889T=JCM 33537T).

Strain Conditions Monitoring on Corroded Prestressed Steel Strands in Beams Based on Fiber Bragg Grating Sensors.

Fiber Bragg Grating (FBG) sensors, with excellent properties, have been widely adopted to monitor the mechanical parameters in civil engineering in recent years. On the other hand, the current study on fatigue performance of corroded prestressed steel strands is still limited, and this is mainly because the long-term strain conditions monitoring is difficult to conduct. Based on the aforementioned considerations, a total of six beam specimens were fabricated in this study. The loading mode of four points bending was adopted in the form of sinusoidal waves in the experiments. On basis of the experimental results, it can be concluded that the fatigue life of the beam decreases sharply with the increase of the corrosion rate of steel strands. Besides, with the increase of the maximum fatigue load, the fatigue life of the beam will decrease significantly. Furthermore, the existing fatigue damage of steel strand inside the beam before corrosion may further accelerate its fatigue failure. As a result, the fatigue life of the beam is reduced because of the stress concentration. Under the same external load, the strain increment and the residual strain of steel strands in the stages of loading and unloading after corrosion increase significantly compared with other stages, while the existing residual strain always shows an increasing trend at various static loading stages. Therefore, the corrosion of steel strand seriously affects not only its mechanical properties, but also its fatigue performance. Finally, the FBG sensors are capable of measuring the steel strand strain, as well as the long-term strain conditions.

Urban green space area mitigates the accumulation of heavy metals in urban soils.

Despite that the heavy metals in urban soils pose a threat to public health, the critical factors that influence their concentrations in urban soils are not well understood. In this study, we conducted a survey of surface soil samples from urban green spaces in Shanghai, to analyze the concentrations of the key heavy metals. The results showed that Zn was the most abundant metal with an average concentration of 122.99 mg kg-1, followed by Pb (32.72 mg kg-1) and Cd (0.23 mg kg-1). All concentrations were found to be below the risk screening values defined by the National Environmental Quality Standards for soils of development land in China (GB36600-2018), indicating no current risk in Shanghai. However, there was a clear accumulation of heavy metals, as the mean concentrations were significantly higher than the background values. Furthermore, we explored the relationships between key heavy metals with population density, GDP and green space area. Both Spearman correlation and Random Forest analysis indicated that per capita green space area (pGSA) and population density were the most crucial factors influencing the status of heavy metals in urban soils, unlike edaphic factors e.g. SOM content in farmland soils. Specifically, there was a significantly positive linear correlation between heavy metal concentrations and population density, with correlation coefficients ranging from 0.3 to 0.4. However, the correlation with pGSA was found to be non-linear. The nonlinear regression analysis revealed threshold values between heavy metals concentrations and pGSA (e.g Zn 22.22 m2, Pb 24.92 m2, and Cd 25.92 m2), with a sharp reduction in heavy metal concentrations below the threshold and a slow reduction above the threshold. It suggests that an increase in per capita green space area can mitigate the accumulation of heavy metals caused by growing population density, but the effect is limited after the threshold. Our findings not only provide insights into the distribution patterns of heavy metals in the urban soils at the local scale, but also contribute to the urban greening at the global scale and offer guidance for city planning in the face of increasing population densities over the coming decades.

Transgenic expression of lactoferrin imparts enhanced resistance to head blight of wheat caused by Fusarium graminearum.

BACKGROUND: The development of plant gene transfer systems has allowed for the introgression of alien genes into plant genomes for novel disease control strategies, thus providing a mechanism for broadening the genetic resources available to plant breeders. Using the tools of plant genetic engineering, a broad-spectrum antimicrobial gene was tested for resistance against head blight caused by Fusarium graminearum Schwabe, a devastating disease of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) that reduces both grain yield and quality. RESULTS: A construct containing a bovine lactoferrin cDNA was used to transform wheat using an Agrobacterium-mediated DNA transfer system to express this antimicrobial protein in transgenic wheat. Transformants were analyzed by Northern and Western blots to determine lactoferrin gene expression levels and were inoculated with the head blight disease fungus F. graminearum. Transgenic wheat showed a significant reduction of disease incidence caused by F. graminearum compared to control wheat plants. The level of resistance in the highly susceptible wheat cultivar Bobwhite was significantly higher in transgenic plants compared to control Bobwhite and two untransformed commercial wheat cultivars, susceptible Wheaton and tolerant ND 2710. Quantification of the expressed lactoferrin protein by ELISA in transgenic wheat indicated a positive correlation between the lactoferrin gene expression levels and the levels of disease resistance. CONCLUSIONS: Introgression of the lactoferrin gene into elite commercial wheat, barley and other susceptible cereals may enhance resistance to F. graminearum.

Optimal spatial sampling design for monitoring potentially toxic elements pollution on urban green space soil: A spatial simulated annealing and k-means integrated approach.

Sampling design in soil science is critical because the lack of reliable methods and collecting samples requires tremendous work and resources. The aims were to obtain an optimal sampling design for assessing potentially toxic elements pollution using pilot Pb soil samples from the urban green space area of Shanghai, China. Two general steps have been used. The first step is to determine the optimum sample size against improving the prediction accuracy and monitoring costs using the spatial simulated annealing (SSA) algorithm. Secondly, we evaluated their likely placement of new extra sampling points by integrated SSA with k-means (SSA+ k-means) and expert-based (SSA+ expert-based) sampling methods. The improvement of sampling design by the integrated sampling approaches was evaluated using mean kriging variance (MKV), root mean square error (RMSE), and mean absolute percentage error (MAPE). The findings indicated that adding and placing 350 new monitoring points upon the existing sampling design by SSA increased the prediction accuracy by 64.35%. The MKV for the optimized SSA+ k-means sample was lower than by 4.12 mg/kg, 9.46 mg/kg compared with locations optimized by SSA and SSA+ expert-based method, respectively. Optimizing new sampling locations by SSA+ k-means sampling method was reduced MAPE by 9.26% and RMSE by 7.13 mg/kg compared to optimizing by SSA alone. However, there was no improvement in placing the new sampling points in SSA+ expert-based sampling method; instead, it increased the error by 8.11%. This paper shows integrating optimization approaches to evaluate the existing sampling design and optimize a new optimal sampling design.

[Problems and countermeasures of soil health quality in urban green space]. / 城市绿地土壤健康质量问题与对策.

Soil quality of urban green space (UGS) is the basis for ensuring healthy growth of plants and maintaining the healthy ecosystem services for the residents and the sustainable development of city. At present, in order to improve the soil quality of UGS, more attention has been paid to fertility quality and environmental quality, but less to the health quality. We analyzed the concept, connotation, and assessment indicator of soil health quality, summarized the main problems and challenges of soil health quality of UGS. Finally, we put forward the ways and strategies to improve soil health quality of UGS, and prospected future research direction. Our aim was to attract the attention to the soil quality of UGS, especially soil health quality, and the importance of comprehensively improving soil quality of UGS, eventually providing strong technical support for urban sustainable development and eco-city construction.

The Optimization Strategy of the Existing Urban Green Space Soil Monitoring System in Shanghai, China.

High concentrations of potentially toxic elements (PTE) create global environmental stress due to the crucial threat of their impacts on the environment and human health. Therefore, determining the concentration levels of PTE and improving their prediction accuracy by sampling optimization strategy is necessary for making sustainable environmental decisions. The concentrations of five PTEs (Pb, Cd, Cr, Cu, and Zn) were compared with reference values for Shanghai and China. The prediction of PTE in soil was undertaken using a geostatistical and spatial simulated annealing algorithm. Compared to Shanghai's background values, the five PTE mean concentrations are much higher, except for Cd and Cr. However, all measured values exceeded the reference values for China. Pb, Cu, and Zn levels were 1.45, 1.20, and 1.56 times the background value of Shanghai, respectively, and 1.57, 1.66, 1.91 times the background values in China, respectively. The optimization approach resulted in an increased prediction accuracy (22.4% higher) for non-sampled locations compared to the initial sampling design. The higher concentration of PTE compared to background values indicates a soil pollution issue in the study area. The optimization approach allows a soil pollution map to be generated without deleting or adding additional monitoring points. This approach is also crucial for filling the sampling strategy gap.

Mixed plantations of Metasequoia glyptostroboides and Bischofia polycarpa change soil fungal and archaeal communities and enhance soil phosphorus availability in Shanghai, China.

Soil degradation has been found in urban forests in Shanghai, especially in the pure plantations. Mixed plantations are considered to improve soil quality because they can stimulate organic matter cycling and increase soil carbon and nutrient content. Although soil microbes play crucial roles in regulating soil biogeochemical processes, little is known about how mixed plantations affect soil microbial communities, including bacteria, archaea, and fungi. Here, we evaluated soil chemical properties, abundances and compositions of soil bacterial, archaeal, and fungal communities, and enzyme activities in pure and mixed Metasequoia glyptostroboides and Bischofia polycarpa plantations, located in Shanghai, China. The results showed that soil available phosphorus content in the mixed plantation of M. glyptostroboides and B. polycarpa was significantly higher than that in pure plantations, while no significant difference was observed in the content of soil organic carbon, total and available nitrogen, total and available potassium among the three studied plantations. We found higher fungal abundance in the mixed plantation, when compared to both pure plantations. Moreover, fungal abundance was positively correlated with the content of soil available phosphorus. No significant difference was found in the abundance and diversity of bacterial and archaeal community among the three studied plantations. A similarity analysis (ANOSIM) showed that mixed plantation significantly altered the community composition of archaea and fungi, accompanied with an increase of alkaline phosphatase activity. However, ANOSIM analysis of bacterial communities showed that there was no significant group separation among different plantations. Overall, results from this study indicated that fungal and archaeal communities were more sensitive to aboveground tree species than bacterial community. Moreover, mixed plantations significantly increased the activity of alkaline phosphatase and the content of soil available phosphorus, suggesting that afforestation with M. glyptostroboides and B. polycarpa is an effective way to alleviate phosphorus deficiency in urban forests in Shanghai, China.

Diversity patterns and drivers of soil microbial communities in urban and suburban park soils of Shanghai, China.

BACKGROUND: The rapid expansion of urbanization leads to significant losses of soil ecological functions. Microbes directly participate in key soil processes and play crucial roles in maintaining soil functions. However, we still have a limited understanding of underlying mechanisms shaping microbial communities and the interactions among microbial taxa in park soils. METHODS: In this study, the community variations of bacteria and fungi in urban and suburban park soils were investigated in Shanghai, China. Real-time PCR and high-throughput Illumina sequencing were used to examine the microbial abundance and community composition, respectively. RESULTS: The results showed that soil molecular biomass and fungal abundance in urban park soils were significantly higher than those in suburban park soils, while no significant difference was observed in the bacterial abundance between urban and suburban park soils. The alpha diversity of soil microbes in urban and suburban park soils was similar to each other, except for Chao1 index of fungal communities. The results of similarity analysis (ANOSIM) revealed remarkable differences in the composition of bacterial and fungal communities between urban and suburban park soils. Specifically, park soils in urban areas were enriched with the phyla Methylomirabilota and Verrucomicrobiota, while the relative abundance of Gemmatimonadota was higher in suburban park soils. Moreover, the fungal class Eurotiomycetes was also enriched in urban park soils. Compared with suburban park soils, nodes and average paths of the bacterial and fungal networks were higher in urban park soils, but the number of module hubs and connectors of the bacterial networks and negative interactions among bacterial taxa were lower. Compared with suburban park soils, Acidobacteriota bacterium and Mortierellomycota fungus played more important roles in the ecological networks of urban park soils. Soil available zinc (Zn), available nitrogen (N), pH, and total potassium (K) significantly affected fungal community composition in park soils in Shanghai. Soil available Zn was also the most important factor affecting the bacterial community composition in this study. CONCLUSION: There were significant differences in the soil molecular biomass, fungal abundance, and the community composition and co-occurrence relations of both soil bacterial and fungal communities between urban and suburban park soils. Soil available Zn played an important part in shaping the structures of both the bacterial and fungal communities in park soils in Shanghai.

The intergenic region of Arabidopsis thaliana cab1 and cab2 divergent genes functions as a bidirectional promoter.

Genetic engineering plays a unique role in fundamental plant biology studies and in improving crop traits. These efforts often necessitate introduction and expression of multiple genes using promoters from a very limited repertoire. Current common practice of expressing multiple genes is the repeated use of the same or similar promoters. This practice causes more frequent transgene silencing due to a high degree of sequence homology and a greater chance of rearrangement among repeatedly used promoter sequences. Therefore, availability and use of natural bidirectional promoters to minimize gene silencing and achieve desirable expression pattern of transgenes is a critical issue in the field of plant genetic engineering. Here we describe the use of a single natural bidirectional promoter to drive the expression of two reporter genes in onion epidermal cells and in transgenic tobacco plants. We show that (1) the promoter drives the simultaneous expression of GUS and GFP reporter genes after transient expression and stable transformation, (2) the transcription is equally strong in both directions, (3) immediate upstream regions in each direction control transcription independently from each other, and (4) the reporter genes are expressed in leaves and stems but not in roots, as expected from the fact that the endogenous promoter controls the expression of two photosynthetic genes in Arabidopsis. Hence, use of bidirectional promoters in heterologous background provides a means to express multiple genes in transgenic plants and aids genetic engineering-based crop improvement.

Diversity of culturable bacteria isolated from root domains of moso bamboo (Phyllostachys edulis).

The distribution of culturable bacteria in the rhizosphere, rhizoplane, and interior root tissues of moso bamboo plants was investigated in this study. Of the 182 isolates showing different colony characteristics on Luria-Bertani and King B plates, 56 operational taxonomic units of 22 genera were identified by 16S ribosomal RNA gene sequence analysis. The majority of root endophytic bacteria were Proteobacteria (67.5%), while the majority of rhizospheric and rhizoplane bacteria were Firmicutes (66.3% and 70.4%, respectively). The most common genus in both the rhizosphere and on the rhizoplane was Bacillus (42.4% and 44.4%, respectively), while Burkholderia was the most common genus inside the roots, comprising 35.0% of the isolates from this root domain. The endophytic bacterial community was less diverse than the rhizoplane and rhizospheric bacterial communities. Members of Lysinibacillus, Bacillus, and Burkholderia were found in all three root domains, whereas many isolates were found in only a single domain. Our results show that the population diversity of culturable bacteria is abundant in the root domains of moso bamboo plants and that obvious differences exist among the rhizospheric, rhizoplane, and endophytic bacterial communities.

[Effects of changes in water status on soil microbes and their response mechanism: A review]. / æ°´åˆ†æ¡ä»¶å˜åŒ–å¯¹åœŸå£¤å¾®ç”Ÿç‰©çš„å½±å“åŠå ¶å“åº”æœºåˆ¶ç ”ç©¶è¿›å±•.

Soil microbes play essential roles in maintaining terrestrial ecosystem services. Soil moisture is a primary determinant of soil microbial activities and ecosystem functions, which may fluctuate dramatically with the altered precipitation patterns and extreme drought caused by the ongoing global climate change. Due to the distinct soil microbial tolerance and life-strategy approaches to drought stress and different water status, fluctuation of soil moisture has a direct impact on microbial activities and community structure, thereby profoundly affecting microbial-mediated processes and ecosystem functions. Thus, it is of great significance to understand the dynamics and mechanisms that underlie the microbial responses to soil water status. In this review, we summarized recent progress in the study of responses of soil microbial activities (e.g. soil respiration and enzyme activities) and community structure to soil water status. We summarized underlying microbial physiological and ecological mechanisms, particularly 1) the cellular physiological accommodation such as osmolyte accumulation, exopolysaccharide production and transition into dormant states, and 2) the ecological strategies such as stress-resistant gene transfer and functional redundancy. Therefore, this investigation on the underlying relationship between soil microbial assembly and ecosystem functions under different water status could further demonstrate the microbially-mediated soil biogeochemical processes and provide a theoretical basis for future research and modelling of terrestrial ecosystem responses to climate change.

[Cultivable microbial diversity at the rhizosphere of Phyllostachys pubescens].

OBJECTIVE: To obtain the information of the cultivable microbial population diversity at the rhizosphere of Phyllostachys pubescens. METHODS: We isolated strains from Tianmu Mountain and Jinyun Mountain by diluting plate counting method and analyzed the 16S rDNA sequence of the isolates. RESULTS: We obtained 51 and 31 strains with different morphological character of colonies from Tianmu Mountain and Jinyun Mountain separately. The 16S rDNA sequence analysis showed that they had similar microbial population diversity. There were 40% and 58% firmicutes, 36.7% and 10.52% actinobacteria, 10% and 5.26% alphaproteobacteria, 10% and 26.32% gammaproteobacteria at the rhizosphere of Phyllostachys pubescens from Tianmu Mountain and Jinyun Mountain separately. The dominant bacteria were the genera Bacillus in both two areas. CONCLUSION: The result showed that the cultivable microbial population diversity was abundant and there were some potential novel strains at the rhizosphere of Phyllostachys pubescens. Our research made it is possible to further investigate the function of the rhizosphere microbes and there interaction with the bamboo plant.

Chemical Composition Analysis, Sensory, and Feasibility Study of Tree Peony Seed.

Eight wild species in Sect. Moutan DC (tree peony) of the genus Paeonia grown in natural habitats and 1 cultivated specie were investigated to analyze their fatty acid and bioactive phenolic compound profiles. For fatty acid composition, P. ludlowii contained the lowest α-linolenic acid (27.68%) and P. jishanensis contained the highest (51.96 %) content of the 9 species. For phenolic compounds, P. qiui contained the highest resveratrol (2.12 mg/g), P. delavayi contained the highest ß-gentiobiosylpaeoniflorin (26.23 mg/g), and P. ostii contained the highest paeoniflorin (23.66 mg/g). P. ostii was selected to perform a feasibility study because of its relatively high level of α-linolenic acid 46.53%, low in ω-6 to ω-3 ratio of 1:2, and high level of the preferred bioactive phenolic compounds l including paeoniflorin and resveratrol. Physical pressing and refining process were conducted to obtain P. ostii seed oil. It exhibited bland sensory attributes described as slight grassy, very slight nutty, no painty or fishy aroma and slight grassy, slight nutty flavor with a very slight throat catch. Tocol results reported high level in tree peony seed oil 223.5 ± 13.65 mg/100 g with γ-tocopherol 70.1 ± 2.14 mg/100 g, and γ-tocotrienol 149.6 ± 15.83 mg/g. Because of the high total tocol, γ-tocopherol and γ-tocotrienol levels, and tree peony seed oil exhibited better oxidation stability than flaxseed oil even with similar α-linolenic acid levels. In addition, high levels of γ-tocopherol and γ-tocotrienol can introduce therapeutic effects such as antiinflammation and antioxidation. Therefore, this study showed that tree peony seed oil has a great potential to be used in edible oil, nutraceutical supplement, and other health care products.

Selection of Reference Genes for Quantitative Real-Time PCR during Flower Development in Tree Peony (Paeonia suffruticosa Andr.).

Tree peony (Paeonia suffruticosa) is a perennial plant indigenous to China known for its elegant and vibrantly colorful flowers. A few genes involved in petal pigmentation have been cloned in tree peony. However, to date, there have been few studies on the comparison and selection of stable reference genes for gene expression analysis by quantitative reverse-transcription PCR (qRT-PCR) in this species. In this study, 10 candidate reference genes were evaluated for the normalization of qRT-PCR in three tree peony cultivars. GAPDH and UBC were identified as the top two most stable reference genes in 'Feng Dan' and 'Xi Shi,' and EF-1α/UBC was recommended to be the best combination for 'Que Hao.' The expression stability of various reference genes differed across cultivars, suggesting that selection and validation of reliable reference genes for quantitative gene expression analysis was necessary not only for different species but also for different cultivars. The results provided a list of reference genes for further study on gene expression in P. suffruticosa. However, in any case, a preliminary check on the accuracy of the best performing reference genes is requested for each qRT-PCR experiment.