New insights into molecular features of the genome-wide AOX family and their responses to various stresses in common wheat (Triticum aestivum L.).

Alternative oxidase (AOX) is an important terminal oxidase involved in the alternative oxidation pathway in plants, which is closely related to various biotic and abiotic stress responses. However, a comprehensive research on AOX gene family of wheat is still lacking. In this study, the members of wheat AOX (TaAOX) family were identified, and their molecular characteristics and gene expression patterns were systematically investigated. Seventeen TaAOX genes were identified from Chinese Spring (CS) genome, which were mapped on 7 chromosomes and mainly clustered on the long arm's distal end of the second homologous groups. Phylogenetic analysis showed that TaAOX genes were classified into four subgroups (Ia, Ib, Ic, and Id), and the Ia subgroup possessed the most members. Tandem duplication and segmental duplication events were found during the evolution of TaAOX genes and they were affected by purifying selection demonstrated by Ka/Ks analysis. The exon numbers of this family gene varied greatly from 1 to 9. Except for Ta3BSAOX14, all the proteins encoded by the other 16 TaAOX genes contained the amino acid residues of the key active sites in the AOX domain (cd01053). The expression patterns of TaAOX genes in various tissues and under abiotic and biotic stresses were analyzed using public transcriptome data, furthermore, qRT-PCR analysis was performed for some selected TaAOX genes, and the results suggested that most members of this gene family play an important role in response to different stresses in common wheat. Our results provide basic information and valuable reference for further exploring the gene function of TaAOX family by using gene editing, RNAi, VIGS, and other technologies.

[Characteristics and Performance of Embedded ANAMMOX Bacteria in Treating Saline Wastewater].

In order to improve the mechanical stability of the material, the embedded raw material combination was studied in the experiment, and seawater was added to optimize the performance of the material. The results indicated that the optimal material ratio was polyvinyl alcohol (PVA 125 g·L-1)-alginate sodium (SA 20 g·L-1)-activated carbon (40 g·L-1). The curing time was 18 h. After adding seawater, the beads were found to have larger pore sizes inside, and the pores were distributed unevenly because of the Hofmeister effect. At the same time, the mechanical stability and biological capacity were found to be significantly higher than those of the fresh water group. The Raman spectra analysis showed that the addition of seawater made the-OH on PVA have greater crosslinking reactions with the crosslinker. The activated sludge was used to treat wastewater containing sea water, and after an operation of 21 d, the removal rate of NH4+-N was about 90%, and the stoichiometric ratio of △NH4+-N:△NO2--N:△NO3--N was stable at 1:(1.04±0.1):(0.17±0.02). From the 21st day to the 46th day, the reactor was run in a steady state. When the nitrogen load rate doubled, the ammonia nitrogen removal rate and stoichiometry had little variations. The total nitrogen removal rate was about 85%, and the total nitrogen removal load rate was 0.2 kg·(m3·d)-1.

[Migration and Transformation of Dissolved Organic Matter in Karst Water Systems and an Analysis of Their Influencing Factors].

Fluorescent substances are used as good tracers in dissolved organic matter (DOM) to identify the source of DOM and its geochemical behavior in a hydrological system. However, there are few studies on the karst aquifer system. Many parameters in karst systems affect the DOM spectral information. A typical karst watershed in Northern China was selected in this research. Excitation-emission matrices (EEMs), parallel factor analysis (PARAFAC), and hydrochemical data were applied to reveal the relationship between the composition and transformation of DOM fluorescent substances in different karst water-bearing spaces. The source of DOM and the effect of water chemistry on DOM transfer were also discussed. The results showed that DOM in exogenous surface water and karst surface water in the Yufu River watershed were mainly composed of tryptophan-like substances, while the DOM in shallow karst water and deep karst water consisted of tryptophan-like and tyrosine-like substances. A comprehensive analysis by fluorescence index (FI), biological index (BIX), and humification index (HIX) displayed that the DOM in shallow and deep karst water resulted from microbial decomposition. In contrast, the DOM in karst surface water and exogenous surface water resulted from land-based input and endogenous microbial decomposition, in which endogenous contributions occupy a large proportion. Due to the chemical parameters of karst water, these three kinds of fluorescent substances extracted by PARAFAC had obviously different characteristics, i.e., ① the tyrosine-like substances had a strong adaptability to Ca2+ and HCO3-, and the proportion of the tyrosine in karst water was relatively large; ② the tryptophan substance followed an opposite trend; and ③ there was a significant positive correlation between fulvic acid and TDS, turbidity, Cl-, and SO42-. Observations of the watershed runoff revealed that the DOM in shallow karst water in the upper reaches came mainly from the soil and microbial degradation. The organic matter underwent a large amount of microbial decomposition and exogenous input when the water was rejuvenated with springs. After infiltration to the deep karst water in the lower reaches, the DOM gradually were converted to low aromatic hydrocarbon organic compounds and decreased macromolecules of DOM. Subsequently, the fluorescence intensity was weakened. The principal component analysis (PCA) extracted three principal components. They were the water mineralization index, soil leaching index, and hydrochemical/biochemical process index. The water mineralization index consists of hydrochemical parameters reflecting the water infiltration, transformation, and flow conditions in the karst system. The soil leaching index contains TOC, NO3-, and protein-like indicators relating to the relationship between protein-like substances and soil and natural leaching. The hydrochemical/biochemical process index is composed of Ca2+, HCO3-, FI, and fulvic acid indicators that illustrate the water chemistry and biochemical processes in the karst water system. In addition, the study also showed that total fluorescence intensity, fulvate-like substances, and protein-like substances can be used as a tracer for rapid seepage, transformation, and aquifer fragility for karst water, respectively. The results of the study are important in understanding the biogeochemical cycle of DOM in the karst water system and also helpful for controlling organic pollution. It also provides a new tool for characterizing the geochemical processes of organic matter in karst system.

[Enrichment and Nitrogen Removal Characteristics of Marine Anaerobic Ammonium Oxidizing Bacteria].

In this work, enrichment and nitrogen removal characteristics of marine anaerobic ammonium oxidizing bacteria were investigated by seeding sediment sludge from the Jiaozhou bay. Experimental results showed that the whole process could be divided into four phases:bacterial lysis phase (1-15 d), lag phase (16-152 d), exponential growth phase (153-183 d) and stationary phase (184-192 d). Compared to freshwater anaerobic ammonium oxidizing bacteria, the lag phase (137 d) was longer. However, the exponential growth phase (30 d) was shorter. Besides, marine anaerobic ammonium oxidizing bacteria were more sensitive to variation in substrate concentration and HRT. The activity delay time caused by inflow and effluent was 5 h, which was far longer than fresh anaerobic ammonium oxidizing bacteria. As a result, the adaptive ability of marine anaerobic ammonium oxidizing bacteria was weaker and it was harder to enrich. After successful enrichment of 192 d, the removal rates of ammonia nitrogen and nitrite nitrogen were 96.98% and 95.66%, respectively. n(NH4+-N):n(NO2--N):n(NO3--N) was 1:(1.2±0.2):(0.22±0.06), which was close to the theoretical ratio. NRRNH4+-Nwas 0.080 kg·(m3·d)-1, which indicated that the activity of marine anaerobic ammonium oxidizing bacteria increased significantly. The enrichment of marine anaerobic ammonium oxidizing bacteria was achieved. The sludge characteristics changed from black to red. SEM observation confirmed that the red granule was cenobium, which consisted of closely spaced micrococcus with smooth surface and crateriform shape.