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Partial nitrification (PN) is an effective process for treating high-strength ammonium wastewater with a low COD/N (chemical oxygen demand/total nitrogen) ratio; this is because the cooperative interaction with denitrification or anammox can result in a reduction in aeration costs of approximately 25% and a reduction in the use of organic sources during biological nitrogen removal of 40%. However, the key functional microorganisms in the partial nitrification (PN) process are ammonia-oxidizing bacteria (AOB), which are autotrophic microorganisms that are influenced by carbon sources. Therefore, the COD/N ratio affects the performance of the PN process when treating high-strength ammonium wastewater. In this study, five sequence batch reactors were constructed and operated for 42 days; they were fed with synthetic high-strength ammonium wastewater (500 mg/L) with various COD/N ratios (at 0, 0.5, 1, 2, and 4). The results suggested that the PN process could be accomplished at COD/N ratios of 0 and 0.5, but its performance decreased significantly when the COD/N ratio increased to 1 due to the occurrence of simultaneous nitrification and denitrification. The AOB could not compete with the heterotrophic bacteria; as the COD/N ratios increased, the abundance of Nitrosomonas (a genus of autotrophic AOB) decreased, and it was not detected at COD/N ratios of 2 and 4. Instead, the heterotrophic nitrification and heterotrophic denitrification (HNAD) bacteria appeared, and their relative abundance increased when the COD/N ratios increased from 1 to 4. [ABSTRACT FROM AUTHOR]

Summary: T. HALOPHILA HOMEOBOX PROTEIN 1(TsHD1) cloned from the halophyte Thellungiella halophila is a homeodomain (HD) transcription factor gene and functions as a collaborator of TsNAC1. TsHD1 can form heterodimers with TsNAC1 via the interaction between its zinc finger (ZF) domain and the A subdomain of TsNAC1. The overexpression of TsHD1 improved the heat stress resistance of T. halophila and retarded its vegetative growth slightly. The co‐overexpression of TsHD1 and TsNAC1 highly improved heat and drought stress resistance by increasing the accumulation of heat shock proteins and enhancing the expression levels of drought stress response genes, such as MYB DOMAIN PROTEIN 77 and MYB DOMAIN PROTEIN 96 (MYB77and MYB96) and SALT TOLERANCE ZINC FINGER 10 and SALT TOLERANCE ZINC FINGER 18 (ZAT10 and ZAT18), but seriously retarded the vegetative growth of T. halophila by restraining cell expansion. The heterodimer of TsHD1 and TsNAC1 has higher transcriptional activation activity and higher stability compared with the homodimer of TsHD1 or TsNAC1. The binding sites of the TsHD1 and TsNAC1 heterodimers were found to exist in the promoters of most upregulated genes in Cauliflower mosaic virus 35S promoter (P35S)::TsHD1 and P35S::TsNAC1 transgene lines compared with the wild type using RNA‐seq and genomic data analyses. Moreover, the binding sites in the promoter region of the most downregulated genes were located in the vicinity of the TATA‐box. This study reveals that TsNAC1 and TsHD1 play roles in plant growth and abiotic stress resistance synergistically, and the effects depend on the heterodimer binding to the specific target sites in the promoter region. Significance Statement: It is important to understand the relationship between plant growth and abiotic stress resistance for crop genetic improvement. Heterodimers of the transcription factors TsNAC1 and TsHD1 play important roles in plant growth and abiotic stress resistance. By contrast with the overexpression lines of TsNAC1, overexpressed TsHD1 retards plant growth slightly and significantly improves heat stress tolerance. This study examined the interaction model of TsNAC1 and TsHD1 and sought to determine their mechanisms using an RNA‐seq, gene expression assay and cis‐acting elements distribution analysis. [ABSTRACT FROM AUTHOR]

Heterologous expression of a transcription factor (TF) gene in a related species is a useful method for crop breeding and the identification of gene function. The differences in phenotype and target gene expression between HE lines (with the heterologous expression of an ortholog) and OX lines (with an overexpressed native gene) must be understood. EsNAC1 , encoding a NAC protein and the ortholog of RD26 in Arabidopsis , was cloned from Eutrema salsugineum and introduced into Arabidopsis. The heterologous expression of EsNAC1 retarded the vegetative growth of Arabidopsis , and the transgenic plants (HE lines) showed much greater resistance to salt and oxidative stress than the wild type, Col-0. The HE lines accumulated 2.8-fold (8-h light) of starch, 1.42-fold of Chlorophyll a and 1.31-fold of Chlorophyll b than Col-0 during the light period, with obvious differences compared to the RD26OX line. A genome-wide ChIP (chromatin immunoprecipitation analysis)-on-chip assay revealed that EsNAC1 targeted promoters of different genes compared to RD26. In HE lines, EsNAC1 could specifically upregulate the expression level of TF genes NAC DOMAIN CONTAINING PROTEIN 62 (ANAC062), INTEGRASE-TYPE DNA-BINDING PROTEIN (TINY2) , and MYB HYPOCOTYL ELONGATION-RELATED (MYBH) to show more effective abiotic stress resistance than RD26OX lines. Moreover, DELTA1-PYRROLINE-5-CARBOXYLATE SYNTHASE 1 (P5CS1), TRYPTOPHAN BIOSYNTHESIS 2 (TRP2) or GALACTINOL SYNTHASE 2 (GOLS2) , was also specifically regulated by EsNAC1 to retard the vegetative growth of HE lines, but not the brassinosteroid singling pathway in RD26OX lines. These differences in phenotypes and metabolism between the HE lines and the RD26OX line implied that the differential features could be produced from the diversity of target genes in the transgenic plants when the ortholog was introduced. [ABSTRACT FROM AUTHOR]

Summary: Maize is a globally important food, feed crop and raw material for the food and energy industry. Plant architecture optimization plays important roles in maize yield improvement. PIN‐FORMED (PIN) proteins are important for regulating auxin spatiotemporal asymmetric distribution in multiple plant developmental processes. In this study, ZmPIN1a overexpression in maize increased the number of lateral roots and inhibited their elongation, forming a developed root system with longer seminal roots and denser lateral roots. ZmPIN1a overexpression reduced plant height, internode length and ear height. This modification of the maize phenotype increased the yield under high‐density cultivation conditions, and the developed root system improved plant resistance to drought, lodging and a low‐phosphate environment. IAA concentration, transport capacity determination and application of external IAA indicated that ZmPIN1a overexpression led to increased IAA transport from shoot to root. The increase in auxin in the root enabled the plant to allocate more carbohydrates to the roots, enhanced the growth of the root and improved plant resistance to environmental stress. These findings demonstrate that maize plant architecture can be improved by root breeding to create an ideal phenotype for further yield increases. [ABSTRACT FROM AUTHOR]

Anammox is a novel and efficient nitrogen removal technique, while the long start-up time limits its industrial application, thus carriers are always utilized to accelerate its start-ups. Meanwhile, the preservation of anammox bacteria is a key element in its application. Therefore, it is also quite significant to evaluate the effect of carriers in reactivation of the anammox process after preservation. Through addition of polyurethane sponge in the upflow anaerobic sludge blanket (UASB) reactor (R 1), comparing with the one without polyurethane sponge addition (R 2), the time for anammox start-up was shorten by 28%, and the reactivation time was reduced by 50%. The preservation in 4 ℃ did not significantly affect the survival of anammox bacteria, but significantly decreased their nitrogen removal rate (NRR). Moreover, during the preservation, the decomposed EPS in R 1 (44%) was less compared to that in R 2 (66%). It took 36 days for R 1 to recover the NRR (0.084 kg·N·m-3·d-1), but took 60 days for R 2. At the end of reactivation, the abundance of Candidatus (Ca.) Brocadia and Ca. Kuenenia (both are anammox bacteria) was 4.5% and 2.7%, respectively, in R 1 , whereas there was no identified Ca. Kuenenia and the Ca. Brocadia was only 0.2% in R 2. Therefore, the addition of polyurethane sponge could short the start-up and reactivation time for anammox process by retaining more anammox bacteria in the reactor. [Display omitted] • Polyurethane sponge reduced start-up time by 28%. • Reactivation time was also reduced by 50%. • Preservation in 4 ℃ decreased NRR significantly. • Both Candidatus Brocadia (4.5%) and Candidatus Kuenenia (2.7%) were in R 1. • Only Candidatus Brocadia (0.2%) was in R 2. [ABSTRACT FROM AUTHOR]