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Background Glucose can be involved in metabolic activities as a structural substance or signaling molecule and plays an important regulatory role in fruit development. Glucose metabolism is closely related to the phenylpropanoid pathway, but the specific role of glucose in regulating lignin biosynthesis in pear fruit is still unclear. The transcriptome of pear calli generated from fruit and treated with glucose was analyzed to investigate the role of glucose in lignin biosynthesis. Results The treatment of exogenous glucose significantly enhanced the accumulation of lignin in pear calli. A total of 6566 differentially expressed genes were obtained by transcriptome sequencing. Glycolysis was found to be the pathway with significant changes. Many differentially expressed genes were enriched in secondary metabolic pathways, especially the phenylpropanoid pathway. Expression of structural genes (PbPAL, PbHCT, PbCOMT, PbPRX) in lignin biosynthesis was up-regulated after glucose treatment. In addition, glucose might regulate lignin biosynthesis through interactions with ABA, GA, and SA signaling. Several candidate MYB transcription factors involved in glucose-induced lignin biosynthesis have also been revealed. The qRT-PCR analyses showed that the expression pattern of PbPFP at early developmental stage in ‘Dangshansuli’ fruits was consistent with the trend of lignin content. Transient expression of PbPFP resulted in a significant increase of lignin content in ‘Dangshansuli’ fruits at 35 days after full bloom (DAB) and tobacco leaves, indicating that PbPFP (Pbr015118.1) might be associated with the enhancement of lignin biosynthesis in response to glucose treatment. Conclusions PbPFP plays a positive role in regulating lignin biosynthesis in response to glucose treatment. This study may reveal the regulatory pathway related to lignin accumulation in pear calli induced by glucose.

Light environment is an indispensable factor that regulates multitudinous developmental processes during the whole life cycle of plants, including fruit development. Stone cells which negatively influence pear fruit quality because of their strongly lignified cell wall are also affected by light, however, how light qualities influence lignin biosynthesis in pear remains unclear. Here, the calli of European pear (Pyrus communis L.) treated with different lights were used to explore the changes in phenotype, lignin content, and H

On the premise of maximizing nitrogen elimination in wastewater and recharging the effluent directly to groundwater, two groups of subsurface wastewater infiltration systems (SWIS), a turfgrass-covered system (S-G) and a bare soil system (S-B), were examined under a pollution load of 600 kg N ha−1 yr−1 to investigate the contribution of turfgrass in removing sewage nitrogen. The results showed that compared with S-B, the concentrations of total nitrogen (TN) and nitrate nitrogen (NO3−-N) in S-G effluent were significantly lower. In 2014 and 2015, the average concentrations of NO3−-N in S-B effluent were 38.9 and 36.8 mg L−1. None of the NO3−-N concentrations in S-B effluent satisfied the international standard for drinking water (10 mg L−1 NO3−-N). While the average concentrations of NO3−-N in S-G effluent in 2014 and 2015 were 2.96 and 0.80 mg L−1, the proportions of NO3−-N concentrations in S-G effluent, which were below 10 mg L−1 NO3−-N, were 87.7% and 97.9%, respectively. The TN removal efficiency and removal quantity of the S-G were significantly higher than those of the S-B. In 2014 and 2015, the TN removal quantities of S-G were 646 and 647 kg ha−1 yr−1, respectively, and the TN removal efficiencies reached 98.1% and 99.1%, for which the contribution efficiencies of turfgrass on nitrogen removal were 52.5% and 61.0%, respectively. Meanwhile, the TN removal quantities of S-B were 269 and 204 kg ha−1 yr−1, and the TN removal efficiencies were 40.7% and 31.3% in 2014 and 2015, respectively. These obtained results indicated that plants play an important role in SWIS under these conditions.

To improve the performance and overcome the processing difficulties of La0.99Ca0.01NbO4 proton-conducting ceramic oxide, external and internal strategies were used, respectively, to modify La0.99Ca0.01NbO4 with NiO. The external strategy refers to the use of the NiO as a sintering aid. The NiO was added to the synthesized La0.99Ca0.01NbO4 powder as a secondary phase, which is the traditional way of using the NiO sintering aid. The internal strategy refers to the use of NiO as a dopant for the La0.99Ca0.01NbO4. Both strategies improve the sinterability and conductivity, but the effect of internal doping is more significant in enhancing both grain growth and conductivity, making it more desirable for practical applications. Subsequently, the influences of different concentrations of NiO were compared to explore the optimal ratio of the NiO as the dopant. It was found that the sample with 1 or 2 wt.% NiO had similar performance, while with 5 wt.%, NiO doping content hampered the grain growth. In addition, the inhomogeneous distribution of the element in the high-NiO content sample was found to be detrimental to the electrochemical performance, suggesting that the moderate doping strategy is suitable for La0.99Ca0.01NbO4 proton-conducting electrolyte with improved performance. Furthermore, first-principle calculations indicate the origin of the enhanced performance of the internally modified sample, as it lowers both oxygen formation energy and hydration energy compared with the un-modified one, facilitating proton migration.