Search

The NAC transcription factors play an important regulatory role in plant growth and development. In order to explore the impact of NAC6 on carotenoid metabolism in postharvest mango fruit, this study investigated changes in the carotenoid contents as well as the expression of NAC6 and key enzymes involved in carotenoid synthesis and metabolism in the mature peel and pulp of 2 mango varieties, “Tainong” and “Jinhuang”, at commercial maturity, during postharvest storage under constant temperature (20 ℃), constant humidity (85%), and dark conditions. The results showed that both mango varieties contained α-carotene, lutein, β-carotene, β-cryptoxanthin, and zeaxanthin. Throughout the storage process, the expression of NAC6 in both mango varieties showed a continuous upward trend, reaching a peak in the late stage of storage, followed by a slight decline. Correlation analysis showed that NAC6 might induce the gene expression of 1-deoxy-D-xylulose-5-phosphate reductoisomerase, farnesyl pyrophosphate synthase, geranylgeranyl pyrophosphate synthase, phytoene synthase, phytoene desaturase, ζ-carotene desaturase, carotenoid isomerase, β-carotene hydroxylase, and violaxanthin de-epoxidase in mango fruit, while inhibiting the gene expression of lycopene β-cyclase, neoxanthin synthase, and 9-cis-epoxycarotenoid dioxygenase. The expression of NAC6 in the peel and pulp of “Tainong” mango was significantly negatively correlated with the gene expression of carotenoid cleavage dioxygenase (CCD), with correlation coefficients of −0.841 0 and −0.838 3, respectively. NAC6 might delay the degradation of carotenoids by inhibiting the expression of CCD. The results from this research provide an experimental basis for the postharvest storage and preservation of mango fruit as well as its quality control.

【Background and objective】 Saline-alkali soils are widely distributed in Ningxia. Because of the scarcity of precipitation, such soils are often reclaimed by flooding rice field combined with subsurface drain. This paper presents the results of an experimental study of water and salt movement in a paddy field as affected by the sand filter in the subsurface drain. 【Method】 The field experiment was designed based on our current understanding and previous experimental results of the subsurface drains in different regions across the province. The experiment compared three filters: fine sand, mixture of fine sand and fine gravel sand at 1∶2 ratio and fine gravel. In each treatment, we measured spatiotemporal dynamics of soil water and soil salt. 【Result】 The filter with mixture of fine sand and fine gravel at 1∶2 ratio effectively reduced water content in the top 0~60 cm soil, increasing soil desalination during irrigation period as a result. Decrease in water content in the top 0~60 cm soil reduced evaporation, thereby alleviating salt accumulation in the root zone and reliveing salt stress to the crop. 【Conclusion】 The most effective filter for the subsurface drain in the studied paddy field is a mixture of fine sand and fine gavel at 1∶2 ratio.

In the face of the fossil energy crisis, hydrogen energy has attracted widespread attention because of its cleanness and efficiency. Therefore, hydrogen production by water electrolysis has become a new research upsurge. This research mainly focused on the synthesis, characterization and application of Pt/Cu alloy catalyst. Pt/Cu alloy was synthesized by solvothermal method. The composition, structure and morphology of Pt/Cu alloy were characterized by XRD, SEM, TEM, EDS, XPS, etc, to explore the relationship between its structure and performance. The catalytic performance of Pt/Cu alloy under different electrolyte were tested by electrochemical test system. In 0. 5 mol/L H2SO4, the initial overpotential of Pt/Cu alloy is 20. 3 mV (at 10 mA ⋅ cm-2) and the Tafel is 37.56 mV ⋅ dec-1. At the same time, the initial overpotential and Tafel of Pt/Cu alloy are 35.0 mV (at 10 mA ⋅ cm-2) and 52. 12 mV ⋅ dec-1 respectively in 1 mol/L phosphate buffered saline (PBS). In addition, the initial overpotential and the Tafel of Pt/Cu alloy are 25. 3 mV (at 10 mA ⋅ cm-2) and 36. 82 mV ⋅ dec-1 respectively in 1 mol/L KOH. It can be found that Pt/Cu alloy exhibits better catalytic performance in acidic electrolyte. Moreover, further experiments show that the Pt/Cu alloy catalyst has high electrocatalytic activity surface area (30. 83 cm²) and good cycle stability in acidic electrolyte. [ABSTRACT FROM AUTHOR]