Magnesium (Mg) deficiency, a widespread yet overlooked problem in agriculture, has been reported to retard plant growth and development, through affecting key metabolic pathways. However, the metabolic responses of plant to Mg deficiency is still not fully understood. Here we report a metabolomic study to evaluate the metabolic responses to Mg deficiency in soybean leaves and roots. Hydroponic grown soybean were exposed to Mg starvation for 4 and 8 days, respectively. Metabolic changes in the first mature trifoliolate leaves and roots were quantified by conducting GC-TOF-MS based metabolomic analysis. Principal component analysis (PCA) showed that Mg deficient plants became distinguishable from controls at 4 days after stress (DAS) at metabolic level, and were clearly discriminated at 8 DAS. Mg deficiency could cause large metabolite alterations on carbon and nitrogen metabolism. At 8 DAS, carbon allocation from shoot to root is decreased by Mg deficiency. Remarkably, most amino acids (such as phenylalanine, asparagine, leucine, isoleucine, glycine, glutamine, and serine) showed pronounced accumulation in the leaves, while most organic acids (including pyruvic acid, citric acid, 2-keto-glutaric acid, succinic acid, fumaric acid, and malic acid) were significantly decreased in the roots. Our study shows that the carbon and nitrogen metabolic responses are distinct in leaves and roots under Mg deficiency.

In a 2 yr field experiment, we investigated the combined effects of reduced nitrogen (N) rate and increased plant density on the trade-off between the grain protein content (GPC) and the grain yield (GY) in soft wheat cultivars. Reducing N application significantly decreased both GPC and GY; however, to some extent, increasing the top-dressed N ratio and plant density compensated for the GY loss. Optimizing the combination of these three factors (150 kg N ha–1 with 50% top-dressed N and 360 × 104 plants ha–1) achieved both the required lower GPC for soft wheat and relatively higher GY compared with the conventional cultivation strategy. In addition, this optimized combination downregulated 11 high-molecular-weight glutenin subunits, 8 low-molecular-weight glutenin subunits, 5 α/β-gliadins, and 2 γ-gliadins in mature grains as identified by data-independent acquisition mass spectrometry. Further analysis indicated that the relatively lower free amino acid content and downregulated expressions of the seed storage protein (SSP) synthesis-related genes in filling grains contributed to the reduction of SSP and GPC. Furthermore, the dilution effect induced by a relatively higher accumulation of starch than proteins also partially explained the reduced GPC. Unlike proteins, grain starch accumulation and content depended more on the soluble sugar availability, rather than on the starch synthesis capacity. These findings provide novel insights on simultaneous improvement in the grain quality and yield of soft wheat through synchronized manipulations of N fertilization and plant density.

A set of high-molecular-weight glutenin subunit (HMW-GS) deletion lines were used to investigate the influences of HMW-GS on wheat gluten, and dough properties were investigated using a set of HMW-GS deletion lines. Results showed that HMW-GS deletion significantly decreased the dough stability time, as well as viscoelastic moduli (G′ and G″), compared with the wild type, where the deletion of x-type HMW-GSs (Ax1d, Bx7d, and Dy12d) decreased more than y-type HMW-GSs (By8d and Dy12d). The deletion of HMW-GS significantly decreased HMW-GS contents and increased α-/γ-gliadin contents. A proteomic study showed that the HMW-GS deletion down-regulated the HMW-GS, β-amylase, serpins, and protein disulfide isomerase and up-regulated the LMW-GS, α/γ-gliadin, and α-amylase inhibitor. Meanwhile, HMW-GS deletion significantly decreased contents of β-turn and β-sheet. In addition, less energetically stable disulfide conformations (trans–gauche–gauche and trans–gauche–trans) were abundant in HMW-GS deletion lines. Furthermore, analysis of five HMW-GSs based on amino acid sequences proved that Dx2 and Bx7 had a more stable structure, followed by Ax1, then Dy12, and finally By8.

Organic acid and rust remover based on citric acid were gradually praised by the industry because of its environmental protection and good derusting effect. In this paper, the production cycle of citric acid by Aspergillus Niger shaking flask fermentation was studied with Passion Fruit/Shell, and the rust removal effect of the product was preliminarily verified. The cultivation factors included Passion Fruit/Shell 20%+Sucrose 5%, 35°C, pH 5.0-5.5, shaking table 150 r/min, the fermentation cycle could be completed in 4-5 days, and the pH in fruit fermentation broth decreased to 2.7. At room temperature, the derusting effect of 1 time diluted fruit fermentation broth equaled that of 3%commercial citric acid, the rust removal time could prolonged properly at low temperature. The resultshad a guiding significance for producing organic rust remover from Passion Fruit by Aspergillus Niger.