Gluten-starch microstructure analysis revealed the improvement mechanism of Triticeae on broomcorn millet (Panicum miliaceum L.)

Understanding the mechanism by which Triticeae improves the quality of broomcorn millet (BM) is key to expanding the use of this crop to address food crises and food security. This study aimed to explore the effects of Triticeae on the disulfide bonds, secondary structures, microstructure, and rheological properties of BM dough, and to investigate the potential food applications of BM. Gluten protein, intermolecular SS, and β-Sheets content of the reconstituted doughs were significantly improved compared with BM dough, which improved disorderly accumulation of starch and gluten-starch interaction in BM dough. CLSM analysis showed that broomcorn millet-common wheat (BM-CW) and broomcorn millet-durum wheat (BM-DW) also possessed larger protein areas, smaller lacunarities, and better gluten-starch interactions in the reconstituted doughs. Disulfide bonds were positively correlated with the gluten network structure, and more disulfide bonds were formed in BM-CW (3.86 μmol/g), which promoted stronger mechanical resistance in BM-CW. Therefore, the combination of BM flour with CW and DW flours had better dough elasticity and stability. Finally, a potential evaluation and optimization scheme for BM as a cooked wheaten food is proposed to improve the reference for future food security and dietary structure adjustment of residents.

Endogenous bioactive gibberellin/abscisic acids and enzyme activity synergistically promote the phytoremediation of alkaline soil by broomcorn millet (Panicum miliaceum L.)

Broomcorn millet (Panicum miliaceum L.), an important food crop, grows in arid and semi-arid areas that face soil saline-alkalization. To date, no studies have investigated the mechanisms by which broomcorn millet seeds respond to and tolerate alkali stress. In this study, six broomcorn millet genotypes (B102, B220, B269, B279, B289, and B297) were selected to explore the physiological and molecular mechanisms of alkali stress at the germination stage. The results showed that alkali stress delayed the germination of broomcorn millet, and α-amylase activity was positively correlated with the germination rate. After alkali stress, the genotypes with lower alkali damage rates exhibited stronger antioxidant defenses. Real-time polymerase chain reaction analysis showed that alkali stress downregulated gibberellic acid (GA) synthesis genes but upregulated GA inactivation and abscisic acid (ABA) synthesis genes. Similarly, seeds displayed lower GA concentrations and higher ABA concentrations after alkali stress. Therefore, the ratios of various GAs/ABA decreased within the range of 35.77% to approximately 96.45%. Additionally, genotypes associated with lower alkali damage rates had higher GA/ABA ratios. These findings indicate that the alkali tolerance of broomcorn millet at the germination stage may be attributed to higher GA/ABA ratios, higher α-amylase activity, and stronger antioxidant defense, which synergistically resist alkali stress. This study will contribute to molecular breeding aiming to enhance alkali-tolerance and restoration of alkaline soils.

Intercropping Alters the Soil Microbial Diversity and Community to Facilitate Nitrogen Assimilation: A Potential Mechanism for Increasing Proso Millet Grain Yield

Intercropping of cereals and legumes has been used in modern agricultural systems, and the soil microorganisms associated with legumes play a vital role in organic matter decomposition and nitrogen (N) fixation. This study investigated the effect of intercropping on the rhizosphere soil microbial composition and structure and how this interaction affects N absorption and utilization by plants to improve crop productivity. Experiments were conducted to analyze the rhizosphere soil microbial diversity and the relationship between microbial composition and N assimilation by proso millet (Panicum miliaceum L.) and mung bean (Vigna radiata L.) from 2017 to 2019. Four different intercropping row arrangements were evaluated, and individual plantings of proso millet and mung bean were used as controls. Microbial diversity and community composition were determined through Illumina sequencing of 16S rRNA and internal transcribed spacer (ITS) genes. The results indicated that intercropping increased N levels in the soil-plant system and this alteration was strongly dependent on changes in the microbial (bacterial and fungal) diversities and communities. The increase in bacterial alpha diversity and changes in unique operational taxonomic unit (OTU) numbers increased the soil N availability and plant N accumulation. Certain bacterial taxa (such as Proteobacteria) and fungal taxa (such as Ascomycota) were significantly altered under intercropping and showed positive responses to increased N assimilation. The average grain yield of intercropped proso millet increased by 13.9-50.1% compared to that of monoculture proso millet. Our data clearly showed that intercropping proso millet with mung bean altered the rhizosphere soil microbial diversity and community composition; thus, this intercropping system represents a potential mechanism for promoting N assimilation and increasing grain yield.