Effects of foliar selenium application on growth and rhizospheric soil micro-ecological environment of Atractylodes macrocephala Koidz

Comprehensive evaluation of factors influencing selenium fertilization biofortification

BACKGROUND

Dietary selenium (Se) deficiency, stemming from low Se concentrations in agricultural products, threatens human health. While Se-containing fertilizers can enhance the Se content in crops, the key factors governing Se biofortification with Se fertilization remain unclear.

RESULTS

This study constructed a global meta-analysis dataset based on field experiments comprising 364 entries on Se content in agricultural products and 271 entries on their yield. Random forest models and mixed effects meta-analyses revealed that plant types (i.e., cereals, vegetables, legumes, and forages) primarily influenced Se biofortification, with Se fertilization rates being the next significant factor. The random forest model, which included variables like plant types, Se fertilization rates, methods and types of Se application, initial soil conditions (including Se content, organic carbon content, and pH), soil types, mean annual precipitation, and temperature, explained 82.14% of the variation in Se content and 48.42% of the yield variation in agricultural products. For the same agricultural products, the increase in Se content decreased with higher rates of Se fertilization. The increase in Se content in their edible parts will be negligible for cereals, forages, legumes, and vegetable crops, when Se fertilization rates were 164, 103, 144, and 147 g Se ha-1, respectively. Conversely, while low Se fertilization rates enhanced yields, high rates led to a yield reduction, particularly in cereals.

CONCLUSION

Our findings highlight the need for balanced and precise Se fertilization strategies to optimize Se biofortification benefits and minimize the risk of yield reduction. © 2024 Society of Chemical Industry.

Combined transcriptome and metabolome analyses reveal the effects of selenium on the growth and quality of Lilium lancifolium

Lilium lancifolium Thunb (L. lancifolium) is an important medicinal and edible plant with outstanding functionality for selenium (Se) biofortification. However, the molecular response of L. lancifolium to exogenous Se has not been fully elucidated. In this study, the effects of different levels of Se on L. lancifolium growth and quality were explored by transcriptome, metabolome and biochemical analyses. The results showed that the total Se and organic Se content in L. lancifolium bulbs increased with increasing Se dosage (0-8.0 mmol/L). Moreover, Se stimulated the growth of L. lancifolium at low level (2.0 mmol/L) but showed an inhibitory effect at high levels (≥4.0 mmol/L). Metabolomic and biochemical analyses revealed that the bulb weight and the content of amino acid, soluble sugar, and soluble protein were significantly increased in the 2.0 mmol/L Se treatment compared with those in the control (0 mmol/L Se). Transcriptome and metabolome analyses revealed that the significant upregulation of the GPD1, GPAT and ADPRM genes promoted glycerophospholipid accumulation. Additionally, the significantly upregulated glyA and downregulated asnB, nadB, thrA and SAT genes coordinate to the regulation of amino acid biosynthesis. The significantly upregulated SUS, bgl B, BAM, and SGA1 genes were involved in soluble sugar accumulation under Se treatment. In summary, this study identified the optimal Se concentration (2.0 mmol/L), which significantly improved the growth and nutritional quality of L. lancifolium and contributed to understanding the combined effects of Se treatment on the expression of genes and the accumulation of metabolites in L. lancifolium bulbs.

Silica and Selenium Nanoparticles Attract or Repel Scale Insects by Altering Physicochemical Leaf Traits

Although nanoparticles have gained attention as efficient alternatives to conventional agricultural chemicals, there is limited knowledge regarding their effects on herbivorous insect behavior and plant physicochemistry. Here, we investigated the effects of foliar applications of nano-silica (SiO2NPs) and nano-selenium (SeNPs), and bulk-size silica (SiO2) on the choice behavior of the arrowhead scale insect on mandarin orange plants. One leaf of a bifoliate pair was treated with one of the three chemicals, while the other was treated with water (control). The respective SiO2, SeO2, calcium (Ca), and carbon (C) content levels in the leaf epidermis and mesophyll were quantified using SEM-EDX (or SEM-EDS); leaf toughness and the arrowhead scale density and body size were measured. First-instar nymphs preferred silica-treated leaves and avoided SeNP-treated leaves. SiO2 content did not differ between control and SiO2NP-treated leaves, but was higher in bulk-size SiO2-treated leaves. The SiO2 level in the control leaves was higher in the SiO2NP treatment compared with that in the control leaves in the bulk-size SiO2 treatment. Silica-treated leaves increased in toughness, but SeNP-treated leaves did not; leaf toughness increased with mesophyllic SiO2 content. The insect density per leaf increased with leaf toughness, SiO2 content and, in the SiO2NP treatment, with epidermal C content. There was no correlation between SeO2 content and insect density. This study highlights the potential uses of SeNPs as an insect deterrent and of silica for enhancing leaf toughness and attracting scale insects.

Diversity and structural analysis of rhizosphere soil microbial communities in wild and cultivated Rhizoma Atractylodis Macrocephalae and their effects on the accumulation of active components

Rhizosphere microorganisms are the main factors affecting the formation of high quality medicinal materials and promoting the accumulation of secondary metabolites. However, the composition, diversity, and function of rhizosphere microbial communities in endangered wild and cultivated Rhizoma Atractylodis Macrocephalae (RAM) and their relationships with active component accumulation have remained unclear. In this study, high-throughput sequencing and correlation analysis were used to study the rhizosphere microbial community diversity (bacteria and fungi) of three RAM species and its correlation with the accumulation of polysaccharides, atractylone, and lactones (I, II, and III). A total of 24 phyla, 46 classes, and 110 genera were detected. The dominant taxa were Proteobacteria, Ascomycota, and Basidiomycota. The microbial communities in both wild and artificially cultivated soil samples were extremely species-rich, but there were some differences in their structure and the relative abundances of microorganism taxa. Meanwhile, the contents of effective components in wild RAM were significantly higher than those in cultivated RAM. Correlation analysis showed that 16 bacterial and 10 fungal genera were positively or negatively correlated with active ingredient accumulation. These results showed that rhizosphere microorganisms could play an important role in component accumulation and might lay a foundation for future research on endangered materials.

Foliar application of nutrients on medicinal and aromatic plants, the sustainable approaches for higher and better production

Background

The most important advantages of foliar fertilization are to improve plant growth and crop quality, appropriately manage the nutritional status of plants, enhance disease resistance and regulate nutrient deficiencies.

Main body

The aim of this manuscript is to outline and emphasize the importance of foliar application of nutrients in order to increase both quality and yield of medicinal and aromatic plants. The searches focused on publications from 1980 to July 2021 using PubMed, Google Scholar, Science Direct and Scopus databases. The current manuscript presented many examples of potential of foliar application for medicinal and aromatic plants production systems. Foliar application of Fe and Zn on Anise; Se on Atractylodes; Zn sulfate on Basil, Costmary, Mint and Fenugreek; Se and Fe on Stevia; S and P on castor bean; Zn and Fe on Chamomile; Cu, Mg and ZnSO4 on Damask rose; N and P on Fennel; Se on water spinach and tea; K+ and Ca2+ on Thyme; Zn and K on Spearmint; Zn on Saffron, Ni on Pot marigold; Fe on peppermint, N and P on Mustard had positive and significant impacts.

Conclusion

Observed impacts of foliar fertilization consisted of significant increase of yield, enhanced resistance to insects, pests and diseases, improved drought tolerance and escalated crop quality.

Transcriptomic Characterization of the Effects of Selenium on Maize Seedling Growth

Selenium (Se) is a trace mineral element in soils that can be beneficial to plants in small amounts. Although maize is among the most economically important crops, there are few reports on the effects of Se on maize seedling growth at the molecular level. In this study, the growth of maize seedlings treated with different concentrations of Na₂SeO₃ was investigated, and the physiological characteristics were measured. Compared with the control, a low Se concentration promoted seedling growth, whereas a high Se concentration inhibited it. To illustrate the transcriptional effects of Se on maize seedling growth, samples from control plants and those treated with low or high concentrations of Se were subjected to RNA sequencing. The differentially expressed gene (DEG) analysis revealed that there were 239 upregulated and 106 downregulated genes in the low Se treatment groups, while there were 845 upregulated and 1,686 downregulated DEGs in the high Se treatment groups. Both the Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation analyses showed a low concentration of the Se-stimulated expression of "DNA replication" and "glutathione (GSH) metabolism"-related genes. A high concentration of Se repressed the expression of auxin signal transduction and lignin biosynthesis-related genes. The real-time quantitative reverse transcription PCR (qRT-PCR) results showed that in the low Se treatment, "auxin signal transduction," "DNA replication," and lignin biosynthesis-related genes were upregulated 1.4- to 57.68-fold compared to the control, while, in the high Se concentration treatment, auxin signal transduction and lignin biosynthesis-related genes were downregulated 1.6- to 16.23-fold compared to the control. Based on these transcriptional differences and qRT-PCR validation, it was found that a low dosage of Se may promote maize seedling growth but becomes inhibitory to growth at higher concentrations. This study lays a foundation for the mechanisms underlying the effects of Se on maize seedling growth.