Chemical and Biological Technologies in Agriculture最新文献

The imperative use of pesticides for enhancing agricultural productivity has become inevitable. Unfortunately, the unregulated and indiscriminate application of these pesticides extends beyond the intended target areas, with residues persisting for months to even years. This lack of precision and information has triggered widespread pest outbreaks, posing significant health risks to both humans and other organisms due to pesticide residues in food. The presence of even trace amounts of these residues has emerged as a major impediment to international trade in food commodities. To address these challenges and align with sustainable practices, the article highlights the urgent need for controlled pesticide techniques, including organic farming, safe harvest indices, and bioremediation, which are crucial aspects of mitigating admixed micropollutants in the environment. The discussion covers the impact of pesticides on food quality, effective residue management, and the vital role of regulatory bodies. Drawing from diverse sources, the work seeks to provide a concise yet comprehensive overview and solutions to the challenges of pesticide management.

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Background

Stellaria dichotoma L. var. lanceolata Bge. (S. lanceolata) is a psammophytic plant endemic to the northwest region of China and has now developed into a cultivated economic crop. It is the original plant species used in traditional Chinese medicine as Yinchaihu. Recently, the lack of scientifically guided production zoning has exacerbated the arbitrary introduction and expansion of S. lanceolata cultivation, resulting in significant changes to its habitat and quality.

Methods

This study utilizes distribution data of wild S. lanceolata along with data from 33 environmental factors to analyze the primary habitat factors influencing the species' distribution using the Maxent model, simulating both current and future suitable production zones. Additionally, amplicon sequencing was employed to investigate changes in rhizospheric soil microorganisms across different cultivation sites and years. Furthermore, metabolomics, near-infrared spectroscopy, and the quantification of active ingredient content were used to assess the effects of various suitable zones on S. lanceolata.

Results

The migration trends of S. lanceolata toward the central and eastern regions of Inner Mongolia revealed that elev, bio_4, bio_13, bio_11, and S_clay are the primary ecological and soil factors influencing suitability zoning, contributing a cumulative rate of 80.5%. The rhizosphere microbial environment shifted significantly from high to medium suitability habitats. As cultivation duration increased, the diversity of fungi and bacteria and the functional genera within the rhizosphere exhibited significant changes. Notably, there were substantial alterations in metabolic processes and substance accumulation during the transition from high to medium and low suitability zones, resulting in the identification of 281 and 370 differential metabolites, respectively. Additionally, the near-infrared spectral characteristics and active ingredient content of S. lanceolata in high suitability zones displayed distinct specificity. In particular, the contents of total flavonoids (2.772 mg·g⁻¹), dichotomines B (0.057 mg·g⁻¹), and quercetin-3-O-β-D-glucoside (0.312 mg·g⁻¹) were notably higher, with the overall quality score surpassing that of other suitable zones.

Conclusion

This study revealed the key climatic, soil, and rhizosphere microbial environmental factors influencing the quality formation of S. lanceolata and the selection of suitable production zones, offering guidance for sustainable development and production zone planning.

Graphical Abstract

Background

There is an increasing interest in using lignocellulosic feedstocks for biogas production. Treatment of these feedstocks prior to anaerobic digestion (AD) can enhance their accessibility to microorganisms involved in the process. To improve the digestion of recalcitrant feedstocks and boost biogas yields, many biogas plants now employ two-step AD systems, extending substrate residence times. However, the combined effect of feedstock treatment and two-step AD on methane yield and fertiliser value of digestates are underexplored. This study, therefore, evaluated the effectiveness of thermal treatment (TT) of pre-digested agricultural feedstocks before a secondary AD step on the carbon (C) and nitrogen (N) dynamics of digestates following application to soil. It also investigated the effects of TT on methane yields. Pre-digested feedstock (PDF) was treated at three different temperatures (70 °C, 120 °C and 180 °C) for 60 min, followed by parallel secondary AD steps using lab-scale continuous stirred-tank reactors (CSTR) and a batch test. Thermally treated feedstocks with and without a secondary AD step were applied to soil to study C and N dynamics and turnover for 2 months.

Results

TT at 180 °C increased ultimate CH₄ yields by 7.2%; however, it decreased the net mineral N release in soil from 42 to 34% (of N input). Adding a secondary AD step increased the net mineral N release in soil from an average of 39% to 47% (of N input), with the effect of TT levelling off. Moreover, the secondary AD step significantly reduced C mineralisation rates from an average of 37% to 26% (of C applied).

Conclusions

Overall, TT at 120–180 °C can improve biogas yields of recalcitrant feedstocks, but it may lead to the formation of refractory nitrogen compounds resistant to further degradation during AD, potentially resulting in a lower N fertiliser value of digestates.

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Background

Bacterial wilt disease, caused by Ralstonia solanacearum, seriously threaten the quality and yield of peanut (Arachis hypogaea L.). Identification of proteins inducing host immune response in R. solanacearum is an important way towards exploring resistance genes in peanut. In previous study, we found that the pathogenicity was significant different between peanut R. solanacearum ZKRS126 and ZKRS146. In this study, comparative genomics analysis was performed to reveal the difference of the genomes between ZKRS126 and ZKRS146, as well as the function of the strain specific gene rsmA in triggering immunity.

Results

Compared with ZKRS146, ZKRS126 caused less cell death in the peanut leaves and its proliferation and pathogenicity were significantly attenuated. Whole genome sequencing revealed that the genomes of ZKRS126 and ZKRS146 were composed of one chromosome, one megaplasmid and one small plasmid. The genome size of ZKRS126 (6,059,912 bp) was slightly larger than that of ZKRS146 (6,053,081 bp). Comparative genomics analysis showed that the genetic relationship between ZKRS126 and ZKRS146 was very close. In both ZKRS126 and ZKRS146, 73 Type III secretion system-secreted effectors (T3Es) were identified by retrieving the effector repertoire, respectively. The gene sequences of T3Es were identical between ZKRS126 and ZKRS146. Comparing all the coding genes between ZKRS126 and ZKRS146, 42 specific genes were identified in ZKRS126 and 43 in ZKRS146. Loss of the specific gene rsmA in ZKRS126 resulted in more virulence, and complementarity of rsmA in mutant strains recovered hypovirulence. The cAMP assay demonstrated RsmA was not a T3E. In Nicotiania benthamiana leaves, transient expression of rsmA significantly induced the up-regulated expression of marker genes in HR, PTI, SA, and JA pathways, indicating RsmA might trigger the plant immunity by activating the immune-related pathways.

Conclusions

This study not only obtained the complete genomes of two peanut R. solanacearum strains, but also revealed their differences in the genome levels through comparing analysis. The function verification of RsmA provided the way for the identification of immunity elicitors, which will accelerate the breeding of bacterial wilt-resistant peanut varieties in the future.

Graphical Abstract

Background

CSPs are known for their complex and arguably obscure function(s), particularly in chemical olfaction. It is unclear which CSPs in Aleurocanthus spiniferus are involved in the identification of host VOCs. This study on A. spiniferus utilized gene expression, ligand binding, RNAi and molecular docking to determine the CSPs involved in the binding and transport of six host VOCs.

Results

Four (AspiCSP7, 9, 12 and 16) of the 12 CSPs underwent transcriptional up- or down-regulation after induction by host VOCs. AspiCSP16 can bind to six VOCs, and AspiCSP7 can bind to five except linalool. dsAspiCSP7-treated adults showed significantly lower tendency to 3-carene, hexanol, (E)-2-hexenal, and lost avoidance of (Z)-3-hexenol; the preference for 3-carene, hexanol, and the avoidance of nonanal and (Z)-3-hexenol were reduced when AspiCSP16 was knocked down. Although it is difficult to convince the results on EAG after silencing 63% of AspiCSP7 and AspiCSP16. dsAspiCSP7 and dsAspiCSP16 treatments reduced the electrophysiological (EAG) response to attractive (3-carene and hexanol), and repellent chemicals [nonanal and (Z)-3-hexenol], which demonstrated the behavioral results. Molecular docking indicated that critical hydrophobic residues, LYS-95 and ILE-59, might be involved in the binding of AspiCSP7 and AspiCSP16 to six host VOCs, respectively.

Conclusions

AspiCSP7 and AspiCSP16 are involved in the recognition of host VOCs, including four attractants [(E)-2-hexenal, linalool, 3-carene, hexanol] and two repellents [nonanal and (Z)-3-hexenol]. This study will deepen the understanding of the olfactory mechanisms of host VOCs recognition by A. spiniferus and will support the development of novel compounds and RNA pesticides for controlling pests.

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Exploring indoleacetic acid (IAA) biosynthesis pathways of plant growth promoting bacteria and their ability to synthesize IAA is crucial for understanding the promotion mechanism and for developing more efficient microbial fertilizer. In this study, 118 bacterial endophytic strains were isolated from tomato root and 68 isolates were identified as members of Bacillus and Pseudomonas genus. After screening abilities to synthesize IAA in vitro and promote plant growth for these identified Bacillus and Pseudomonas strains, 7 endophytic strains Bacillus sp. Y_21, B. paramycoides Y_29, B. albus Y_96, B. cereus Y_121, P. plecoglossicida Y_157, Bacillus sp. Y_165 and B. aryabhattai Y_170 strains showed a significant promotion role on wheat root or leaf, including 4 endophytic strains with the potential ability to utilize intermediate metabolites, such as tryptamine and indole acetamide, to produce IAA. Genomic sequencing analysis for selected representative plant growth promoting endophytes showed that IAA-producing bacteria B. cereus mr31 and P. putida Y_166 separately harbored a complete indoleacetamide (IAM) and complete tryptamine (TAM) pathway; whereas, Bacillus sp. Y_165 and B. aryabhattai Y_170, two strains producing IAA not using tryptophan but with indole-3-acetamide, had an incomplete IAM pathway. Fermentation experiments of three genome-sequenced strains using wheat or tomato root extracts as substrate, and combining with UHPLC–MS/MS analysis for wheat root extracts, demonstrated that Bacillus sp. Y_165 strain might produce IAA by using the plant-derived indole-3-acetamide. Our study first demonstrated a novel potential mechanism for the plant growth promoting endophytes to biosynthesize IAA using plant-derived intermediates. This additional mechanism has deepened our understanding of how bacterial endophytes promote plant health and resilience, offering valuable insights about how plants regulate IAA homeostasis within their internal tissues in association with bacterial endophytes.

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Background

Silage emits climate- and environment-relevant gases during anaerobic fermentation and aerobic feed-out periods. This trial should determine the unknown CO₂, methane, nitrous oxide, ethanol and ethyl acetate emissions of constant maize silage over both periods. The results will be published in two consecutive articles (Part A: anaerobic fermentation period; Part B: aerobic storage period).

Methods

Three silage treatments were observed (n = 4): The untreated control (CON) was compared to the chemical additive treatment (CHE; 0.5 g sodium benzoate and 0.3 g potassium sorbate per kg fresh matter) and the biological additive treatment (BIO; 1 × 10⁸ colony-forming units Lentilactobacillus buchneri and 1 × 10⁷ colony-forming units Lactiplantibacillus plantarum per kg fresh matter). During the two aerobic emission measurement periods (AEMP), the silos were ventilated mechanically to supply 2–6 (L air) min^–1 to the two faces of the material (150.6 kg dry matter m^–3). AEMP1 (duration 14 days) began on ensiling day 30, AEMP2 (19 days) on day 135.

Results

In AEMP1, aerobic stability differed among the treatments (p < 0.05): 5.17 ± 0.75 days for CON, 6.33 ± 0.15 days for BIO, and 7.33 ± 0.57 days for CHE. In AEMP2, only CON showed a temperature increase of 2 K above ambient temperature after 7.75 ± 0.31 days. BIO and CHE indicated higher ethanol and ethyl acetate emission rates during the first period of the heating process. Furthermore, 20.0%–70.4% of ethanol and 169.0%–953.6% of ethyl acetate quantities present in the material at the silo opening emitted as gases.

Conclusion

Methane and nitrous oxide emissions during anaerobic fermentation exceeded the quantities during aerobic storage in all treatments. However, compared with those of crop production, the total climate-relevant CO₂eq emissions are small. Microbial respiration during heating leads to climate-neutral CO₂ emissions and dry matter losses. Minimising these losses is promising for mitigating climate-relevant emissions directly during silage storage and indirectly during crop production since less forage input is needed. Thus, silage additives can help improve the silage carbon footprint by improving aerobic stability and silage deterioration.

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Ammonia-oxidizing microorganisms (AOM) are vital for soil nitrogen cycling, nutrient availability, and soil health during sustainable agriculture. Long-term continuous cultivation of bananas and improper chemical fertilization affect the adaptability of AOM; however, the underlying basis for this phenomenon is unclear. This study utilized 16S rRNA gene and metagenomic sequencing techniques to examine soil from banana plantations that were continuously cultivated for 2, 3, 7, 10, 12, and 13 years (Y2, Y3, Y7, Y10, Y12, and Y13, respectively). The results indicated a significant decrease in soil acidity buffering capacity (pHBC) with increasing years of continuous cropping. Furthermore, compared with forest soil (Y0), Y7, Y10, Y12, and Y13 soils exhibited a significantly increased potential nitrification rate (PNR) as well as an abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB), with no significant difference in complete ammonia oxidizers (comammox). Principal component analysis (PCA) further demonstrated marked differences in chemical properties and ammonia-oxidizing microbial community structures between the soils under long-term (Y7, Y10, Y12, Y13) and short-term (Y2, Y3) banana cultivation. In addition, metagenome analysis results indicated that the relative abundance of Nitrososphaera-AOA and Ca. Nitrosocosmicus-AOA as well as Nitrosospira-AOB, Nitrosovibrio-AOB, Nitrosomonas-AOB, and comammox Nitrospira jacus was significantly higher in Y7 and Y13 soils than in Y0 controls. Redundancy analysis (RDA) identified pHBC, CEC, and NH₄⁺ as the primary chemical factor responsible for the differences in AOM microbial communities, whereas random forest analysis revealed that Nitrosospira-AOB significantly contributed to PNR. In summary, long-term continuous banana cultivation primarily stimulates AOB promote soil ammonia oxidation, leading to soil acidification.

Graphical Abstract

Background

Among 2,3-butanediol (2,3-BDO) stereoisomers, (R,R)-2,3-BDO is particularly noteworthy for its application in the agricultural industry. It is an eco-friendly plant immune system stimulant, promoting plant growth and enhancing resistance to biotic and abiotic stresses.

Results

This study aimed to address the limitations of a previous study, which produced (R,R)-2,3-BDO with only 98% purity despite Kp-dhaD overexpression. First, BLi-gldA demonstrated significantly higher activity and selectivity in converting racemic acetoin to (R,R)-2,3-BDO compared to others among 2,3-BDO dehydrogenases (Kp-dhaD and Kp-gldA from Klebsiella pneumoniae, and BLi-gldA from Bacillus licheniformis). The K. pneumoniae GEM167 ΔadhEΔldhAΔbudC-BLi-gldA/pETM6 strain produced the highest (R,R)-2,3-BDO amount, with 99% purity (73.51 ± 1.69 g/L at 48 h), by isopropyl β-D-1-thiogalactopyranoside addition at the early exponential growth phase (6 h) compared to other cell growth phases. The availability of crude glycerol was investigated, and crude glycerol promoted cell growth resulting in efficient (R,R)-2,3-BDO in the early stage of culture [90.32 ± 1.12 g/L (R,R)-2,3-BDO with 99.0% purity after 60 h]. The productivity and yield remained comparable for crude glycerol (1.51 g/L/h, 0.41 g/g) and pure glycerol (1.53 g/L/h, 0.43 g/g).

Conclusions

This study successfully produced 99% enantiopure (R,R)-2,3-BDO from crude glycerol for the first time using the K. pneumoniae GEM167 ΔadhEΔldhAΔbudC-BLi-gldA/pETM6 strain. (R,R)-2,3-BDO production from crude glycerol, a biodiesel process byproduct, is expected to contribute to a sustainable and circular biomass supply chain and biodiesel production system by positively influencing the stable cultivation of biodiesel crops even under unpredictable climate conditions.

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