Pine wood nematode disease is a most devastating disease of pine trees. Avermectin (AVM) is a widely used bio-nematocide which can effectively to kill the pine wood nematode (PWN). However, its poor ...solubility in water and rapid photolysis are responsible for its poor bioavailability, which causes environmental pollution because of excessive applied rates. Here, a simple electrostatic interaction method was used to encapsulate AVM within nanoparticles composed of poly-γ-glutamic acid (γ-PGA) and chitosan (CS). The loading capacity of the resulting AVM-CS/γ-PGA nanoparticles was as much as 30.5%. The encapsulation of AVM within these nanoparticles reduced its losses by more than 20.0% through photolysis. An in vitro test showed that the rate of release of AVM from the nanoparticles was dependent on the ambient pH, with rapid release occurring in an alkaline environment. The mortality rate of nematodes which were treated with 1ppm of AVM content of AVM-CS/γ-PGA was 98.6% after 24h, while one of free AVM was only 69.9%. In addition, FITC-labeled CS/γ-PGA nanoparticles (FITC-CS/γ-PGA) showed that the nanoparticles could enrich in intestines and head of nematodes. All of these results showed that those nanoparticles of AVM are a potential multifunctional formulation to control the pest and reduce environment pollution.
Chitosan-based nanoparticles were synthesized as an improving water dispersibility, anti-photolysis, high nematicidal activity under the water and controlled-release multifunctional nanocarrier of pesticides. Display omitted
Design and discovery of carrier-mediated modified pesticides are vital for reducing pesticide dosage and increasing utilization, yet it remains a great challenge due to limited insights into plant ...translocation mechanisms. Nanostructure/nanoparticle assisted laser desorption/ionization strategy has established itself as a preferential analytical tool for biological tissue analysis, whereas potential applications in plant sciences are hindered with regard to the inability to slice plant leaves and petals. Herein, we report gold nanoparticle (AuNP)-immersed paper imprinting mass spectrometry imaging (MSI) for the spatiotemporal visualization of pesticide translocation in plant leaves. This approach plays a dual role in preserving spatial information and improving ionization efficiency for pesticides regardless of imaging artifacts due to homogenous AuNP deposition. Using this MSI platform, we proposed the elaborate plant translocation mechanism of agrochemicals for the first time, which is currently poorly understood. The dynamic processes of carrier-mediated pesticides can be clearly visualized, including crossing of plasma membranes by transporters, translocation downward in stems through the phloem, diffusion to the xylem and, conversely, accumulation at margins of the treated leaves. Moreover, this AuNP-assisted paper imprinting method could be highly compatible with laser-based MSI instruments, expediting researches across a broad range of fields, especially in nanomaterial development and life sciences.
Summary
Characterization and genetic engineering of plant transporters involved in the pesticide uptake and translocation facilitate pesticide relocation to the tissue where the pests feed, thus ...improving the bioavailability of the agrichemicals. We aimed to identify thiamethoxam (THX) transporters in rice and modify their expression for better brown planthopper (BPH) control with less pesticide application. A yeast library expressing 1385 rice transporters was screened, leading to the identification of an amino acid transporter‐like (ATL) gene, namely OsATL15, which facilitates THX uptake in both yeast cells and rice seedlings. In contrast to a decrease in THX content in osatl15 knockout mutants, ectopic expression of OsATL15 under the control of the CaMV 35S promoter or a vascular‐bundle‐specific promoter gdcsPpro significantly increased THX accumulation in rice plants, thus further enhancing the THX efficacy against BPH. OsATL15 was localized in rice cell membrane and abundant in the root transverse sections, vascular bundles of leaf blade, and stem longitudinal sections, but not in hull and brown rice at filling stages. Our study shows that OsATL15 plays an essential role in THX uptake and its systemic distribution in rice. OsATL15 could be valuable in achieving precise pest control by biotechnology approaches.
OsATL15 overexpression enhanced THX uptake and consequently, conferred more effective control of brown planthopper than that observed in wild‐type plants, whereas knocking out OsATL15 led to decreased accumulation of THX and increased damage by brown planthopper.
Insects rely on chemosensory perception, mainly olfaction, for the location of mates, food sources, and oviposition sites. Plant-released volatile compounds guide herbivorous insects to search for ...and locate their host plants, further helping them to identify suitable positions for oviposition. The fall armyworm Spodoptera frugiperda (S. frugiperda) was found to invade China in 2019 and has since seriously threatened multiple crops, particularly maize and rice. However, the chemical and molecular mechanisms underlying oviposition preference in this pest are not fully understood. Here, the oviposition preference of S. frugiperda on maize and rice plants was investigated.
GC-EAD and GC-MS/MS techniques were used to identify the antennally active volatiles from maize and rice plants. The attraction and oviposition stimulation of identified components to female adults were tested in both laboratory and field settings. The odorant receptors (ORs) on female antennae were expressed in Xenopus oocytes, and their functions evaluated by RNAi. Ten and eleven compounds of maize and rice plants, respectively, were identified to possess electrophysiological activity from headspace volatiles. Among these compounds, (Z)-3-hexenyl-acetate specifically presented in maize volatiles was found to play a critical role in attracting females and stimulating oviposition compared to rice volatiles. Among the cloned ORs on the antennae of both sexes, SfruOR23 with highly female-biased expression mediated the responses of females to (Z)-3-hexenyl-acetate. Knockdown of SfruOR23 using RNAi markedly reduced the electrophysiological response of female antennae and oviposition preference to the compound.
(Z)-3-Hexenyl-acetate is a key volatile mediating the host and oviposition preference of S. frugiperda on maize. The olfactory receptor of (Z)-3-hexenyl-acetate was identified to be SfruOR23, which is mainly expressed in the antennae of S. frugiperda.
Genes that participate in the degradation or isolation of glyphosate in plants are promising, for they endow crops with herbicide tolerance with a low glyphosate residue. Recently, the aldo-keto ...reductase (AKR4) gene in
(
) was identified as a naturally evolved glyphosate-metabolism enzyme. Here, we compared the glyphosate-degradation ability of theAKR4 proteins from maize, soybean and rice, which belong to a clade containing EcAKR4 in the phylogenetic tree, by incubation of glyphosate with AKR proteins both in vivo and in vitro. The results indicated that, except for OsALR1, the other proteins were characterized as glyphosate-metabolism enzymes, with ZmAKR4 ranked the highest activity, and OsAKR4-1 and OsAKR4-2 exhibiting the highest activity among the AKR4 family in rice. Moreover, OsAKR4-1 was confirmed to endow glyphosate-tolerance at the plant level. Our study provides information on the mechanism underlying the glyphosate-degradation ability of AKR proteins in crops, which enables the development of glyphosate-resistant crops with a low glyphosate residue, mediated by AKRs.
In view of the lethal toxicity of paraquat (PQ) on human health, herein, a simple indicator displacement assay (IDA) based on an azo-modified calixarene host (azoCX4) and a fluorophore guest (
-DPD) ...were elaborately constructed for PQ detection in environmental water samples and plant surfaces. The fluorescent signal of
-DPD in the probe can be quenched by azoCX4 through a photon-induced electron transfer process and recovered upon the addition of PQ within 10 s. The detection range of the
-DPD@azoCX4 probe was calculated to be 0.35-8 μM in the Tris-HCl buffer solutions (pH = 7.4). Moreover, this probe exhibited excellent detection selectivity toward PQ over five herbicides (glyphosate, bispyribac, atrazine, ametryn, and bensulfuron methyl), together with anti-interference abilities in the presence of inorganic ions (K
, Na
, Zn
, Ni
, Li
, F
, Cl
, Br
, CO
, HCO
, and NO
) and amino acids (Asp, Arg, Glu, Ala, and Cys). Particularly, the probe was successfully used to detect PQ in real water samples with acceptable accuracy and showed potential applications for on-site detection with paper-based test strips and on the leaf surface. We believe that this simplified IDA-based probe provided an effective detecting tool for PQ, and the design strategy would guide the further development of new IDA sensing systems.
As a wildly used plant-derived insecticide, azadirachtin (AZA) is commonly reported as harmless to a range of beneficial insects. However, with the research on the effect of AZA against pollinators ...in recent years, various negative physiological effects on other Apidae species have been demonstrated. Thus to explore the safety of azadirachtin to Apis cerana cerana, the different physiological effects of sublethal concentration of azadirachtin on worker bees A.c.cerana has been studied. With the exposure of 5 mg·L-1 and 10 mg·L-1 azadirachtin for 5 d, the relative expression of Apidaecin, Abaecin and Lysosome genes in workers has decreased significantly at 1, 2,3 and 5 d, and the mRNA levels of Defensin 2 and Hymenoptaecin were also significantly inhibited by 10 mg·L-1 azadirachtin at each check point. Besides, the activity of midgut antioxidant enzymes Superoxide Dismutase (SOD) and Catalase (CAT) which are the first line of defence in antioxidant systems was not affected by AZA, the activity of Peroxidase (POD) showed a fluctuating pattern at 24 h and 48 h, while the activity of polyphenol oxidase (PPO) has significantly inhibited by AZA. However, through 16sRNA analysis it was observed that 5 mg·L-1 AZA did not affect the midgut microbiome colony composition and relative abundance, as well as its main function. Therefore, to a certain extent, azadirachtin is safe for workers, but we should pay more attention to the sublethal effect of AZA that also detrimental to the healthy development of the honeybee colony.
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•Azadirachtin has down-regulated Apidaecin, Lysosome, Abaecin and Vitellogenin genes.•Azadirachtin has no effect on the activities of superoxide dismutase and catalase.•Azadirachtin did not affect the composition and function of midgut microbes.•Azadirachtin significantly inhibite the activity of polyphenol oxidase
Plant immune responses can be induced by plant growth-promoting rhizobacteria (PGPRs), but the exact compounds that induce resistance are poorly understood. Here, we identified the novel natural ...elicitor 3,4-dihydroxy-3-methyl-2-pentanone from the PGPR Bacillus subtilis HN09, which dominates HN09-induced systemic resistance (ISR).
The HN09 strain, as a rhizobacterium that promotes plant growth, can induce systemic resistance of Arabidopsis thaliana plants against Pseudomonas syringae pv. tomato DC3000, and the underlying role of its metabolite 3,4-dihydroxy-3-methyl-2-pentanone in this induced resistance mechanism was explored in this study. The stereoisomers of 3,4-dihydroxy-3-methyl-2-pentanone exhibited differential bioactivity of resistance induction in A. thaliana. B16, a 1:1 mixture of the threo-isomers (3R,4S) and (3S,4R), was significantly superior to B17, a similar mixture of the erythro-isomers (3R,4R) and (3S,4S). Moreover, B16 induced more expeditious and stronger callose deposition than B17 when challenged with the pathogen DC3000. RT-qPCR and RNA-seq results showed that B16 and B17 induced systemic resistance via JA/ET and SA signalling pathways. B16 and B17 activated different but overlapping signalling pathways, and these compounds have the same chemical structure but subtle differences in stereo configuration.
Our results indicate that 3,4-dihydroxy-3-methyl-2-pentanone is an excellent immune elicitor in plants. This compound is of great importance to the systemic resistance induced by HN09. Its threo-isomers (3R,4S) and (3S,4R) are much better than erythro-isomers (3R,4R) and (3S,4S). This process involves SA and JA/ET signalling pathways.
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