摘要：
Root-knot nematodes (Meloidogyne spp.) are highly destructive pests that cause enormous crop losses worldwide. With the increasing awareness of environmental protection, exploring the potential of biocontrol agents has become crucial for nematode management. Priestia megaterium YB-3 was originally isolated from rice rhizosphere soil. In vitro experiments with the fermentation supernatant of YB-3 exhibited up to 96.0% mortality of M. graminicola second-stage juveniles (J2) and 39.2% egg hatching inhibition rate at 48 h after treatment. In greenhouse and field experiments, the application of YB-3 significantly suppressed the gall index, final nematode and egg populations compared to the untreated control, while it promoted rice (Oryza sativa) growth. YB-3 showed consistently high biocontrol efficacy against M. graminicola. Moreover, YB-3 remarkably enhanced the expression of defence genes involved in salicylic acid (OsNPR1, OsWRKY45, OsPR1a), jasmonic acid (OsJaMYB, OsAOS2) and ethylene (OsACS1) signalling pathways at different levels. In addition, YB-3 steadily colonized rice rhizosphere soil at levels ranging from 3.54 x 103 to 9.08 x 104 cfu/g soil. High-throughput sequencing analysis showed that the application of YB-3 had no significant influence on the rice rhizosphere microbial community structure, and the taxa enriched in the YB-3 treatment were Acidobacteria, Bacteroidetes and Ascomycota. YB-3 effectively suppressed M. graminicola infection, possibly because it colonized the rice rhizosphere, induced plant resistance and increased the relative abundances of beneficial microorganisms. Priestia megaterium YB-3 could be a promising and safe biological component in the integrated management of M. graminicola.
关键词：
Tobacco mosaic virus;alpha diversity;bacterial interaction;beneficial bacteria;sensitivity of bacterial community
摘要：
BACKGROUND: Tobacco mosaic virus (TMV) is one famous plant virus responsible for substantial economic losses worldwide. However, the roles of bacterial communities in response to TMV in the tobacco rhizosphere remain unclear. METHODS: We explored the soil physicochemical properties and bacterial community succession of the healthy (YTH) and diseased (YTD) plants with TMV infection by 16S rRNA gene sequencing and bioinformatics analysis. RESULTS: We found that soil pH in the YTD group was significantly lower than in the YTH group, and the soil available nutrients were substantially higher. The bacterial community analysis found that the diversity and structure significantly differed post-TMV disease onset. With TMV inoculated, the alpha diversity of the bacterial community in the YTD was markedly higher than that in the YTH group at the early stage. However, the alpha diversity in the YTD group subsequently decreased to lower than in the YTH group. The early bacterial structure of healthy plants exhibited higher susceptibility to TMV infection, whereas, in the subsequent stages, there was an enrichment of beneficial bacterial (e.g., Ramlibacter, Sphingomonas, Streptomyces, and Niastella) and enhanced energy metabolism and nucleotide metabolism in bacteria. CONCLUSION: The initial soil bacterial community exhibited susceptibility to TMV infection, which might contribute to strengthening resistance of Tobacco to TMV.
摘要：
Micromelalopha sieversi (Staudinger, 1892) is a significant pest of Poplar trees in China. In this study, we used high-throughput sequencing to sequence the whole mitochondrial genome of M. sieversi. The length of the genome was 15,373 base pairs. The nucleotide composition was 39.8%, 11.5%, 8.0%, and 40.7% for A, C, G, and T, respectively. We used the maximum-likelihood method to construct a molecular phylogenetic tree based on complete mitogenome sequences of 19 Noctuoidea species as ingroups and five Geometroidea species as outgroups. The results indicate that the genus Micromelalopha is closely related to the genus Clostera in family Notodontidae.
摘要：
The fall armyworm, known as Spodoptera frugiperda, is a notorious invasive pest wreaking havoc on agricultural crops globally. In the course of this study, a novel variant of the S. litura multiple nucleopolyhedrovirus (SpltMNPV-T0) was isolated from S. litura larvae found on tobacco plants in China. This research delved into the molecular and biological characteristics of SpltMNPV-T0. Electron microscopy revealed that this variant exhibited the characteristics features of a baculovirus. The complete genome of SpltMNPV-T0 was 137,925 bp in length, with a G + C content of 42.88 %, housing a total of 130 open reading frames (ORFs). Phylogenetically, this variant was similar to the published genome of the SpltMNPV-G2 strain, aligning itself with the Alphabaculovirus group II. However, it distinguished itself from the SpltMNPV-II in terms of sequence similarity (76.45 %), shared ORFs (only 63 genes in common), and gene order (exhibiting inversion and reordering). Crucially, SpltMNPV-T0 demonstrated notable effectiveness in controlling third-instar larvae of S. frugiperda and S. litura. Furthermore, the virulence of crude SpltMNPV-T0 matched that of the commercially available virus-based pesticide (SpltMNPV-KY), as evident in terms of mortality rates and speed of kill. These findings yield valu able insights into the molecular biology and functional genomics of this newly discovered variant, characterized by its high virulence. Such knowledge holds promise for advancing bio-control technologies aimed at mitigating the destructive impact of the pest S. frugiperda.
作者：
Min Deng;Min Wang;Chao Tang;Bo Cai;Guang-Chang Ma;...
期刊：
Journal of Asia-Pacific Biodiversity,2024年17(1):117-124 ISSN：2287-884X
通讯作者：
Guo-Hua Huang
作者机构：
[Xing Wang] Tropical Biodiversity and Bioresource Utilization Laboratory, Qiongtai Normal University, Haikou 410128, Hunan, China;[Guo-Hua Huang] Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, College of Plant Protection, Hunan Agricultural University, Changsha 410128, Hunan, China;Qiannan Polytechnic for Nationalities, Duyun, Guizhou, China;[Min Wang] College of Plant Protection, South China Agricultural University, Guangzhou 510642, Guangdong, China;[Chao Tang; Guang-Chang Ma] Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, Hainan, China
通讯机构：
[Guo-Hua Huang] H;Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests, College of Plant Protection, Hunan Agricultural University, Changsha 410128, Hunan, China
摘要：
A new species, Cephonodes sanshaensis Deng & Huang, sp. nov. is described from Xisha islands near Sansha City, China. Photographs of the adults and their genitalia are provided. The new species is similar to C. hylas (Linnaeus, 1771) and C. picus (Cramer, 1777) but can be easily distinguished by characters in the male genitalia: the right lobe of the uncus is hook-shaped with distinctly acute apex, the left valva is long and narrow with a truncate apex, and the right valva is broad and knife-shaped. Molecular analysis based on cytochrome c oxidase I gene barcode sequences is used to infer the phylogenetic position of the new species within the genus Cephonodes. An updated key and checklist to the worldwide species of the genus Cephonodes are also provided.
摘要：
Cytochrome P450s play critical roles in the metabolic resistance of insecticides in insects. Previous findings showed that enhanced P450 activity was an important mechanism mediating indoxacarb resistance, and multiple P450 genes were upregulated in indoxacarb resistant strains of Spodoptera litura. However, the functions of these P450 genes in insecticide resistance remain unknown. Here, the P450 inhibitor PBO effectively decreased the resistance of S. litura to indoxacarb. Ten upregulated P450 genes were characterized, all of which were overexpressed in response to indoxacarb induction. Knockdown of nine P450 genes decreased cell viability against indoxacarb, and further silencing of three genes (CYP339A1, CYP340G2, CYP321A19) in larvae enhanced the sensitivity to indoxacarb. Transgenic overexpression of these three genes increased resistance to indoxacarb in Drosophila melanogaster. Moreover, molecular modeling and docking predicted that these three P450 proteins could bind tightly to indoxacarb and N-decarbomethoxylated metabolite (DCJW). Interestingly, these three P450 genes may also mediate cross-resistance to chlorantraniliprole, λ-cyhalothrin and imidacloprid. Additionally, heterologous expression and metabolic assays confirmed that three recombinant P450s could effectively metabolize indoxacarb and DCJW. This study strongly demonstrates that multiple overexpressed mitochondrial and microsomal P450 genes were involved in insecticide resistance in S. litura.
摘要：
Root rot is an important disease of tea plants owing to its unobvious early symptoms and permanent damage (Huu et al. 2016). In 2019, 5% of tea plants displayed symptoms consistent with root rot in a tea plantation (28°09'N, 113°13'E) located in Changsha city, Hunan province of China. The symptoms of the diseased tea plants ranged from wilting leaves to entirely dead. The roots had black lesions and rot typical of this disease. Symptomatic roots were collected, washed with water and disinfected with 75% ethanol, then cut into pieces and sterilized with 0.1% mercuric chloride for 30 s, 75% ethanol for 1 min, and rinsed with sterile water five times. After drying on sterilized filter paper, root tissues were cultured on potato dextrose agar (PDA) medium at 25 oC for 7 days in the dark. Four isolates, CAGF1, CAGF2, CAGF3, and CAGF4 were purified by selecting single spores. All isolates were subjected to a pathogenicity test. A conidial suspension of each strain was collected at a concentration of 2×106 conidia/mL. For the pathogenicity test, two-year-old field grown tea plants were transplanted in plastic pots containing 240 g of the rice grain-bran mixture (inoculated with 4 mL of conidial suspension and cultured for 14 days) and 960 g of sterilized soil (Huu et al. 2016). The pots without inoculated mixture served as control group. All the pots were kept in illumination incubators at 25 (o)C and a 12L:12D photoperiod. The pathogenicity test for each strain was repeated three times with three repetitions. Only strain CAGF1 exhibited pathogenicity to tea plants. Symptoms appeared on the third day post inoculation (dpi) and gradually worsened by the 7 dpi. On the 14 dpi, most leaves had died and the roots were black and partially rotten, similar to field symptoms. The reisolated fungus from potted roots was identified as CAGF1 based on ITS region and colony morphology, while isolation was attempted, CAGF1 was not isolated from the control plants, which fulfilled Koch's postulates. On PDA, the colony center of CAGF1 was purple with white margin, while on carnation leaf agar (CLA) medium was white. On CLA medium, macroconidia have 0 to 3 septa, measured 19.1 μm to 41.2 μm × 4.2 μm to 5.4 μm (mean= 31.2 μm × 4.8 μm, n=30). The microconidia were measured as 6.7 μm to 12.8 μm × 2.4 μm to 4.9 μm (mean= 10.1 μm × 3.3 μm, n=30), with 0 to 1 septa. And the chlamydospores were measured as 6.0 to 9.7μm (mean= 7.7μm, n=30). Morphologically, strain CAGF1 was identified as Fusarium oxysporum (Leslie and Summerell 2006). Additionally, the genomic DNA of strain CAGF1 was extracted by cetyltrimethylammonium bromide (CTAB) method, the internal transcribed spacer (ITS), elongation factor 1 alpha (EF-1α) and second largest subunit of RNA polymerase II (RPB2) were amplified using the primers ITS1/ITS4 (White et al. 1990), EF-1/EF-2 (Geiser et al. 2004) and fRPB2-5F/fRPB2-7cR (Liu et al. 1999), respectively. Sequences were deposited in GenBank (ITS, OK178562.1; EF-1α, OK598121.1; RPB2, OP381476.1). BLASTn searches revealed that strain CAGF1 was 100% (ON075522.1 for ITS and JX885464.1 for RPB2) and 99.6% (JQ965440.1 for EF-1α) identical to Fusarium oxysporum species complex (FOSC). Based on phylogenetic analysis, the strain CAGF1 was identified as Fusarium cugenangense, belonging to FOSC. To our knowledge, this is the first report of F. cugenangense causing root rot of tea plants in China. The findings are important for the management of this root rot and the improvement of economic benefits of tea cultivation.
作者机构：
[Zhang, Ya; Zhou, Leyin; Zeng, Hao] College of Plant Protection, Hunan Agricultural University, Changsha 410128, China;[Wang, Chong] College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China;[Yang, Xiao] Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;[Liu, Shuangqing] College of Plant Protection, Hunan Agricultural University, Changsha 410128, China. Electronic address: liushuangqing@hunau.edu.cn
通讯机构：
[Shuangqing Liu] C;College of Plant Protection, Hunan Agricultural University, Changsha 410128, China
摘要：
Phenazine-1-carboxylic acid (PCA) is a new type of agrochemical used to prevent plant diseases, but its effects on aquatic organisms are unclear. To comprehensively assess the impacts of PCA for aquatic organisms and its associated environmental risks, this study investigated, taking zebrafish as the research object, the toxicological mechanism of PCA by means of optical microscopy, hematoxylin and eosin (HE) staining, ultrastructural observation, physiological and biochemical testing, transcriptome sequencing, metabolome analysis, fluorescence quantitative PCR and molecular simulation. The results indicated that PCA was detrimental to zebrafish embryos, larvae and adults, with LC(50) values at 96h of 3.9093mg/L, 8.5075mg/L, and 13.6388mg/L, respectively. PCA caused abnormal spontaneous movement, slowed the heart rate, delayed hatching, shortened the body length, slowed growth, and caused malformations. PCA mainly affected the brain, liver, heart, and ovaries. PCA distorted cell morphology, damaged mitochondrial membranes, disintegrated mitochondrial ridges, and dissociated nuclear membranes. PCA inhibited the enzyme activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-PX), decreased the malondialdehyde (MDA) content and disrupted antioxidant effects. The results of omics studies confirmed that PCA interfered with the transcriptional and metabolic network of zebrafish, downregulating most genes and metabolites. PCA mainly affected functions related to mitochondrial steroids, lipids, sterols, oxidoreductase activity and pathways involving cofactors, steroids, porphyrin, cytochromes, which specifically bound to targets such as panx3, agmat, and ace2. PCA was moderately toxic to zebrafish, and its usage should be strictly controlled to reduce toxic effects on aquatic organisms. The results of this study provide a new insights for ecotoxicology research.
摘要：
Cowpea (Vigna unguiculata L.) is a legume consumed as a high-quality plant protein source in many parts of the world. In August 2023, it was observed that a plant disease affected cowpea growth in Yiyang (28.34°N, 112.55°E), China. The average disease incidence was 10%, resulting in 8.5% economic losses in approximately 3,000 m(2). The symptoms initially appeared as brown lesions near the stem-soil interface and the lesions were colonized by white mycelia. As the disease progressed, the disease symptoms included constriction and brown staining at the base of the stem, covered with a small amount of white mycelia. Eventually, the entire plants withered and collapsed and many sclerotia were scattered on the ground around the diseased stem. Twenty samples (10 sclerotia and 10 diseased tissue fragments) were collected from symptomatic plants for causal agent isolation. Samples were disinfected with 70% ethanol for 30 s, 5% NaClO for 1 min, rinsed three times with sterile water, dried and placed on potato dextrose agar (PDA) plates at 28℃ in the dark. In total, 20 isolates were obtained by the hyphal tip method (Terrones et al. 2022) and showed a consistent phenotype of white cottony mycelia on PDA with an growth rate of 12.9 to 21.3 mm/day (n = 20). Sclerotia formed at five to eight days post inoculation, were initially whitish, turning beige and eventually dark brown. The diameter of mature sclerotia ranged from 0.89 to 2.13 mm (mean = 1.64±0.29 mm; n =50). For pathogen identification, ITS1/ITS4 (White et al. 1990) and EF1-983F/EF1-2218R (Rehner and Buckley 2005) primers were used to amplify the internal transcribed spacer regions (ITS) and translation elongation factor-1 alpha gene (TEF-1α), respectively. The sequences of all 20 isolates showed 99% to 100% similarity withAgroathelia rolfsii sequences from GenBank by BLAST analysis. The sequences of two representative strains, ID1 and ID4, were deposited in GenBank. The ITS sequences of ID1 (OR689482) and ID4 (OR689481) were ＞99% similar to A. rolfsii strain QJ7 (593/596 bp; MZ750983) and A. rolfsii strain Kale078 (565/568 bp; MN872304), respectively. Also, TEF-1α sequences of ID1 (OR713735) and ID4 (OR713736) were ＞99% similar to the sequences of A. rolfsii strain HS-Sr (1073/1073 bp; OL416131) and A. rolfsii strain MSB1-2 (1070/1075 bp; MN702790), respectively. Phylogenetic analysis based on ITS and TEF1-α sequences indicated that ID1 and ID4 clustered into the A. rolfsii clade.Based on morphology and sequence analyses, the isolates ID1 and ID4 were identified as A. rolfsii (anamorph Sclerotium rolfsii).Pathogenicity tests were conducted three times on healthy 30-day-old cowpea seedlings. Five plants were inoculated with 6-day-old mycelial discs (6 mm) of ID1 or ID4 at the base of the seedlings (n = 30) while four plants were inoculated with a sterile PDA disc as a control (n = 12). All seedlings were cultivated in a greenhouse with a temperature of 26°C to 28°C and relative humidity 60% to 80% with a 14/10 h light/dark photoperiod. Eight days later, all the fungal inoculated seedlings showed symptoms including brown necrosis and collapse of the stems, and eventual withering of the seedlings. Control plants remained asymptomatic. The causal pathogens were reisolated in PDA plates and identified by ITS sequence analysis, completing Koch's postulates. To our knowledge, this is the first report ofA. rolfsiicausing southern blight oncowpea in China. Early accurate diagnosis will help farmers to adopt suitable practices to control disease outbreaks and reduce losses.
摘要：
The phenylalanine ammonia-lyase (PAL) enzyme catalyses the conversion of l-phenylalanine to trans-cinnamic acid. This conversion is the first step in phenylpropanoid biosynthesis in plants. The phenylpropanoid pathway produces diverse plant metabolites that play essential roles in various processes, including structural support and defence. Previous studies have shown that mutation of the PAL genes enhances disease susceptibility. Here, we investigated the functions of the rice PAL genes using 2-aminoindan-2-phosphonic acid (AIP), a strong competitive inhibitor of PAL enzymes. We show that the application of AIP can significantly reduce the PAL activity of rice crude protein extracts in vitro. However, when AIP was applied to intact rice plants, it reduced infection of the root-knot nematode Meloidogyne graminicola. RNA-seq showed that AIP treatment resulted in a rapid but transient upregulation of defence-related genes in roots. Moreover, targeted metabolomics demonstrated higher levels of jasmonates and antimicrobial flavonoids and diterpenoids accumulating after AIP treatment. Furthermore, chemical inhibition of the jasmonate pathway abolished the effect of AIP on nematode infection. Our results show that disturbance of the phenylpropanoid pathway by the PAL inhibitor AIP induces defence in rice against M. graminicola by activating jasmonate-mediated defence.
摘要：
Tobacco (Nicotiana tabacum L.) is an important economic crop that is widely grown around the world. Its annual production in China is estimated at 2.2 million tons (Berbeć and Matyka 2020). Since 2022, a root rot disease was sporadically observed on tobacco seedlings on cultivar Yunyan 87 in cultivated tobacco fields in the Hunan province of China. A disease incidence of about 10% occurred across 48 ha of tobacco fields. The affected tobacco plants had slow and stunted growth with yellowing leaves. The roots turned grayish brown, decayed, and died. Diseased roots were collected from six fields and cut into small pieces (5 mm ×5 mm) from the edge of the rotted portions, and then sterilized with 70% ethanol for 10 s, 0.1% HgCl2 for 1 min, and washed in sterilized water three times. All the sterilized tissue were placed on potato dextrose agar (PDA) medium and cultured at 26 ℃ in the dark. About 3 days later, colonies with similar morphology were removed and sub-cultured on fresh PDA. A total of six strains were obtained from six tobacco samples. Strains were white and had radial growth on PDA. Hyphae were aseptate and the sporangia were filamentous. The oogonia were subglobose, smooth, 16.04 ± 0.25 µm (n=50) in diameter, and developed on unbranched stalks. The antheridia were barrel shaped and clavate. Oospores were globose, aplerotic or nearly plerotic, measuring 6.62 ± 0.33 µm (n=50). These morphological characteristics were consistent with the description of Pythium spp. (van der Plaats-Niterink 1981). For molecular identification, the internal transcribed spacer (ITS) region of rDNA and cytochrome c oxidase subunit I (Cox I) of a representative isolate, GF-3, were amplified and sequenced (GenBank accession nos. OR228424 for ITS and OR237556 for Cox I) using universal primers ITS1/ITS4 (White et al. 1990) and FM58/FM66, respectively (Villa et al. 2006). BLASTn analysis revealed that the ITS and Cox I sequences were 99.76 % (838/840 bp) and 99.85% (671/672 bp) identical to the corresponding sequences of P. dissotocum strain CBS 166.68 (AY598634.2) and UM982 (MT981147.1), respectively. A neighbor-joining phylogenetic tree based on the Cox I sequence showed that GF-3 grouped in the P. dissotocum branch. Based on morphological and molecular characteristics, GF-3 was identified to be P. dissotocum. For pathogenicity testing, four- to five-leaf-old healthy potted tobacco seedlings of the Yunyan 87 cultivar were inoculated with a zoospore suspension (1 × 105 zoospores/ml), which was induced on V8-juice medium. The zoospore suspension was introduced into the soil around plant roots and 10 mL of inoculum was used for each plant. In the control group, plants were inoculated with sterilized water. All of the treated plants were kept in humid chambers at 26°C under a 12 h/12 h photoperiod. The pathogenicity assays were performed twice, with each treatment having three replicated plants. After 5 days, tobacco seedlings inoculated with P. dissotocum showed symptoms resembling that observed in the field. However, the control plants remained healthy. Pythium dissotocum was re-isolated from the infected plants and identified by morphological and molecular methods, thus confirming Koch's postulates. Pythium dissotocum has been reported causing root rot in other plants, including hydroponic lettuce (McGehee et al. 2018) and spinach (Huo et al. 2020). Also, many Pythium species have recently been recovered from float-bed tobacco transplant production greenhouses (Zhang et al. 2022). However, to our knowledge, this is the first report of root rot on tobacco caused by P. dissotocum in China. Since this disease could greatly affect tobacco seedling establishment in the field, appropriate management strategies need to be developed to reduce further losses in tobacco planting fields.
期刊：
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY,2024年72(10):5153-5164 ISSN：0021-8561
作者机构：
[Liu, Shaonan; Ji, Yao; Zhang, Youjun; Huang, Mingjiao] College of Plant Protection, Hunan Agricultural University, Changsha 410125, P. R. China;[Liu, Shaonan; Ji, Yao; Yang, Xin; Zhang, Youjun; Xue, Hu; He, Chao; Du, He; Yin, Cheng; Liang, Jinjin; Fu, Buli; Hu, JinYu; Wang, Chao; Wei, Xuegao; Du, Tianhua; Yang, Jing; Huang, Mingjiao; Gong, Peipan; Zhang, Rong] State Key Laboratory of Vegetable Biobreeding, Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China;[Fu, Buli] The Ministry of Agriculture and Rural Affairs Key Laboratory of Integrated Pest Management of Tropical Crops, Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou 571101, P. R. China;[Xue, Hu; Yin, Cheng; Hu, JinYu; Wang, Chao; Wei, Xuegao; Zhang, Rong] Hubei Engineering Technology Center for Pest Forewarning and Management, College of Agriculture, Yangtze University, Jingzhou, Hubei 434025, P. R. China
摘要：
Being a destructive pest worldwide, the whitefly Bemisia tabaci has evolved resistance to neonicotinoid insecticides. The third-generation neonicotinoid dinotefuran has commonly been applied to the control of the whitefly, but its underlying mechanism is currently unknown. On the base of our transcriptome data, here we aim to investigate whether the cytochrome P450 CYP6EM1 underlies dinotefuran resistance in the whitefly. Compared to the susceptible strain, the CYP6EM1 gene was found to be highly expressed in both laboratory and field dinotefuran-resistant populations. Upon exposure to dinotefuran, the mRNA levels of CYP6EM1 were increased. These results demonstrate the involvement of this gene in dinotefuran resistance. Loss and gain of functional studies in vivo were conducted through RNAi and transgenic Drosophila melanogaster assays, confirming the role of CYP6EM1 in conferring such resistance. In a metabolism assay in vitro, the CYP6EM1 protein could metabolize 28.11% of dinotefuran with a possible dinotefuran-dm-NNO metabolite via UPLC-QTOF/MS. Docking of dinotefuran to the CYP6EM1 protein showed a good binding affinity, with an energy of less than -6.0 kcal/mol. Overall, these results provide compelling evidence that CYP6EM1 plays a crucial role in the metabolic resistance of B. tabaci to dinotefuran. Our work provides new insights into the mechanism underlying neonicotinoid resistance and applied knowledge that can contribute to sustainable control of a global pest such as whitefly.
摘要：
Mesoporous silica nanoparticles (MSNs) can be used as carrier materials for the controlled release of pesticides while reducing their negative environmental impact. In this study, we screened an active ingredient, p-cymene (PC), with an excellent inhibitory effect on rice bacterial blight. Subsequently, the PC was successfully loaded onto MSNs via physisorption (PC@MSNs). PC@MSNs, characterized by a regular spherical shape, smooth surface, and an MSN average size of 262.9 nm, achieved an 8.6% drug loading capacity. The release kinetics of the PC from the PC@MSNs demonstrated a sustained release (288 h) pattern influenced by drug diffusion. The efficacy of the PC@MSNs against Xanthomonas oryzae pv. Oryzae paralleled those of PC. Acute toxicity assays revealed that the PC@MSNs were less toxic to aquatic life (LC(50) = 257.867 mg/L) and that the formulation showed no adverse effects on rice seedling growth. In summary, these results suggest that PC@MSNs can broaden PC's scope of application in managing rice diseases.
摘要：
Pre-parasitic second-stage juveniles (pre-J2s) of Meloidogyne graminicola are non-feeding in soil, and their migration, localization and successful invasion of host roots are essential for survival. Chemotaxis is thought to play a central role in host localization, but the mechanisms of chemotaxis are poorly understood. In this study, we cloned and evaluated the molecular characteristics and functions of four chemosensory genes, including Mg-odr-3, Mg-odr-1, Mg-tax-4, and Mg-osm-9. Quantitative real-time PCR (qRT-PCR) analysis revealed that Mg-odr-3 and Mg-osm-9 tended to be expressed in pre-J2s and parasitic J2s (par-J2s), while Mg-odr-1 and Mg-tax-4 were expressed in par-J2s, consistent with their functions during the host-seeking period and establishment of suitable feeding sites in root tips. Root signals from eight plant root extracts, namely, rice, barnyard grass (Echinochloa crus-galli), wheat, soybean, pepper, tomato, eggplant, and marigold, were repulsive to J2s of M. graminicola. Moreover, RNAi silencing of Mg-odr-3, Mg-odr-1, Mg-tax-4, and Mg-osm-9 in J2s attenuated their repulsion to the rice root extract. Furthermore, we found that the response of J2s to root exudates was concentration-dependent, with high concentrations of root exudates repelling J2s. Silenced J2s also showed reduced repulsion in response to high concentrations of rice root exudates. Conversely, M. graminicola J2s were attracted to the root tips of the eight plants, while RNAi-J2s showed defective attraction to root tips. In conclusion, our results showed that chemosensory genes are crucial for the chemotactic host-seeking behaviour of M. graminicola.
摘要：
Previous research has shown that the pathogenicity and appressorium development of Magnaporthe oryzae can be inhibited by the ATP synthase subunit beta (Atp2) present in the photosynthetic bacterium Rhodopseudomonas palustris. In the present study, transgenic plants overexpressing the ATP2 gene were generated via genetic transformation in the Zhonghua11 (ZH11) genetic background. We compared the blast resistance and immune response of ATP2-overexpressing lines and wild-type plants. The expression of the Atp2 protein and the physiology, biochemistry, and growth traits of the mutant plants were also examined. The results showed that, compared with the wild-type plant ZH11, transgenic rice plants heterologously expressing ATP2 had no significant defects in agronomic traits, but the disease lesions caused by the rice blast fungus were significantly reduced. When infected by the rice blast fungus, the transgenic rice plants exhibited stronger antioxidant enzyme activity and a greater ratio of chlorophyll a to chlorophyll b. Furthermore, the immune response was triggered stronger in transgenic rice, especially the increase in reactive oxygen species (ROS), was more strongly triggered in plants. In summary, the expression of ATP2 as an antifungal protein in rice could improve the ability of rice to resist rice blast.
摘要：
The rice stem borer (RSB, Chilo suppressalis) is a significant agricultural pest that mainly depends on chemical control. However, it has grown to varied degrees of pesticide resistance, which poses a severe threat to rice production and emphasizes the need for safer, more efficient alternative pest management strategies. Here, in vitro and in vivo experiments analyses reveal miR-1579 binds to the critical transcription factor Kruppel ho-mologue 1 (Kr-h1) and negatively regulates its expression. Overexpression of miR-1579 in larvae with signifi-cantly lower levels of Kr-h1 was associated with a decline in larval growth and survival. Furthermore, in female pupae, miR-1579 overexpression led to abnormalities in ovarian development, suggesting that targeting miR-1579 could be a potential management strategy against C. suppressalis. Therefore, we generated transgenic rice expressing miR-1579 and screened three lines that had a single copy of highly abundant mature miR-1579 transcripts. Expectedly, fed with transgenic miR-1579 rice lines were significantly lower survival rates in larvae and high levels of resistance to damage caused by C. suppressalis infestation. These findings suggest that miRNA-mediated RNAi could provide an effective and species-specific strategy for C. suppressalis control.
摘要：
The root-knot nematode Meloidogyne graminicola secretes effectors into rice tissues to modulate host immunity. Here, we characterised MgCRT1, a calreticulin protein of M. graminicola, and identified its target in the plant. In situ hybridisation showed MgCRT1 mRNA accumulating in the subventral oesophageal gland in J2 nematodes. Immunolocalization indicated MgCRT1 localises in the giant cells during parasitism. Host-induced gene silencing of MgCRT1 reduced the infection ability of M. graminicola, while over-expressing MgCRT1 enhanced rice susceptibility to M. graminicola. A yeast two-hybrid approach identified the calmodulin-like protein OsCML31 as an interactor of MgCRT1. OsCML31 interacts with the high mobility group protein OsHMGB1 which is a conserved DNA binding protein. Knockout of OsCML31 or overexpression of OsHMGB1 in rice results in enhanced susceptibility to M. graminicola. In contrast, overexpression of OsCML31 or knockout of OsHMGB1 in rice decreases susceptibility to M. graminicola. The GST-pulldown and luciferase complementation imaging assay showed that MgCRT1 decreases the interaction of OsCML31 and OsHMGB1 in a competitive manner. In conclusion, when M. graminicola infects rice and secretes MgCRT1 into rice, MgCRT1 interacts with OsCML31 and decreases the association of OsCML31 with OsHMGB1, resulting in the release of OsHMGB1 to enhance rice susceptibility.
摘要：
The contamination of the plant phyllosphere with antibiotics and antibiotic resistance genes (ARGs), caused by application of antibiotics, is a significant environmental issue in agricultural management. Alternatively, biocontrol agents are environmentally friendly and have attracted a lot of interest. However, the influence of biocontrol agents on the phyllosphere resistome remains unknown. In this study, we applied biocontrol agents to control the wildfire disease in the Solanaceae crops and investigated their effects on the resistome and the pathogen in the phyllosphere by using metagenomics. A total of 250 ARGs were detected from 15 samples, which showed a variation in distribution across treatments of biocontrol agents (BA), BA with Mg(2+) (T1), BA with Mn(2+) (T2), and kasugamycin (T3) and nontreated (CK). The results showed that the abundance of ARGs under the treatment of BA-Mg(2+) was lower than that in the CK group. The abundance of cphA3 (carbapenem resistance), PME-1 (carbapenem resistance), tcr3 (tetracycline antibiotic resistance), and AAC (3)-VIIIa (aminoglycoside antibiotic resistance) in BA-Mg(2+) was significantly higher than that in BA-Mn(2+) (P < 0.05). The abundance of cphA3, PME_1, and tcr3 was significantly negatively related to the abundance of the phyllosphere pathogen Pseudomonas syringae (P < 0.05). We also found that the upstream and downstream regions of cphA3 were relatively conserved, in which rpl, rpm, and rps gene families were identified in most sequences (92%). The Ka/Ks of cphA3 was 0 in all observed sequences, indicating that under the action of purifying selection, nonsynonymous substitutions are often gradually eliminated in the population. Overall, this study clarifies the effect of biocontrol agents with Mg(2+) on the distribution of the phyllosphere resistome and provides evolutionary insights into the biocontrol process. IMPORTANCE: Our study applied metagenomics analysis to examine the impact of biocontrol agents (BAs) on the phyllosphere resistome and the pathogen. Irregular use of antibiotics has led to the escalating dissemination of antibiotic resistance genes (ARGs) in the environment. The majority of BA research has focused on the effect of monospecies on the plant disease control process, the role of the compound BA with nutrition elements in the phyllosphere disease, and the resistome is still unknown. We believe BAs are eco-friendly alternatives for antibiotics to combat the transfer of ARGs. Our results revealed that BA-Mg(2+) had a lower relative abundance of ARGs compared to the CK group, and the phyllosphere pathogen Pseudomonas syringae was negatively related to three specific ARGs, cphA3, PME-1, and tcr3. These three genes also present different Ka/Ks. We believe that the identification of the distribution and evolution modes of ARGs further elucidates the ecological role and facilitates the development of BAs, which will attract general interest in this field.
摘要：
This study presents the development of thermoresponsive pyraclostrobin (PYR) microcapsules (PYR@PNIPAm-MCs) designed for controlled temperature-regulated pesticide release. These microcapsules, characterized by a regular spherical shape, smooth surface, and average size of 7.08 mu m, achieved a 14.99% drug loading capacity. Wide-angle X-ray diffraction (WAXD) analysis confirmed the efficient encapsulation of PYR. The release kinetics of PYR from the PYR@PNIPAm-MCs demonstrated a sustained, temperature-sensitive release pattern influenced by drug diffusion and matrix erosion. The efficacy of the PYR@PNIPAm-MCs against Magnaporthe oryzae paralleled that of 97% PYR technical concentrate at elevated temperatures. Acute toxicity assays revealed a significantly reduced toxicity of PYR@PNIPAm-MCs to aquatic life (LC50 = 7.71 mg/L), and the formulation showed no adverse effects on rice seedling growth. The results underscore the potential of this formulation to enhance the application of PYR in rice disease management, offering targeted release and improved safety profiles.
