Evaluation of the control efficacy of antagonistic bacteria from V-Ti magnetite mine tailings on kiwifruit brown spots in pot and field experiments.

Seemingly barren heavy-metal-polluted vanadium (V) and titanium (Ti) magnetite mine tailings contain various functional microbes, yet it is unclear whether this includes microbial resources relevant to the biological control of plant diseases. Kiwifruit brown leaf spot disease, caused by Corynespora cassiicola, can seriously reduce kiwifruit yield. To discover effective control measures for kiwifruit leaf spot, 18 bacteria strains among 136 tailing-isolated bacteria from V-Ti magnetite mine tailings were identified as inhibiting C. cassiicola by the confrontation plate method, indicating that antagonistic bacteria surviving in the V-Ti magnetite mine tailings were present at a low level. The 18 antagonistic strains could be divided into two BOX-A1R clusters. The 13 representative strains that were selected for phylogenetic tree construction based on their 16S rRNA sequences belonged to the Bacillus genus. Five predominant strains exhibited different toxin-production times and intensities, with four of them initiating toxin production at 32 h. Among them, Bacillus sp. KT-10 displayed the highest bacteriostatic rate (100%), with a 37.5% growth inhibition rate and an antagonistic band of 3.2 cm against C. cassiicola. Bacillus sp. KT10 also showed a significant inhibitory effect against the expansion speed of kiwifruit brown spots in the pot. The relative control effect was 78.48 and 83.89% at 7 days after the first and last spraying of KT-10 dilution, respectively, confirming a good effect of KT-10 on kiwifruit brown leaf spots in the field. This study demonstrated for the first time that there are some antagonistic bacteria to pathogenic C. cassiicola in V-Ti magnetite mine tailings, and Bacillus sp. KT10 was found to have a good control effect on kiwifruit brown leaf spots in pots and fields, which provided an effective biological control measurement for kiwifruit brown leaf spots.

Molluscicidal effect mechanism study on metaldehyde to Pomacea canaliculate at low temperature.

BACKGROUND: Metaldehyde is a molluscicide commonly used to control Pomacea canaliculate. Its efficacy is significantly impacted by water temperature, although the underlying mechanisms have not been fully explored. RESULTS: In this study, we systematically investigated the temperature effect and molecular mechanisms of metaldehyde on P. canaliculata. The molluscicidal effect at various temperatures indicated that metaldehyde's molluscicidal activity significantly decreases with a drop in temperature. The LC50 value was only 458.8176 mg/L at 10 °C, while it surged to a high of 0.8249 mg/L at 25 °C. The impact of low temperature (10 °C) on metaldehyde's molluscicidal activity was analyzed via transcriptomics. The results revealed that the effect of low temperature primarily influences immunity, lipid synthesis, and oxidative stress. The expression of stress and immune-related genes, such as MANF, HSP70, Cldf7, HSP60, and PclaieFc, significantly increased. Furthermore, we studied the function of five target genes using RNA interference (RNAi) and discovered that Cldf7 and HSP70 could notably affect metaldehyde's molluscicidal effect. The mortality of P. canaliculata increased by 36.17% (72 h) after Cldf7 interference and by 48.90% (72 h) after HSP70 interference. CONCLUSION: Our findings demonstrate that low temperature can induce the extensive expression of the Cldf7 and HSP70 genes, resulting in a substantial reduction in metaldehyde's molluscicidal activity. © 2024 Society of Chemical Industry.

Molecular evolution and phylogeographic analysis of wheat dwarf virus.

Wheat dwarf virus (WDV) has caused considerable economic loss in the global production of grain crops. Knowledge of the evolutionary biology and population history of the pathogen remain poorly understood. We performed molecular evolution and worldwide phylodynamic analyses of the virus based on the genes in the protein-coding region of the entire viral genome. Our results showed that host-driven and geography-driven adaptation are major factors that affects the evolution of WDV. Bayesian phylogenetic analysis estimates that the average WDV substitution rate was 4.240 × 10-4 substitutions/site/year (95% credibility interval, 2.828 × 10-4-5.723 × 10-4), and the evolutionary rates of genes encoding proteins with virion-sense transcripts and genes encoding proteins with complementary-sense transcripts were different. The positively selected sites were detected in only two genes encoding proteins with complementary-sense, and WDV-barley are subject to stronger purifying selection than WDV-wheat. The time since the most recent common WDV ancestor was 1746 (95% credibility interval, 1517-1893) CE. Further analyses identified that the WDV-barley population and WDV-wheat population experienced dramatic expansion-decline episodes, and the expansion time of the WDV-barley population was earlier than that of the WDV-wheat population. Our phylogeographic analysis showed that the WDV population originating in Iran was subsequently introduced to Europe, and then spread from Eastern Europe to China.

Inhibition of high sulfur on functional microorganisms and genes in slightly contaminated soil by cadmium and chromium.

It is generally accepted that sulfur can passivate the bioavailability of heavy metals in soil, but it is not clear whether high sulfur in cadmium (Cd) and chromium (Cr) contaminated soil has negative effect on soil microbial community and ecological function. In this study, total sulfur (TS) inhibited the Chao 1, Shannon, Phylogenetic diversity (Pd) of bacterial and Pd of fungi in slightly contaminated soil by Cd and Cr around pyrite. TS, total potassium, pH, total chromium, total cadmium, total nitrogen, soil organic matter were the predominant factors for soil microbial community; the contribution of TS in shaping bacterial and fungal communities ranked at first and fifth, respectively. Compared with the low sulfur group, the abundance of sulfur sensitive microorganisms Gemmatimonas, Pseudolabrys, MND1, and Schizothecium were decreased by 68.79-97.22% (p < 0.01) at high sulfur one; the carbon fixation, nitrogen cycling, phosphorus cycling and resistance genes abundance were significantly lower (p < 0.01) at the latter. Such variations were strongly and closely correlated to the suppression of energy metabolism (M00009, M00011, M00086) and carbon fixation (M00173, M00376) functional module genes abundance in the high sulfur group. Collectively, high sulfur significantly suppressed the abundances of functional microorganisms and functional genes in slightly contaminated soil with Cd and Cr, possibly through inhibition of energy metabolism and carbon fixation of functional microorganisms. This study provided new insights into the environmental behavior of sulfur in slightly contaminated soil with Cd and Cr.

Magnaporthe oryzae effector MoSPAB1 directly activates rice Bsr-d1 expression to facilitate pathogenesis.

Fungal pathogens typically use secreted effector proteins to suppress host immune activators to facilitate invasion. However, there is rarely evidence supporting the idea that fungal secretory proteins contribute to pathogenesis by transactivating host genes that suppress defense. We previously found that pathogen Magnaporthe oryzae induces rice Bsr-d1 to facilitate infection and hypothesized that a fungal effector mediates this induction. Here, we report that MoSPAB1 secreted by M. oryzae directly binds to the Bsr-d1 promoter to induce its expression, facilitating pathogenesis. Amino acids 103-123 of MoSPAB1 are required for its binding to the Bsr-d1 promoter. Both MoSPAB1 and rice MYBS1 compete for binding to the Bsr-d1 promoter to regulate Bsr-d1 expression. Furthermore, MoSPAB1 homologues are highly conserved among fungi. In particular, Colletotrichum fructicola CfSPAB1 and Colletotrichum sublineola CsSPAB1 activate kiwifruit AcBsr-d1 and sorghum SbBsr-d1 respectively, to facilitate pathogenesis. Taken together, our findings reveal a conserved module that may be widely utilized by fungi to enhance pathogenesis.

Real-Time Detection Algorithm for Kiwifruit Canker Based on a Lightweight and Efficient Generative Adversarial Network.

Disease diagnosis and control play important roles in agriculture and crop protection. Traditional methods of identifying plant disease rely primarily on human vision and manual inspection, which are subjective, have low accuracy, and make it difficult to estimate the situation in real time. At present, an intelligent detection technology based on computer vision is becoming an increasingly important tool used to monitor and control crop disease. However, the use of this technology often requires the collection of a substantial amount of specialized data in advance. Due to the seasonality and uncertainty of many crop pathogeneses, as well as some rare diseases or rare species, such data requirements are difficult to meet, leading to difficulties in achieving high levels of detection accuracy. Here, we use kiwifruit trunk bacterial canker (Pseudomonas syringae pv. actinidiae) as an example and propose a high-precision detection method to address the issue mentioned above. We introduce a lightweight and efficient image generative model capable of generating realistic and diverse images of kiwifruit trunk disease and expanding the original dataset. We also utilize the YOLOv8 model to perform disease detection; this model demonstrates real-time detection capability, taking only 0.01 s per image. The specific contributions of this study are as follows: (1) a depth-wise separable convolution is utilized to replace part of ordinary convolutions and introduce noise to improve the diversity of the generated images; (2) we propose the GASLE module by embedding a GAM, adjust the importance of different channels, and reduce the loss of spatial information; (3) we use an AdaMod optimizer to increase the convergence of the network; and (4) we select a real-time YOLOv8 model to perform effect verification. The results of this experiment show that the Fréchet Inception Distance (FID) of the proposed generative model reaches 84.18, having a decrease of 41.23 compared to FastGAN and a decrease of 2.1 compared to ProjectedGAN. The mean Average Precision (mAP@0.5) on the YOLOv8 network reaches 87.17%, which is nearly 17% higher than that of the original algorithm. These results substantiate the effectiveness of our generative model, providing a robust strategy for image generation and disease detection in plant kingdoms.

Occurrence Regionalization of Kiwifruit Brown Spot in Sichuan.

Kiwifruit brown spot caused by Corynespora cassiicola is the most significant fungal disease in Sichuan, resulting in premature defoliation, which had a significant impact on yield and fruit quality. The objective of the study was to determine the occurrence regularity and suitability of kiwifruit brown spot in Sichuan. The occurrence of the disease in the main producing region was continuously monitored, the maximum entropy (MaxEnt) model was used to predict its potential distribution, and the key environmental variables were identified using the jackknife method. The results indicated that kiwifruit brown spot was widely distributed across the entire producing region in Sichuan, predominantly affecting the variety "Hongyang". The incidence (p < 0.01) and disease index (p < 0.05) showed a significant positive correlation with the cultivar, and decreased with the altitude increasing. The average area under the ROC curve (AUC) of 10 replicates was 0.933 ± 0.012, with an accuracy of 84.44% in a field test, confirming the reliability of the predicted results. The highly suitable distribution areas of kiwifruit brown spot were mainly located in the Chengdu and Ya'an regions. The entire Panzhihua region was an unsuitable distribution area, and the entire Pujiang County and Mingshan District were highly suitable distribution areas. The key environmental variables affecting the potential distribution of kiwifruit brown spot included isothermality (24.3-33.7%), minimum temperature in August (16.3-23.6 °C), maximum temperature in July (25.5-31.2 °C), minimum temperature in June (15.6-20.9 °C), precipitation in August (158-430 mm), and average temperature in October (15.6-18.8 °C). This study provides a theoretical basis for the reasonable layout of the cultivar and the precise prevention and control of the disease.

How accompanying ions affect soil heavy metal removal by polyepoxysuccinic acid during washing?

Soil washing with green eluent is an efficient technique to remediate heavy metal contaminated farmland. In addition to eluent, less is known about the roles of accompanying ions on heavy metal removal. We investigated the effects of accompanying ions including Fe3+, Mn2+, Ca2+, Mg2+, Al3+, Si4+ and PO43- on the desorption of Pb2+ and Cd2+ in paddy and arid soils using ethylenediaminetetraacetic acid and polyepoxysuccinic acid as eluents. The release rates of target and accompanying ions showed significant fast and slow reaction stages based on corresponding analysis and kinetic models. In fast reaction stage, Pb2+ and Cd2+ performed geochemical analogy with Ca2+, Mg2+ and PO43-. The release curves of these ions were fitted well with Elovich model, indicating that they released from oxysalt surface into solution via ion exchange, and dissolution of Fe/Mn/Al/Si (hydr)oxides through H+- and ligand-promoted dissolution. In slow reaction stage, Pb2+ and Cd2+ were related to Fe3+, Mn2+, Al3+ and Si4+, which were controlled by intraparticle diffusion process. H+ slowly diffused into interlayer of phyllosilicates to displace target and accompanying ions by ion exchange. Therefore, this research filled the gap of accompanying ions driving the release behavior of heavy metal ions during leaching.

Global molecular evolution and phylogeographic analysis of barley yellow dwarf virus based on the cp and mp genes.

Barley yellow dwarf virus (BYDV) has caused considerable losses in the global production of grain crops such as wheat, barley and maize. We investigated the phylodynamics of the virus by analysing 379 and 485 nucleotide sequences of the genes encoding the coat protein and movement protein, respectively. The maximum clade credibility tree indicated that BYDV-GAV and BYDV-MAV, BYDV-PAV and BYDV-PAS share the same evolutionary lineage, respectively. The diversification of BYDV arises from its adaptability to vector insects and geography. Bayesian phylogenetic analyses showed that the mean substitution rates of the coat and movement proteins of BYDV ranged from 8.327 × 10- 4 (4.700 × 10- 4-1.228 × 10- 3) and 8.671 × 10- 4 (6.143 × 10- 4-1.130 × 10- 3) substitutions/site/year, respectively. The time since the most recent common BYDV ancestor was 1434 (1040-1766) CE (Common Era). The Bayesian skyline plot (BSP) showed that the BYDV population experienced dramatic expansions approximately 8 years into the 21st century, followed by a dramatic decline in less than 15 years. Our phylogeographic analysis showed that the BYDV population originating in the United States was subsequently introduced to Europe, South America, Australia and Asia. The migration pathways of BYDV suggest that the global spread of BYDV is associated with human activities.

Identification and Genetic Characterization of Pseudomonas syringae pv. actinidiae from Kiwifruit in Sichuan, China.

Pseudomonas syringae pv. actinidiae causes kiwifruit bacterial canker and poses a major threat to the kiwifruit industry. This study aimed to investigate the genetic characteristics of the P. syringae pv. actinidiae population from kiwifruit in Sichuan, China. Sixty-seven isolates obtained from diseased plants were characterized using morphological features, multiplex-PCR, and multilocus sequence analysis (MLSA). The isolates exhibited the typical colony morphology of P. syringae pv. actinidiae. Multiplex PCR amplification identified every isolate as P. syringae pv. actinidiae biovar 3. MLSA of the three housekeeping genes gapA, gyrB, and pfk, revealed that the reference strains of the five described biovars were clearly distinguished by a combined phylogenetic tree, and all of the tested isolates clustered with the reference strains of P. syringae pv. actinidiae biovar 3. Through a phylogenetic tree constructed from a single gene, it was found that pkf gene alone could distinguish biovar 3 from the other biovars. Furthermore, all P. syringae pv. actinidiae isolates analyzed by BOX-A1R-based repetitive extragenic palindromic (BOX)-PCR and enterobacterial repetitive intergenic consensus (ERIC)-PCR clustered into four groups. The clustering results of BOX- and ERIC-PCR indicated that group III had the largest number of isolates, accounting for 56.72 and 61.19% of all 67 isolates, respectively, and the two characterization methods were similar and complementary. The results of this study revealed that the genomes of P. syringae pv. actinidiae isolates from Sichuan had rich genetic diversity but no obvious correlation was found between clustering and geographical region. This research provides novel methodologies for rapidly detecting kiwifruit bacterial canker pathogen and a molecular differentiation at genetic level of P. syringae pv. actinidiae biovar diversity in China.

Validation of target protein PcnWAS in Pomacea canaliculata and screening of target-based molluscicidal compounds.

Virtual screening is an efficient way to obtain new drugs, which has become an important method in the field of pesticide research. Protein neural wiskott-Aldrich syndrome isoform X1 (PcnWAS) is a target protein that exists in the haemocytes of Pomacea canaliculata, and in this study, isothermal titration calorimetry (ITC) was used to evaluate the binding ability of protein PcnWAS and pedunsaponin A in vitro. Furthermore, it was set as a receptor, and the design of molluscicidal compounds based on protein PcnWAS was carried out. Results showed that, pedunsaponin A had high binding capacity with protein PcnWAS, and the binding constant (Ka) was 2.98 ± 1.74 × 10-4. A new potential molluscicidal compound thionicotinamide-adenine-dinucleotide (thionicotinamide-DPN) was obtained by virtual screening. In-vivo bioassay indicated that, the LC50 value was 57.7102 mg/L (72 h), and the oxygen consumption rate, ammonia excretion rate, oxygen nitrogen ratio and hemocyanin content of P. canaliculata declined after 60 mg/L thionicotinamide-DPN treated. Furthermore, the treatment of thionicotinamide-DPN also decreased gene expression level of protein PcnWAS. The results of ITC test showed that thionicotinamide-DPN can bind with protein PcnWAS efficiently, which means that it has the same target with pedunsaponin A when interacted with P. canaliculata. All the above results lay a foundation for the development of new molluscicides.

Discovery of a Potential Molluscicide Based on Protein PcRoo in Gill Cilia of Pomacea canaliculata.

In modern pesticide discovery, target-based drug design is an attractive and cost-effective approach. Previous studies found that protein rootletin (PcRoo) is a target protein of arecoline, when interacted with Pomacea canaliculata. In this study, we modeled the target protein through threading, and the binding energy between arecoline and protein PcRoo was calculated as -5.02 kcal/mol by molecular docking. Furthermore, two target compounds, baclofen and acedoben, with molluscicidal activity in theory were obtained by virtual screening in database DrugBank. The in vivo bioassay showed that baclofen could induce typical poisoning symptoms on P. canaliculata, which were characterized by weakness of foot muscles and loss of gill cilia, and the LC50 value was 16.2437 mg/L (72 h). Additionally, after 15 mg/L baclofen treatment, the oxygen consumption rate, ammonia excretion rate, and oxygen nitrogen ratio of P. canaliculata declined. Furthermore, the treatment of baclofen also decreased the gene expression level of PcRoo. These trends were the same as the changes after 5 mg/L arecoline treatment. The pharmacophore characteristics were further analyzed, and the results showed that the chemical structures of baclofen and arecoline were correlated in molluscicidal activity. These findings indicate that baclofen has the potential to be used as a molluscicide in agricultural production, and other new molluscicides may be obtained by virtual screening based on protein PcRoo.

First Report of Colletotrichum fructicola Causing Anthracnose on Glycine max in China.

Soybean (Glycine max L.) is one of the important oilseed and vegetable crop worldwide and provides the main source of vegetable oil and proteins for human and livestock (Hartman et al. 2011). In October 2021, approximately 35% of soybean pods suffered from anthracnose in the farmer's field in Chongzhou, Sichuan Province, China (103°40'12"E, 30°37'48"N), and the occurrence area accounted for about 3.3 hm2. Symptoms of soybean were characterized by yellow spots at the initial stage, gradually expanded into dark brown spots, and eventually amounts of small black particles were densely arranged in the wheel shape on dead spots. Diseased spots of soybean pods were cut into pieces and sequentially sterilized in 75% alcohol for 30 s, 4% sodium hypochlorite for 30 s, sterile water for 3 times. After that, these pieces were placed on potato dextrose agar (PDA), and incubated at 25±2°C in the dark for 5-7 days. Single spore was separately picked and transferred to a fresh PDA plate to obtain pure culture isolates. Total six pure isolates were collected, and among them the hyphae of representative isolate 8-B were initially white, turned grey gradually on PDA medium, and the colonial reverse were radiating, whorled or a mixture of both. Conidia of 8-B were septate, hyaline, unicellular, cylindrical, obtusely rounded at both ends with 1 or 2 oil balls inside, and 10.5-17.6 µm in length and 7.0 µm-3.6 µm in width (n=100). The conidial appressoria were brown subspherical, 6.9 µm-13.3 µm in length and 5.6 µm-10.1 µm (n=50) in width. Based on morphological and cultural characteristics, the isolate 8-B was tentatively identified as Colletotrichum gloeosporioides species complex（Weir et al. 2012). To test pathogenicity, the mycelial plugs were inoculated on 20 detached soybean pods at full seed (R6) stage, and three areas of each pod were lightly scratched using a needle prior to inoculation. As controls, the PDA plugs were attached to the pinned-treated pods. Three independent replicates were conducted for control and inoculated pods, respectively. All pods were incubated in a greenhouse at 25 ± 2°C with a relative humidity of approximately 90%. After 4-5 days post-inoculation, typical anthracnose lesions were observed on the inoculated pods while the control pods remained healthy only with small wound spots. The pathogen re-isolated from all the inoculated pods were morphologically identical to the inoculation isolate (8-B). For further molecular verification, the six gene fragments including the internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), chitin synthase 1 (CHS-1), actin (ACT), ß-tubulin 2 (TUB2) and calmodulin (CAL) were amplified and sequenced (Weir et al. 2012, Damm et al. 2012), and the obtained sequences were deposited in GenBank (Accession numbers ON960278, ON685214, ON964475, ON974476, ON685215 and ON964477, respectively). All six gene sequences of 8-B had a high identity to C. fructicola (the stand isolate ICMP 18581) with the accession numbers ON960278 (100%), ON974476 (96%), ON685214 (99%), ON964475 (99%), ON685215 (100%), and ON964477 100%), respectively. Anthracnose disease caused by C. fructicola has previously been reported to affect a range of plant hosts worldwide (Guarnaccia et al. 2017). However, it is still unknown on C. fructicola causing anthracnose in soybean in China. This study firstly reports C. fructicola as the causal agent of anthracnose on soybean in the country, and provides a theoretical basis for the diagnosis and control of this disease.

Pestalotiopsis Species Associated with Blueberry Leaf Spots and Stem Cankers in Sichuan Province of China.

Blueberry leaf spots and stem cankers caused by Pestalotiopsis spp. have become a serious threat for the production of blueberry in Sichuan Province. To characterize the etiology of the diseases connected with these fungi, samples showing leaf spot and stem canker symptoms were collected from the 12 main blueberry-growing areas of Sichuan Province from 2015 to 2020 and used for pathogen isolation. In total, 91 fungal isolates were obtained with preliminary morphological identification and 48 representative strains were selected for further pathogenicity test and molecular identification. Four species, including Pestalotiopsis clavispora (Neopestalotiopsis clavispora) (57.14%), P. trachicarpicola (28.57%), P. chamaeropis (13.19%), and P. adusta (1.10%), were identified based on conidial morphology, cultural characteristics, and phylogenetic analysis of the internal transcribed spacer region, partial sequence of the ß-tubulin gene, and the translation elongation factor 1-α. Pathogenicity tests showed that four species were pathogenic to leaves and stems of blueberry. Among them, P. clavispora (N. clavispora) was the most aggressive as the predominant species to cause both leaf spot and stem canker. P. trachicarpicola and P. chamaeropis were mainly isolated from leaves but also pathogenic to stems. P. adusta was only isolated from stems but also pathogenic to leaves. To the best of our knowledge, this is the first report of P. chamaeropis and P. adusta as pathogens causing leaf spots and stem canker on blueberry. The results provide helpful information in disease diagnosis and management of blueberry.

Comparison and Correlation of Corynespora cassiicola Populations from Kiwifruit and Other Hosts Based on Morphology, Phylogeny, and Pathogenicity.

Corynespora leaf spot, which is caused by Corynespora cassiicola (Berk. & M. A. Curtis) C.T. Wei (C. cassiicola), has been globally reported in many plant species. 'Hongyang' was reported as highly sensitive kiwifruit cultivar to C. cassiicola. This cultivar is an important germplasm resource in the Actinidiaceae family and is widely cultivated throughout China. Even though C. cassiicola has been identified as the pathogen associated with kiwifruits in China, the C. cassiicola population from kiwifruit has not been characterized based on morphology, phylogeny, and pathogenicity. In this study, 133 and 48 representative C. cassiicola isolates from kiwifruit and 11 other hosts, respectively, recovered from symptomatic leaves were classified into eight morphological subgroups based on host origins. Using three loci (rDNA ITS, caa5, and act1), a phylogenetic tree showed that C. cassiicola isolates in Sichuan Province were grouped into three clades. All kiwifruit isolates were genetically identical to the rubber isolates from different countries. However, most isolates from other hosts in this study were genetically identical to the cucumber, soybean, and cowpea isolates in China, Brazil, and the United States, and two strawberry isolates clustered with isolates from tomato and other hosts in China, Brazil, and the United States. Furthermore, we confirmed host shift of C. cassiicola among different plant species in this study. Although 51 isolates from kiwifruit and different hosts were pathogenic to kiwifruit, blueberry, cucumber, and soybean, virulence levels of the pathogen were diverse for four hosts. Kiwifruit isolates exhibited host specificity with regards to the original host in degree. In addition, those isolates revealed a correlation between morphology and pathogenicity. The results suggest that C. cassiicola in Sichuan Province were derived from three different phylogenetic lineages. Promotion of the susceptible 'Hongyang' cultivar led to the emergence of a regnant C. cassiicola population from kiwifruit. In conclusion, rapid development of the C. cassiicola-sensitive crop in agricultural systems led to the emergence of a regnant C. cassiicola population. In some dominant populations (e.g., the C. cassiicola population from kiwifruit in this study), host origin was found to be a key factor influencing the morphologic, genetic, and pathogenic characterization of C. cassiicola.

Diversity of Trichoderma species associated with soil in the Zoige alpine wetland of Southwest China.

The ecology of soil fungi is poorly understood, and recent comprehensive reports on Trichoderma are unavailable for any region, including the Zoige alpine wetland ecological region in China. One hundred soil samples were collected from different soil types and soil layers in Zoige alpine wetland ecological regions. Using the traditional suspension plating method, 80 Trichoderma strains were chosen to analyze species diversity. After a preliminary classification of morphological characteristics and the genes glyceraldehyde-3-phosphate dehydrogenase (gpd), 57 representative strains were selected and eventually identified as seven species via phylogenetic analyses of multilocus sequences based on the genes transcription elongation factor 1 alpha (tef1), encoding RNA polymerase II subunit B (rpb2) and ATP citrate lyase (acl1). Among them, T. harzianum was the dominant species isolated from five soil layers and four soil types, and had the highest isolation frequency (23%) in this zone, while T. polysporum and T. pyramidale were rare species, with isolation frequencies of less than 1%. Our detailed morphological observation and molecular phylogenetic analyses support the recognition of Trichoderma zoigense was described for the first time as a new species, while T. atrobrunneum as a new record for China was found. Our results will be used as a reference for a greater understanding of soil microbial resources, ecological rehabilitation and reconstructions in the Zoige alpine wetland.

Study on the relationship of Hsp70 with the temperature sensitivity of pedunsaponin A poisoning Pomacea canaliculata.

Previous studies have found that temperature influences molluscicidal the activity of pedunsaponin A (PA), which may be related to the expression of Hsp70, a cold-tolerance gene in Pomacea canaliculata. We determined the temperature effect of PA and the relationship between Hsp70 and temperature sensitivity of P. canaliculata poisoned by PA. Toxicity tests resulted in LC50 values of 17.7239 mg⋅L-1 at 10 °C, which decreased to 2.5774 mg⋅L-1 at 30 °C, implying a positive correlation between toxicity of PA and temperature. After Hsp70 being interfered, the mortality rate of P. canaliculata treated with PA for 72 h was 70%, which was significantly higher than that of snails treated with PA for 72 h without interfering (56.7%). Meanwhile, immune enzyme activities such as SOD, ACP and AKP were significantly increased in the interfered group and expression level of PcAdv in the gill was also significantly increased. These results suggest that deletion of Hsp70 promotes the activation of some immune enzymes of P. canaliculata and elevates the content of target proteins to cope with the dual stresses of low temperatures and molluscicides. These findings indicate that the Hsp70 plays an important role in influencing the temperature sensitivity of P. canaliculata when treated with PA.

Physiological and metabolic analyses provide insight into soybean seed resistance to fusarium fujikuroi causing seed decay.

Seed-borne pathogens cause diverse diseases at the growth, pre- and post-harvest stage of soybean resulting in a large reduction in yield and quality. The physiological and metabolic aspects of seeds are closely related to their defense against pathogens. Recently, Fusarium fujikuroi has been identified as the dominant seed-borne fungi of soybean seed decay, but little information on the responses of soybean seeds induced by F. fujikuroi is available. In this study, a time-course symptom development of seed decay was observed after F. fujikuroi inoculation through spore suspension soaking. The germination rate and the contents of soluble sugar and soluble protein were significantly altered over time. Both chitinase and ß-1,3-glucanase as important fungal cell wall-degrading enzymes of soybean seeds were also rapidly and transiently activated upon the early infection of F. fujikuroi. Metabolic profile analysis showed that the metabolites in glycine, serine, and threonine metabolism and tryptophan metabolism were clearly induced by F. fujikuroi, but different metabolites were mostly enriched in isoflavone biosynthesis, flavone biosynthesis, and galactose pathways. Interestingly, glycitein and glycitin were dramatically upregulated while daidzein, genistein, genistin, and daidzin were largely downregulated. These results indicate a combination of physiological responses, cell wall-related defense, and the complicated metabolites of soybean seeds contributes to soybean seed resistance against F. fujikuroi, which are useful for soybean resistance breeding.

Maize-soybean relay strip intercropping reshapes the rhizosphere bacterial community and recruits beneficial bacteria to suppress Fusarium root rot of soybean.

Rhizosphere microbes play a vital role in plant health and defense against soil-borne diseases. Previous studies showed that maize-soybean relay strip intercropping altered the diversity and composition of pathogenic Fusarium species and biocontrol fungal communities in the soybean rhizosphere, and significantly suppressed soybean root rot. However, whether the rhizosphere bacterial community participates in the regulation of this intercropping on soybean root rot is not clear. In this study, the rhizosphere soil of soybean healthy plants was collected in the continuous cropping of maize-soybean relay strip intercropping and soybean monoculture in the fields, and the integrated methods of microbial profiling, dual culture assays in vitro, and pot experiments were employed to systematically investigate the diversity, composition, and function of rhizosphere bacteria related to soybean root rot in two cropping patterns. We found that intercropping reshaped the rhizosphere bacterial community and increased microbial community diversity, and meanwhile, it also recruited much richer and more diverse species of Pseudomonas sp., Bacillus sp., Streptomyces sp., and Microbacterium sp. in soybean rhizosphere when compared with monoculture. From the intercropping, nine species of rhizosphere bacteria displayed good antagonism against the pathogen Fusarium oxysporum B3S1 of soybean root rot, and among them, IRHB3 (Pseudomonas chlororaphis), IRHB6 (Streptomyces), and IRHB9 (Bacillus) were the dominant bacteria and extraordinarily rich. In contrast, MRHB108 (Streptomyces virginiae) and MRHB205 (Bacillus subtilis) were the only antagonistic bacteria from monoculture, which were relatively poor in abundance. Interestingly, introducing IRHB3 into the cultured substrates not only significantly promoted the growth and development of soybean roots but also improved the survival rate of seedlings that suffered from F. oxysporum infection. Thus, this study proves that maize-soybean relay strip intercropping could help the host resist soil-borne Fusarium root rot by reshaping the rhizosphere bacterial community and driving more beneficial microorganisms to accumulate in the soybean rhizosphere.

Research on the molluscicidal activity and molecular mechanisms of arecoline against Pomacea canaliculata.

Pomacea canaliculata, as an invasive snail in China, can adversely affect agricultural crop yields, ecological environment, and human health. In this paper, we studied the molluscicidal activity and mechanisms of arecoline against P. canaliculata. The molluscicidal activity tests showed that arecoline exhibits strong toxicity against P. canaliculata, and the LC50 value (72 h) was 1.05 mg/L (15 ± 2 mm shell diameter). Additionally, Molluscicidal toxicity were negatively correlated with the size of snails. Snails (25 ± 2 mm shell diameter) were choosed for mechanisms research and the result of microstructure and biochemistry showed that arecoline (4 mg/L, 20 â„ƒ) had strong toxic effect on the gill, and the main signs were the loss of cilia in the gill filaments. Moreover, arecoline significantly decreased the oxygen consumption rate, ammonia excretion rate and inhibited acetylcholinesterase (AChE). Then, the changes in protein expression were studied by iTRAQ, and 526 downregulated proteins were found. Among these, cilia and flagella-associated 157-like (PcCFP) and rootletin-like (PcRoo) were selected as candidate target proteins through bioinformatics analysis, and then RNA interference (RNAi) was adopted to verify the function of PcCFP and PcRoo. The results showed that after arecoline treated, the mortality and the cilia shedding rate of PcRoo RNAi treated group was significantly lower than control group. The above results indicate that arecoline can bind well with protein PcRoo, and then leads to the drop of gill cilia, affect respiratory metabolism, accelerate its entry into hemolymph, inhibit AChE and finally leads to the death of P. canaliculata.