First Report of Plumed Cockscomb (Celosia argentea var. plumosa) Stem Blight Caused by Phytophthora nicotianae in Taiwan.

Celosia spp. is a widely cultivated ornamental plant in gardens or parks in Taiwan. In September 2021, withering leaves and grayish-brown lesions were observed on the lower stem of plumed cockscombs (C. argentea var. plumosa) in Taichung City, with an incidence of about 22% in 136 plants after continuous precipitation, impacting the aesthetic value of the landscape. Symptomatic plants were collected, surface disinfected with 70% EtOH for ~20 sec., blotted dried, and excised diseased tissues (~ 3×3 mm2) were placed on 2% water agar. Four representative isolates were obtained after purification and the colonies were white with aerial and non-septated hyphae on V8 agar for 7 days. Sporangia were ovoid, ellipsoid or obpyriform, papillate, (26.3-55.9) 38.0 × 29.0 (20.1-40.6) µm (n = 200) (Ahonsi et al. 2007). Chlamydospores were spherical, terminal or intercalary, 26.0 (15.1-40.4) µm (n = 200). All isolates belong to A2 mating type with amphigynous antheridia and plerotic oospores, 21.0 (17.7-25.7) µm (n = 200), resembling the descriptions of Phytophthora (Erwin & Ribeiro 1996). For molecular identification, sequences of the ITS, ß-tubulin (ß-tub), and EF-1α regions of all isolates were amplified using ITS1/ITS4, TUBUF2/TUBUR1, and ELONGF1/ELONGR1 primers, respectively (White et al. 1990; Kroon et al. 2004). BLAST analyses of isolates cap1-2 (ITS: OQ581785; ß-tub: OQ590022; EF-1α: OQ590026), cap1-3 (ITS: OQ581786; ß-tub: OQ590023; EF-1α: OQ590027), cap2-1 (ITS: OQ581787; ß-tub: OQ590024; EF-1α: OQ590028), and cap2-2 (ITS: OQ581788; ß-tub: OQ590025; EF-1α: OQ590029) showed 100% of ITS identity, 99.5 to 99.9% of ß-tub identity, and 99.4 to 99.6% of EF-1α identity with Phytophthora nicotianae (ITS: MG865551; ß-tub: MH493987; EF-1α: MH359043). Phylogenetic trees were constructed using concatenated ITS, ß-tub, and EF-1α sequences based on maximum likelihood with a GTR+G model in MEGA X and Bayesian inference method in Geneious Prime 2022.2. All isolates were clustered in P. nicotianae with similar topology, thereby were identified as P. nicotianae. To confirm pathogenicity, 7 to 10-day-old seedlings and 6-week-old plumed cockscomb plants were inoculated in separate trials and each experiment was conducted twice. For each seedling, the lower stem was inoculated with 50 µl of zoospore suspension (104 zoospores/ml), 3 plants per isolate, and then incubated at 30±2℃ with 12 h light. For adult plants, each was inoculated with mycelial plugs from one V8 plate of 10-day-old P. nicotianae, 5 plants per isolate, and incubated at 25±2℃ in a greenhouse. Control plants were inoculated with sterile water and V8 agar plugs, respectively. Stem and root rot were observed on seedlings 4 days after inoculation while wilting and lower stem browning were observed on adult plants 2 months after inoculation. All control plants remained healthy at the end of repeated trials and identical pathogens were re-isolated only from symptomatic plants, thus fulfilling Koch's rules. P. nicotianae has been reported causing root rot and stem necrosis not only on cockscomb (C. plumosa Hort. ex Burvenich) in Argentina (Frezzi 1950), but also infecting several ornamental plants recently in Taiwan (Ann et al. 2018). To our knowledge, this is the first report of stem blight caused by P. nicotianae on plumed cockscombs in Taiwan. This finding suggests limited options for landscaping and the host preference of the isolates obtained in this study should warrant further studies.

Development of Specific Primers for Fusarium oxysporum Formae Speciales rapae and matthiolae with an Integrated Multiplex PCR for Distinguishing Four Formae Speciales on Brassicaceae.

There are four formae speciales of Fusarium oxysporum responsible for causing yellows of Brassicaceae. Because of crossbreeding among crops, the host ranges of these formae speciales often overlap, making pathogen identification a challenging task. Among these formae speciales, F. oxysporum f. sp. rapae and F. oxysporum f. sp. matthiolae still lack specific primers for pathogen identification. To address this problem, we targeted the secreted in xylem (SIX) genes, known as specific effectors of pathogenic F. oxysporum, for primer design. Through sequence comparison with other formae speciales, we successfully designed specific primers for F. oxysporum f. sp. rapae and F. oxysporum f. sp. matthiolae on SIX14 and SIX9, respectively. Both primer pairs exhibited high specificity in detecting F. oxysporum f. sp. rapae or F. oxysporum f. sp. matthiolae, distinguishing them from 20 nontarget formae speciales of F. oxysporum, five species of phytopathogenic Fusarium, and four other common pathogenic fungi affecting cruciferous plants. Moreover, the effectiveness of these specific primers was validated by detecting the pathogens in infected plants. To further enhance the identification process of the four formae speciales, we combined the two newly designed specific primer pairs with two previously published primer pairs, enabling the establishment of a multiplex PCR method that can accurately distinguish all four formae speciales of F. oxysporum responsible for causing yellows in cruciferous plants in a single reaction.

First Report of New Guinea Impatiens (Impatiens hawkeri) Leaf Spot Caused by Alternaria burnsii - A. tomato species complex in Taiwan.

New Guinea impatiens (Impatiens hawkeri) is a common ornamental crop usually planted in pots and planters, flower beds, home gardens, or parks in Taiwan. In June 2021, leaf spots on 87.1% (27/31) of potted I. hawkeri plants on National Chung Hsing University (NCHU) campus were observed. Initially, tiny chlorotic leaf spots were found, which aged into brown to grayish white necrotic spots with reddish-purple margins. The necrotic spots enlarged, coalesced, and formed concentric rings. To isolate the pathogen, diseased leaves were surface-disinfected with 70% ethanol for 15 seconds and blotted dry with a paper towel. Small pieces (~2×6 mm2) of tissues were excised from the junction of the lesions and healthy areas, placed onto 2% water agar, and incubated at 25°C with 12-h photoperiod for three days. Individual hyphal tips growing out of diseased tissues were transferred onto potato dextrose agar (PDA). Three isolates, OM10, OM43, and OM45, were obtained and grown on half-strength PDA at 28°C in the dark for at least two weeks. Conidia of each isolate produced on the half-strength PDA were washed off in sterile water with 0.01% of Tween 20. Pathogenicity tests were performed by spraying leaves of 2- to 3-month-old potted healthy I. hawkeri plants with 5 ml of conidial suspension (1 × 105 conidia/ml) of the three isolates, respectively. Control plants were sprayed with sterile water. There were four plants per treatment and the experiments were conducted twice. Inoculated plants were covered with plastic bags for two days and incubated in a greenhouse with a temperature range of 19 to 31°C. Leaf spots similar to those observed in the field were observed at 7 to 14 days after inoculation in both trials. The same fungus was isolated from inoculated plants, whereas control plants showed no symptoms. Thereafter, the three isolates were subjected to morphological and molecular identification. Colonies were brown to gray in the center and white in the border with abundant aerial mycelia. Conidia were brown, obclavate to ovoid, produced in single or branched chains, one to seven transverse and zero to three longitudinal septa. Conidial size of the three isolates ranged between 11.2 to 43.1 × 6.0 to 12.7 µm (n = 50 for each isolate). Conidiophores of the three isolates were dark-brown, septate, branched or unbranched, and measured 27.0 to 147.65 × 2.71 to 4.54 µm (n = 50 for each isolate). Based on the morphological characteristics, the three isolates were identified as Alternaria spp. (Simmons 2007). For molecular identification, the internal transcribed spacer (ITS) region, RNA polymerase II second largest subunit (RPB2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and major allergen Alt-a-1 gene (Alt-a-1) were amplified using primer pairs ITS1/ITS4 (White et al. 1990), RPB2-5F2/RPB2-7cR (Sung et al. 2007), gpd1/gpd2 (Berbee et al. 1999), and Alt-for/Alt-rev (Hong et al. 2005), respectively. Sequence analyses of isolates OM10 (ITS: GenBank Accession no. OP358436; RPB2: OP377483; GAPDH: OP377468; Alt-a-1: OP377471), OM43 (ITS: OP358437; RPB2: OP377484; GAPDH: OP377469; Alt-a-1: OP377472), and OM45 (ITS: OP358438; RPB2: OP377485; GAPDH: OP377470; Alt-a-1: OP377473) showed 100%, 99.61 to 100%, 99.65%, and 100% identities with a reference strain CBS 107.38 of A. burnsii for ITS (KP124420), RPB2 (KP124889), GAPDH (JQ646305), and Alt-a-1 (KP123967), respectively. They also showed 100%, 99.61 to 100%, 99.65%, and 99.58% identities with an A. tomato strain CBS 103.30 for ITS (KP124445), RPB2 (KP124915), GAPDH (KP124294), and Alt-a-1 (KP123991), respectively. Based on the morphological and sequence characteristics, the pathogen causing New Guinea impatiens leaf spot was identified as a member of the Alternaria burnsii - A. tomato species complex. The diseased plants on NCHU campus were destroyed. There have been no reports of the disease in other landscape areas or nurseries. To our knowledge, this is the first report of A. burnsii - A. tomato species complex causing New Guinea impatiens leaf spot in Taiwan. Since the pathogens in the species complex have been documented causing diseases on several important economic crops and the New Guinea impatiens is widely planted in nurseries and landscapes, the host range and the significance of the pathogen in agro-ecosystem may warrant further investigations.

Identification and Characterization of a Multifunctional Biocontrol Agent, Streptomyces griseorubiginosus LJS06, Against Cucumber Anthracnose.

Twenty-eight bacterial strains isolated from Chinese herb extracts, beer fermentation waste, and raw oyster shells were evaluated for their efficacy in controlling cucumber anthracnose. Four bacterial strains, namely TG01, TG02, LJS06, and LJS08, were found to effectively reduce the mycelial growth of Colletotrichum orbiculare COC3 on PDA media. Spraying or drenching LJS06 spore suspension before inoculation significantly p < 0.05 reduced disease severity; thus, LJS06 was subject to further characterization. On the basis of the morphological, physiological, and biochemical characteristics and a multilocus sequence analysis of partial 16S rRNA, atpD, rpoB, and trpB genes, LJS06 was identified to be Streptomyces griseorubiginosus (Ryabova and Preobrazhenskaya) Pridham et al. Physiological and biochemical tests revealed that S. griseorubiginosus LJS06 can produce amylase, cellulase, chitinase, protease, siderophore, polyamines, and indole-3-acetic acid. Thus, a culture filtrate of LJS06 (specifically SL06) was formulated and evaluated for its efficacy against conidial germination, appressorium formation, and anthracnose management. Diluted SL06 was found to significantly (p < 0.05) inhibit conidial germination and appressorium formation, which can be attributed to impaired membrane integrity, accumulated reactive oxygen species (ROS), and impaired energy metabolism in the conidia. In addition, the spraying and drenching of diluted SL06 before inoculation consistently and significantly (p < 0.05) reduced anthracnose severity. These results jointly suggest that S. griseorubiginosus LJS06 can aid in the management of cucumber anthracnose by directly inhibiting conidial function and priming the plant defense system.

Genomic and biochemical characterization of antifungal compounds produced by Bacillus subtilis PMB102 against Alternaria brassicicola.

Bacillus subtilis is ubiquitous and capable of producing various metabolites, which make the bacterium a good candidate as a biocontrol agent for managing plant diseases. In this study, a phyllosphere bacterium B. subtilis PMB102 isolated from tomato leaf was found to inhibit the growth of Alternaria brassicicola ABA-31 on PDA and suppress Alternaria leaf spot on Chinese cabbage (Brassica rapa). The genome of PMB102 (Accession no. CP047645) was completely sequenced by Nanopore and Illumina technology to generate a circular chromosome of 4,103,088 bp encoding several gene clusters for synthesizing bioactive compounds. PMB102 and the other B. subtilis strains from different sources were compared in pangenome analysis to identify a suite of conserved genes involved in biocontrol and habitat adaptation. Two predicted gene products, surfactin and fengycin, were extracted from PMB102 culture filtrates and verified by LC-MS/MS. The antifungal activity of fengycin was tested on A. brassicicola ABA-31 in bioautography to inhibit hyphae growth, and in co-culturing assays to elicit the formation of swollen hyphae. Our data revealed that B. subtilis PMB102 suppresses Alternaria leaf spot by the production of antifungal metabolites, and fengycin plays an important role to inhibit the vegetative growth of A. brassicicola ABA-31.

Field Sanitation and Foliar Application of Streptomyces padanus PMS-702 for the Control of Rice Sheath Blight.

Rice sheath blight (ShB), caused by Rhizoctonia solani Kühn AG1-IA, is one of the destructive rice diseases worldwide. The aims of this study were to develop biocontrol strategies focusing on field sanitation and foliar application with a biocontrol agent for ShB management. Streptomyces padanus PMS-702 showed a great antagonistic activity against R. solani. Fungichromin produced by S. padanus PMS-702, at 3.07 mg/l inhibited 50% mycelial growth, caused leakage of cytoplasm, and inhibited the formation of infection structures of R. solani. Fungichromin could reach to 802 mg/l when S. padanus PMS-702 was cultured in MACC broth for 6 days. Addition of 0.5% S. padanus PMS-702 broth into soil decreased the survival rate of the pathogen compared to the control. Soil amended with 0.5% S. padanus broth and 0.5% tea seed pomace resulted in the death of R. solani mycelia in the infested rice straws, and the germination of sclerotia was inhibited 21 days after treatment. Greenhouse trials revealed that S. padanus cultured in soybean meal-glucose (SMGC-2) medium after mixing with different surfactants could enhance its efficacy for inhibiting the pathogen. Of six surfactants tested, the addition of 2% tea saponin was the most effective in suppressing the pathogen. S. padanus broth after being fermented in SMGC-2, mixed with 2% tea saponin, diluted 100 fold, and sprayed onto rice plants significantly reduced ShB disease severity. Thus, S. padanus PMS-702 is an effective biocontrol agent. The efficacy of S. padanus PMS-702 for disease control could be improved through formulation.

Phenylacetic Acid and Methylphenyl Acetate From the Biocontrol Bacterium Bacillus mycoides BM02 Suppress Spore Germination in Fusarium oxysporum f. sp. lycopersici.

Bacillus mycoides strain BM02 originally isolated from the tomato rhizosphere was found to have beneficial functions in tomato by promoting plant growth and reducing the severity of Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (Fol). Cytological experiments demonstrated B. mycoides BM02 reduced Fol invasion by reducing spore attachment and increasing hyphal deformation in hydroponics-grown tomato root tissues. Two volatile antifungal compounds, phenylacetic acid (PAA) and methylphenyl acetate (MPA), were identified from the culture filtrates of B. mycoides BM02 by GC-MS analysis. Chemically synthesized PAA, and to a lower extent MPA, suppressed spore germination but have no effects on the hyphal growth of Fol. Our results indicated that the biocontrol agent B. mycoides BM02 produced an array of bioactive compounds including PAA and MPA to suppress plant diseases caused by Fol and other pathogenic microorganisms.

Degenerated Virulence and Irregular Development of Fusarium oxysporum f. sp. niveum Induced by Successive Subculture.

Successive cultivation of fungi on artificial media has been reported to cause the sectorization, which leads to degeneration of developmental phenotype, and virulence. Fusarium oxysporum f. sp. niveum (Fon), the causal agent of watermelon Fusarium wilt, forms degenerated sectors after successive cultivation. In the present research, we demonstrated that subculture with aged mycelia increased the incidence of degenerations. To further investigate the differences between the Fon wild type (sporodochial type, ST) and variants (MT: mycelial type and PT: pionnotal type), developmental phenotypes and pathogenicity to watermelon were examined. Results in variants (PT2, PT3, PT11, and MT6) were different from ST with mycelia growth, conidia production and chlamydospore formation. Virulence of degenerated variants on susceptible watermelon Grand Baby (GB) cultivar was determined after inoculation with Fon variants and Fon ST. In root dipping methods, Fon variants showed no significant differences in disease progress compared with ST. Fon variants showed a significant decrease in disease progression compared with ST through infested soil inoculation. The contrasting results of two inoculation methods suggest that the degenerative changes due to repeated successive cultivation may lead to the loss of pathogen virulence-related factors of the early stage of Fon infection process. Therefore, cell wall-degrading enzymes (CWDEs; cellulase, pectinase, and xylanase) activities of different variants were analyzed. All Fon degenerated variants demonstrated significant decreases of CWDEs activities compared with ST. Additionally, transcript levels of 9 virulence-related genes (fmk1, fgb1, pacC, xlnR, pl1, rho1, gas1, wc1, and fow1) were assessed in normal state. The degenerated variants demonstrated a significantly low level of tested virulence-related gene transcripts except for fmk1, xlnR, and fow1. In summary, the degeneration of Fon is triggered with successive subculture through aged mycelia. The degeneration showed significant impacts on virulence to watermelon, which was correlated with the reduction of CWDEs activities and declining expression of a set of virulence-related genes.

Brown Root Rot Disease of Phyllanthus myrtifolius: The Causal Agent and Two Potential Biological Control Agents.

Brown root rot (BRR), caused by Phellinus noxius (Corner) G. Cunningham, occurs on over 200 species of plants, especially woody trees and shrubs. Ceylon myrtle (Phyllanthus myrtifolius [Wight] Müll.Arg.), a common hedge plant, was recently observed to be infected with BRR. Disease diagnosis was performed by completing Koch's postulates, and Ceylon myrtle was confirmed to be a new host of P. noxius. Typical symptoms of BRR were observed, including reduction in leaf size, dieback of branches, and suspended growth of young leaves. A disease severity index was used to quantify BRR in this study. Compared with Malabar chestnut, Ceylon myrtle was relatively resistant to BRR. Surprisingly, phylogenetic analysis of the ITS and 28S sequences revealed that isolates identified as P. noxius from Taiwan and many other countries were clustered in the same clade but separate from the clade comprising isolates from China, which were designated Pyrrhoderma noxium based on P. noxius. Therefore, to temporarily distinguish these pathogens, the former clade was designated GPN (global P. noxius), whereas the latter clade was designated CPN (China Py. noxium). In biocontrol assays, Streptomyces padanus and Bacillus sp. were selected for BRR control of Ceylon myrtle. Disease severity was reduced from 0.51 to 0.37 by S. padanus and to 0.14 by Bacillus sp. in greenhouse trials. In addition, the two biocontrol agents, especially S. padanus, exhibited good growth-promoting effects on cuttings of Ceylon myrtle. With these double advantages, S. padanus and Bacillus sp. have great potential to control BRR in practical applications.

A Synergistic Effect of Chitosan and Lactic Acid Bacteria on the Control of Cruciferous Vegetable Diseases.

Two lactic acid bacteria (LAB) designated J02 and J13 were recovered from fermented vegetables based on their ability to suppress soft rot disease caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) on radish. J02 and J13 were identified as Lactobacillus pentosus and Leuconostoc fallax, respectively. The ability of J02 and J13 to suppress plant diseases is highly dependent on chitosan. LAB alone has no effect and chitosan alone has only a moderate effect on disease reduction. However, J02 or J13 broth cultures plus chitosan display a strong inhibitory effect against plant pathogens and significantly reduces disease severity. LAB strains after being cultured in fish surimi (agricultural waste) and glycerol or sucrose-containing medium and mixed with chitosan, reduce three cruciferous vegetable diseases, including cabbage black spot caused by Alternaria brassicicola, black rot caused by Xanthomonas campestris pv. campestris, and soft rot caused by Pcc. Experimental trials reveal that multiple applications are more effective than a single application. In-vitro assays also reveal the J02/chitosan mixture is antagonistic against Colletotrichum higginsianum, Sclerotium rolfsii, and Fusarium oxysporum f. sp. rapae, indicating a broad-spectrum activity of LAB/chitosan. Overall, our results indicate that a synergistic combination of LAB and chitosan offers a promising approach to biocontrol.

Fungichromin Production by Streptomyces padanus PMS-702 for Controlling Cucumber Downy Mildew.

Streptomyces padanus PMS-702 strain produces a polyene macrolide antibiotic fungichromin and displays antagonistic activities against many phytopathogenic fungi. In the present study, experimental formulations were assessed to improve the production of fungichromin, the efficacy of PMS-702 on the suppression of sporangial germination, and the reduction of cucumber downy mildew caused by Pseudoperonospora cubensis. PMS-702 strain cultured in a soybean meal-glucose (SMG) medium led to low levels of fungichromin accumulation and sporangial germination suppression. Increasing medium compositions and adding plant oils (noticeably coconut oil) in SMG significantly increased fungichromin production from 68 to 1,999.6 µg/ml. Microscopic examination reveals that the resultant suspensions significantly reduced sporangial germination and caused cytoplasmic aggregation. Greenhouse trials reveal that the application of PMS-702 cultural suspensions reduced downy mildew severity considerably. The addition of Tween 80 into the synthetic medium while culturing PMS-702 further increased the suppressive efficacy of downy mildew severity, particularly when applied at 24 h before inoculation or co-applied with inoculum. Fungichromin at 50 µg/ml induced phytotoxicity showing minor necrosis surrounded with light yellowish halos on cucumber leaves. The concentration that leads to 90% inhibition (IC90) of sporangial germination was estimated to be around 10 µg/ml. The results provide a strong possibility of using the S. padanus PMS-702 strain as a biocontrol agent to control other plant pathogens.

Application of palladium-modified zeolite for prolonging post-harvest shelf life of banana.

BACKGROUND: The marketability of banana is limited by the rapid rate of ripening. However, the traditional post-harvest technologies may not be desirable. The aim of this study was to investigate the potential of a reusable material for the food preservation industry. RESULTS: The nanocomposite-based palladium (Pd)-modified zeolite (Pd/zeolite) was prepared by impregnating Pd into zeolite. Pd/zeolite had a Brunauer-Emmett-Teller dinitrogen specific surface area of 475 m2 g-1 with crystal structure similar to Y-zeolite. Transmission electron microscopy images showed the dispersion of Pd particles over the multi-pore zeolite support. Pd/zeolite uniquely acted as an adsorbent and a catalyst and was able to remove ethylene even after reaching breakthrough point. To prove Pd/zeolite is reusable, a 99 ± 0.8% ethylene removal efficiency still remained even after five consecutive cycles with repeated use of Pd/zeolite. The presence of Pd/zeolite significantly decreased the ethylene concentration during 18 days of storage at 20 ± 2 °C. CONCLUSIONS: Pd/zeolite could delay the ripening of banana and improve its firmness and the peel color significantly. Findings indicated that the as-prepared Pd/zeolite is an effective adsorbent/catalyst with high potential for practical application in ethylene removal, especially for the post-harvest period. © 2019 Society of Chemical Industry.

Silver Nanoparticles on Nanoscale Silica Platelets (AgNP/NSP) and Nanoscale Silica Platelets (NSP) Inhibit the Development of Fusarium oxysporum f. sp. niveum.

Nanotechnology has attracted much attention recently because of its agricultural applications. In this study, we analyzed the ability of two potential nanomaterials (NMs), nanoscale silica platelets (NSP) and silver nanoparticles on nanoscale silica platelets (AgNP/NSP), to control Fusarium wilt [caused by Fusarium oxysporum f. sp. niveum (Fon)] disease in watermelon. Both AgNP/NSP and NSP significantly reduced Fon mycelial growth and spore viability. In addition, AgNP/NSP decreased the mycelium viability at concentrations of 150 and 200 ppm. Scanning and transmission electron microscopy showed significant morphological effects on Fon cells, such as increased roughness and interior hollowing after AgNP/NSP and NSP treatments. Further, fluorescence staining experiments showed that a concomitant increase in membrane permeability occurred after treatment with NMs. The biochemical effects of NM treatment included a significant reduction in secreted cellulase activity. Interestingly, the addition of cysteine as a reducing agent decreased effects of NSP on Fon spores, suggesting suppression of Fon spore development attributable to oxidative stress. Taken together, these results indicate that AgNP/NSP and NSP may potentially serve as nanofungicides for future control of Fusarium wilt and other fungal diseases.

Evaluation of Efficacy and Toxicity of Exfoliated Silicate Nanoclays as a Feed Additive for Fumonisin Detoxification.

The efficacy of nanosilicate clay platelets (NSCP), exfoliated silicates from natural montmorillonites, as a feed additive for ameliorating fumonisin B1 (FB1) toxicosis was evaluated. Toxicological mechanisms by NSCP were examined through proteomic and biochemical analyses. Dietary supplementation with NSCP at a low level of 40 mg/kg of feed improved growth performances in chickens with respect to FB1 toxicosis. Other issues of ameliorated symptoms including serum and/or hepatic aspartate aminotransferase activity, oxidative stress indicators, and sphinganine/sphingosine ratio, a hallmark of FB1 toxicosis, were considered. Chickens with NSCP inclusion alone at 1000 mg/kg of feed exhibited no changes in hepatic histology, oxidative status, and serum parameters and even had a higher feed intake. Proteomic analysis with liver tissues identified 45 distinct proteins differentially affected by FB1 and/or NSCP, in which proteins involved in thiol metabolism and redox regulation, glycolysis, carcinogenesis, and detoxification by glutathione S-transferase were promoted by FB1, whereas NSCP caused differential changes of protein abundances related to methionine/cysteine and choline/glycine interconversion for glutathione synthesis, redox regulation by peroxiredoxin, toxin/metabolite delivery by albumin, glycolysis, tricarboxylic acid cycle, adenosine triphosphate (ATP) synthesis, and chaperon escort for endoplasmic reticulum stress relief. Functional analyses confirmed the enhancement of hepatic metabolic processes for ATP and NAD(P)H production to meet the need for detoxification, antioxidative defense, and toxin/metabolite clearance by FB1 or NSCP ingestion. On the basis of the amelioration of FB1 toxicosis, global profile of hepatic protein expressions, and validated toxicological mechanisms, NSCP were concluded as a safe and effective agent for FB1 detoxification.

The Genetic Structure, Virulence, and Fungicide Sensitivity of Fusarium fujikuroi in Taiwan.

The rice disease bakanae, caused by Fusarium fujikuroi Nirenberg, has been present in Taiwan for over a century. To better understand the genetic diversity and structure of F. fujikuroi, a set of 16 polymorphic simple sequence repeat (SSR) markers were newly developed and used to analyze 637 F. fujikuroi isolates collected in 14 cities or counties around Taiwan from 1996 to 2013. On the basis of Bayesian clustering, the isolates were classified into four highly differentiated clusters: cluster B likely derived from the more widespread and genetically diversified clusters A or C, and cluster D was restricted to four cities or counties and may have been introduced from unknown sources genetically distinct from clusters A, B, and C. The coexistence of both mating types (MAT1-1:MAT1-2 = 1:1.88) and the highly diversified vegetative compatibility groups (VCG) (16 VCG among the 21 assessed isolates) suggest the likelihood of sexual reproduction in the field. However, the biased mating type ratios and linkage disequilibrium in the population suggest nonrandom mating between individuals. A significant pattern of isolation by distance was also detected, which implies a geographical restricted gene flow and low dissemination ability of F. fujikuroi. Evaluation of 24 representative isolates on eight rice varieties revealed differential levels of virulence, however no clear pattern of specific variety x isolate interaction was observed. Investigations of the differences in virulence and fungicide sensitivity between 8 early isolates (1998 and 2002) and 52 recent isolates (2012) indicate the evolution of increased resistance to the fungicide prochloraz in F. fujikuroi in Taiwan.

Expression of Five Endopolygalacturonase Genes and Demonstration that MfPG1 Overexpression Diminishes Virulence in the Brown Rot Pathogen Monilinia fructicola.

Monilinia fructicola is a devastating pathogen on stone fruits, causing blossom blight and fruit rot. Little is known about pathogenic mechanisms in M. fructicola and related Monilinia species. In this study, five endopolygalacturonase (endo-PG) genes were cloned and functionally characterized in M. fructicola. Quantitative reverse-transcriptase PCR (qRT-PCR) revealed that the five MfPG genes are differentially expressed during pathogenesis and in culture under various pH regimes and carbon and nitrogen sources. MfPG1 encodes the major endo-PG and is expressed to significantly higher levels compared to the other four MfPGs in culture and in planta. MfPG1 function during pathogenesis was evaluated by examining the disease phenotypes and gene expression patterns in M. fructicola MfPG1-overexpressing strains and in strains carrying the ß-glucuronidase (GUS) reporter gene fused with MfPG1 (MfPG1-GUS). The MFPG1-GUS reporter was expressed in situ in conidia and hyphae following inoculation of flower petals, and qRT-PCR analysis confirmed MfPG1 expression during pathogenesis. MfPG1-overexpressing strains produced smaller lesions and higher levels of reactive oxygen species (ROS) on the petals of peach and rose flowers than the wild-type strain, suggesting that MfPG1 affecting fungal virulence might be in part resulted from the increase of ROS in the Prunus-M. fructicola interactions.

Effects of ultrasonic and microwave pretreatments on lipid extraction of microalgae.

The extraction of lipids from microalgal cells using ultrasonic and microwave pretreatments is mechanistically evaluated based on the distribution of cell fragments, the lipid content analysis, the scanning electron microscopic (SEM) observation of ruptured microalgal cells, and the analysis of fatty acids. The results indicate that microwave pretreatment extracts lipids more rapidly and efficiently as compared to ultrasonic pretreatment. The rupture of cells in the microwave process is due to the tremendous pressure caused by the rapid heating of the moisture inside the microalgal cells, whereas in the ultrasonic process the microalgal cells are ruptured by shock waves from cavitation bubbles outside the cells. The fatty acid composition of the respective lipids extracted via the two types of pretreatment did not vary significantly from one another. These results demonstrate that the microwave process is rapid and more effective than the ultrasonic process for lipid extraction from microalgae.

Isolation and identification of secondary metabolites of Clitocybe nuda responsible for inhibition of zoospore germination of Phytophthora capsici.

Secondary metabolites of Clitocybe nuda displayed antimicrobial activity against Phytophthora capsici. The culture filtrate of C. nuda was extracted with ethanol and chromatographically separated on a Sephadex LH-20 column and fractionated on a silica gel column to give eight fractions. These fractions were tested for the ability to inhibit zoospore germination of P. capsici . The most active fraction was further purified by silica gel column chromatography to yield three compounds: 2-methoxy-5-methyl-6-methoxymethyl-p-benzoquinone (1), 6-hydroxy-2H-pyran-3-carbaldehyde (2), and indole-3-carbaldehyde (3), all new to C. nuda. At a concentration of 500 mg/L, compound 3 showed complete inhibition of zoospore germination, while compounds 1 and 2 showed inhibition rates of 97 and 86%, respectively. To our knowledge, compound 1 is a newly discovered compound and, for the other two compounds, this is the first report in C. nuda. These compounds are potential candidates for new edible fungi-derived pesticides for the control of plant diseases.

Determination of alachlor and its metabolite 2,6-diethylaniline in microbial culture medium using online microdialysis enriched-sampling coupled to high-performance liquid chromatography.

In this study, a simple and novel microdialysis sampling technique incorporating hollow fiber liquid phase microextraction (HF-LPME) coupled online to high-performance liquid chromatography (HPLC) for the one-step sample pretreatment and direct determination of alachlor (2-chloro-2',6'-diethyl-N -(methoxymethyl)acetanilide) and its metabolite 2,6-diethylaniline (2,6-DEA) in microbial culture medium has been developed. A reversed-phase C-18 column was utilized to separate alachlor and 2,6-DEA from other species using an acetonitrile/water mixture (1:1) containing 0.1 M phosphate buffer solution at pH 7.0 as the mobile phase. Detection was carried out with a UV detector operated at 210 nm. Parameters that influenced the enrichment efficiency of online HF-LPME sampling, including the length of the hollow fiber, the perfusion solvent and its flow rate, the pH, and the salt added in sample solution, as well as chromatographic conditions were thoroughly optimized. Under optimal conditions, excellent enrichment efficiency was achieved by the microdialysis of a sample solution (pH 7.0) using hexane as perfusate at the flow rate of 4 µL/min. Detection limits were 72 and 14 ng/mL for alachlor and 2,6-DEA, respectively. The enrichment factors were 403 and 386 (RSD < 5%) for alachlor and 2,6-DEA, respectively, when extraction was performed by using a 40 cm regenerated cellulose hollow fiber and hexane as perfusion solvent at the flow rate of 0.1 µL/min. The proposed method provides a sensitive, flexible, fast, and eco-friendly procedure to enrich and determine alachlor and its metabolite (2,6-DEA) in microbial culture medium.

Identification of the Solanum nigrum extract component involved in controlling cabbage black leaf spot disease.

In this study, we discovered that an ethanol (EtOH) extract of Solanum nigrum inhibited spore germination of Alternaria brassicicola, the causative agent of cabbage black leaf spot disease. At a concentration of 500 mg/L, this ethanol extract also caused the germ tubes to become completely swollen. Detached cabbage leaves were then used to evaluate the effects of the extract in controlling the disease. It was observed that the extract-induced swelling of A. brassicicola germ-tube spores did not cause the symptoms of black spot disease on cabbage leaves. Furthermore, an n-butanol fraction of the EtOH extract exhibited strong antifungal activity; at a concentration of 25 mg/L, a derived subfraction (Bu-11-13) showed complete inhibition of spore germination. A white powder was collected from fraction Bu-11-13, and its minimum inhibitory concentration was determined to be 8 mg/L. Using NMR and LC-MS/MS analysis, this white powder compound was identified as degalactotigonin.