Anti-phytopathogenic Activity Research Articles

Isolation of Heavy Metal-Tolerant and Anti-Phytopathogenic Plant Growth-Promoting Bacteria from Soils.

In this study, by isolating multifunctional soil bacteria that can promote plant development, resist heavy metals, exhibit anti-phytopathogenic action against plant diseases, and produce extracellular enzymes, we hope to improve the effectiveness of phytoremediation techniques. To isolate multifunctional soil bacteria, we used soils with diverse characteristics as isolation sources. To look into the diversity and structural traits of the bacterial communities, We conducted amplicon sequencing of the 16S rRNA gene on five types of soils and predicted functional genes using Tax4Fun2. The isolated bacteria were evaluated for their multifunctional capabilities, including heavy metal tolerance, plant growth promotion, anti-phytopathogenic activity, and extracellular enzyme activity. The genes related to plant growth promotion and anti-phytopathogenic activity were most abundant in forest and paddy soils. Burkholderia sp. FZ3 and FZ5 demonstrated excellent heavy metal resistance (≤ 1 mM Cd and ≤ 10 mM Zn), Pantoea sp. FC24 exhibited the highest protease activity (24.90 μmol tyrosine·g-DCW-1·h-1), and Enterobacter sp. PC20 showed superior plant growth promotion, especially in siderophore production. The multifunctional bacteria isolated using traditional methods included three strains (FC24, FZ3, and FZ5) from the forest and one strain (PC20) from paddy field soil. These results indicate that, for the isolation of beneficial soil microorganisms, utilizing target gene information obtained from isolation sources and subsequently exploring target microorganisms is a valuable strategy.

Pseudomonas consortium improves soil health and alleviates cadmium (Cd) toxicity in Brassica juncea L. via biochemical and in silico approaches

The exponential rise in Cd in the environment has raised concerns for its adequate remediation worldwide. Its non-biodegradable nature and highly migratory feature make it more toxic. Plant growth-promoting rhizobacteria (PGPR) have shown great potential in the remediation of Cd-polluted agricultural lands. PGPR is comparatively efficient, convenient and economical. PGPR application enhances plant growth and development by conferring direct and indirect benefits. This study aimed to evaluate bacterial strains, Pseudomonas putida (Pp) and Pseudomonas fluorescens (Pf), for their PGPR traits, soil physiochemical analyses, and physiological and anatomical traits of B. juncea under Cd stress. Results showed that both microbial strains shared positive interaction and had minimum inhibitory concentration (MIC) ranging from 0.8mM and 0.6mM values for Pp and Pf respectively. P. fluorescens displayed better anti-phytopathogenic activity against pathogenic fungal strains (Alterneria brassicae, Alterneria brassicola, Verticillium longisporum, Fusarium oxysporum) than P. putida. They also synthesised plant growth regulators (PGRs) such as IAA (0.146,0.156μg/ml) and GA (2.062, 2.074 μg/ml). The co-inoculation of strains improved soil organic C, P, N, and K by 283.01 %, 100.42 %, 8.89 % and 40.38 %. Also, the interactive effect of Pp and Pf recovered dry matter content (DMC) by 18.13 % in comparison to Cd-stressed plants. Moreover, the strains reduced Cd-induced H2O2 production by DAB (340.38’-3’ diaminobenzidine) staining and hence restored membrane integrity. Also, in Cd-treated B. juncea plants, the anatomical characteristics were negatively affected. However, inoculated strains induce maximum recovery as indicated by well-developed vascular elements. Genes associated with PGPR traits were mined from the NCBI database. The information compiled thereafter indicated that the genes, galU, CadR, and pgl were responsible for biofilm formation, Cd resistance and lactone synthesis. In conclusion, we reported a promising consortium having PGPR traits, that improve soil and B. juncea health under Cd toxicities. Hence, the use of such bioinoculants can be a safer substitute for chemical fertilizers.

Isolation and characterization of plant growth-promoting bacteria from medicinal plants Java cardamom (Amomum compactum) and bitter ginger (Zingiber zerumbet)

Abstract. Geraldi A, Clement C, Pertiwi MD, Lestari Y, Parinnata DH, Arsad RN, Sadikin RA, Luqman A, Santoso H, Kristanti AN, Manuhara YSW, Wibowo AT. 2024. Isolation and characterization of plant growth-promoting bacteria from medicinal plants Java cardamom (Amomum compactum) and bitter ginger (Zingiber zerumbet). Biodiversitas 25: 2556-2564. Java cardamom (Amomum compactum) and bitter ginger (Zingiber zerumbet) are valuable medicinal plants native to Indonesia with significant economic and pharmacological importance. While their pharmacological properties have been extensively studied, little is known about the role of their endophytic bacterial communities in influencing plant growth and development. Understanding the interactions between these plants and their associated bacteria could provide insights into novel strategies to enhance their cultivation. This study investigates the potential of endophytic bacteria associated with A. compactum and Z. zerumbet in promoting plant growth. Samples were collected from leaf, rhizome, and rhizosphere soil, followed by isolation and characterization of bacterial strains. Molecular identification revealed the presence of Methylobacterium aquaticum, Paenibacillus tyrfis, Priestia megaterium strain 1, Priestia aryabhattai, and Microbacterium arthrosphaerae among the isolated strains from A. compactum, while strains isolated from Z. zerumbet included Enterobacter mori, Pr. megaterium strain 2, and Pr. megaterium strain 3. Those results demonstrated that Pr. megaterium strains exhibited strong phosphate solubilization, nitrogen fixation, and cellulolytic activity, while Pr. aryabhattai and Pa. tyrfis showed significant nitrogen fixation and cellulolytic potential. Additionally, M. aquaticum, Pa. tyrfis, and Pr. aryabhattai exhibited anti-phytopathogenic activity against Xanthomonas campestris. These findings not only highlight the diverse beneficial attributes of the isolated bacterial strains but also suggest their potential application as biofertilizers and biocontrol agents in agriculture, offering a promising avenue for sustainable farming practices.

Antifungal activity of bio-active cell-free culture extracts and volatile organic compounds (VOCs) synthesised by endophytic fungal isolates of Garden Nasturtium

Antimicrobial resistance in fungal pathogens (both human and plant) is increasing alarmingly, leading to massive economic crises. The existing anti-fungal agents are becoming ineffective, and the situation worsens on a logarithmic scale. Novel antifungals from unique natural sources are highly sought to cope sustainably with the situation. Metabolites from endophytic microbes are the best-fitted alternatives in this case. Endophytes are the untapped sources of ‘plants’ internal microbial population’ and are promising sources of effective bio-therapeutic agents. Fungal endophytes were isolated from Tropaeolum majus and checked for antifungal activity against selected plant and human pathogens. Bioactive metabolites were identified through chromatographic techniques. The mode of action of those metabolites was evaluated through various spectroscopic techniques. The production of antifungal metabolite was optimized also. In particular VOCs (volatile organic compounds) of TML9 were tested in vitro for their anti-phytopathogenic activity. Ethyl acetate (EA) extract of cell-free culture components of Colletotrichum aenigma TML3 exhibited broad-spectrum antifungal activity against four species of Candida and the major constituents reported were 6-pentyl-2H-pyran-2-one, 2-Nonanone, 1 propanol 2-amino. The volatile metabolites, trans-ocimene, geraniol, and 4-terpinyl acetate, produced from Curvularia lunata TML9, inhibited the growth of some selected phyto pathogens. EA extract hampered the biofilm formation, minimised the haemolytic effect, and blocked the transformation of Candida albicans (MTCC 4748) from yeast to hyphal form with a Minimum Fungicidal Concentration (MFC) of 200–600 µg mL−1. Central carbohydrate metabolism, ergosterol synthesis, and membrane permeability were adversely affected and caused the lethal leakage of necessary macromolecules of C. albicans. Volatile metabolites inhibited the growth of phytopathogens i.e., Rhizoctonia solani, Alternaria alternata, Botrytis cinerea, Cercospora beticola, Penicillium digitatum, Aspergillus fumigatus, Ceratocystis ulmi, Pythium ultimum up to 89% with an IC50 value of 21.3–69.6 µL 50 mL−1 and caused leakage of soluble proteins and other intracellular molecules. Citrusy sweet odor volatiles of TML9 cultured in wheat-husk minimised the infections of Penicillium digitatum (green mold), in VOC-exposed sweet oranges (Citrus sinensis). Volatile and non-volatile antifungal metabolites of these two T. majus endophytes hold agricultural and pharmaceutical interests. Metabolites of TML3 have strong anti-Candida activity and require further assessment for therapeutic applications. Also, volatile metabolites of TML9 can be further studied as a source of antifungals. The present investigational outcomes bio-prospects the efficacy of fungal endophytes of Garden Nasturtium.

The cryptic metabolites and anti-phytopathogenic activities from Nigrospora lacticolonia and Penicillium rubens uncovered by the synergism with host Paris polyphylla, monoculture, and co-culture

The synergism of host Paris polyphylla medium, the monoculture, and the coculture led to seventeen new metabolites, including eight sesquiterpenes, 1–7 having uncommon structural motifs compared to similar caryophyllene derivatives, 8 with an unprecedented bicyclic framework, and three xyloketals (13–15) with unprecedented frameworks from Nigrospora lacticolonia; one polyketide, 17 with novel bicyclo [2.2.2] undecane skeleton, and five polyketide-terpenoid hybrids, 20 (one novel sulfated), 21–24 from Penicillium rubens. The structures were determined mainly by the NMR, HRESIMS, ECD calculation, and single-crystal X-ray diffraction. Nine cryptic compounds (2–4, 5, 12–15, 17) were produced by the inductions of host medium and the coculture. The compounds 13 from N. lacticolonia, 24–26, 28, 29, and 31 from P. rubens indicated significant antiphytopathogenic activities against N. lacticolonia with MICs at 2–4 μg/mL. Moreover, compounds 22–26, 28, 29, and 31 from P. rubens showed antifungal activities against P. rubens with MICs at 2–4 μg/mL. The synergistic effects of host medium and the coculture can induce the structural diversity of metabolites.

The fungal protease BbAorsin contributes to growth, conidiation, germination, virulence, and antiphytopathogenic activities in Beauveria bassiana (Hypocreales: Cordycipitaceae)

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is one of the most destructive agricultural pests. The entomopathogenic fungus Beauveria bassiana (Hypocreales: Clavicipitaceae) is a biopesticide widely used for biocontrol of various pests. Secreted fungal proteases are critical for insect cuticle destruction and successful infection. We have previously shown that the serine protease BbAorsin in B. bassiana has entomopathogenic and antiphytopathogenic activities. However, the contribution of BbAorsin to fungal growth, conidiation, germination, virulence and antiphytopathogenic activities remains unclear. In this study, the deletion (ΔBbAorsin), complementation (Comp), and overexpression (BbAorsinOE) strains of B. bassiana were generated for comparative studies. The results showed that ΔBbAorsin exhibited slower growth, reduced conidiation, lower germination rate, and longer germination time compared to WT and Comp. In contrast, BbAorsinOE showed higher growth rate, increased conidiation, higher germination rate and shorter germination time. Injection of BbAorsinOE showed the highest virulence against S. frugiperda larvae, while injection of ΔBbAorsin showed the lowest virulence. Feeding BbAorsinOE resulted in lower pupation and adult eclosion rates and malformed adults. 16S rRNA sequencing revealed no changes in the gut microbiota after feeding either WT or BbAorsinOE. However, BbAorsinOE caused a disrupted midgut, leakage of gut microbiota into the hemolymph, and upregulation of apoptosis and immunity-related genes. BbAorsin can disrupt the cell wall of the phytopathogen Fusarium graminearum and alleviate symptoms in wheat seedlings and cherry tomatoes infected with F. graminearum. These results highlight the importance of BbAorsin for B. bassiana and its potential as a multifunctional biopesticide.

The Impact of the Culture Regime on the Metabolome and Anti-Phytopathogenic Activity of Marine Fungal Co-Cultures.

Co-cultivation, coupled with the OSMAC approach, is considered an efficient method for expanding microbial chemical diversity through the activation of cryptic biosynthetic gene clusters (BGCs). As part of our project aiming to discover new fungal metabolites for crop protection, we previously reported five polyketides, the macrolides dendrodolides E (1) and N (2), the azaphilones spiciferinone (3) and 8α-hydroxy-spiciferinone (4), and the bis-naphtho-γ-pyrone cephalochromin (5) from the solid Potato Dextrose Agar (PDA) co-culture of two marine sediment-derived fungi, Plenodomus influorescens and Pyrenochaeta nobilis. However, some of the purified metabolites could not be tested due to their minute quantities. Here we cultivated these fungi (both axenic and co-cultures) in liquid regime using three different media, Potato Dextrose Broth (PDB), Sabouraud Dextrose Broth (SDB), and Czapek-Dox Broth (CDB), with or without shaking. The aim was to determine the most ideal co-cultivation conditions to enhance the titers of the previously isolated compounds and to produce extracts with stronger anti-phytopathogenic activity as a basis for future upscaled fermentation. Comparative metabolomics by UPLC-MS/MS-based molecular networking and manual dereplication was employed for chemical profiling and compound annotations. Liquid co-cultivation in PDB under shaking led to the strongest activity against the phytopathogen Phytophthora infestans. Except for compound 1, all target compounds were detected in the co-culture in PDB. Compounds 2 and 5 were produced in lower titers, whereas the azaphilones (3 and 4) were overexpressed in PDB compared to PDA. Notably, liquid PDB co-cultures contained meroterpenoids and depside clusters that were absent in the solid PDA co-cultures. This study demonstrates the importance of culture regime in BGC regulation and chemical diversity of fungal strains in co-culture studies.

Chitosan embedded with ZnO nanoparticles and hydroxyapatite: synthesis, antiphytopathogenic activity and effect on tomato grown under high density

This study aimed to the synthesis of the new composite ZnOHap@Cs made with ZnO nanoparticles, hydroxyapatite and chitosan, and to examine its effect on tomato grown under normal conditions or under high density in the greenhouse. In addition, its antimicrobial activities were assessed in vitro against several fungal phytopathogens, and in planta against Pseudomonas syringae pv. tomato, the causal agent of bacterial speck disease of tomato. Results showed that ZnOHap@Cs was able to reduce radial growth of Fusarium oxysporum f.sp. melonis and Alternaria solani by more than 75 and 67%, respectively. Furthermore, the composite revealed to be effective in reducing disease severity of bacterial speck when used as a foliar spray. Our study showed that the variety of tomato, Campbell 33, was affected by shade generated when grown at high density, as evidenced by increased plant height, stem thinning, decreased root biomass, and reduced photosynthetic pigments and net photosynthesis. ZnOHap@Cs treatment enhanced root biomass, content of photosynthetic pigments, and net photosynthesis of tomato when grown under low density. However, most of these variables were maintained in pre-treated plants when they grow at high density. These results highlight that ZnOHap@Cs improves partly plant physiological properties to cope with the effect of shade, and it could be used as effective fungicides for sustainable health plant protection.

Anticancer and Antiphytopathogenic Activity of Fluorinated Isatins and Their Water-Soluble Hydrazone Derivatives.

A series of new fluorinated 1-benzylisatins was synthesized in high yields via a simple one-pot procedure in order to explore the possible effect of ortho-fluoro (3a), chloro (3b), or bis-fluoro (3d) substitution on the biological activity of this pharmacophore. Furthermore, the new isatins could be converted into water-soluble isatin-3-hydrazones using their acid-catalyzed reaction with Girard's reagent P and its dimethyl analog. The cytotoxic action of these substances is associated with the induction of apoptosis caused by mitochondrial membrane dissipation and stimulated reactive oxygen species production in tumor cells. In addition, compounds 3a and 3b exhibit platelet antiaggregation activity at the level of acetylsalicylic acid, and the whole series of fluorine-containing isatins does not adversely affect the hemostasis system as a whole. Among the new water-soluble pyridinium isatin-3-acylhydrazones, compounds 7c and 5c,e exhibit the highest antagonistic effect against phytopathogens of bacterial and fungal origin and can be considered useful leads for combating plant diseases.

Synthesis and Antiphytopathogenic Activity of Novel Oxazolidine-2,4-diones Bearing Phenoxypyridine Moiety.

In the present study, we conducted optimization of pyramoxadone and synthesized a series of novel oxazolidinediones. Antifungal assays showed that these compounds exhibited moderate to excellent antifungal activity against various pathogens. Further SAR analysis revealed that the introduction of substituents to the benzene ring of the phenoxy group or the inclusion of bulky groups, such as tert-butyl, on the aniline moiety, had a detrimental effect on the activity. However, the inclusion of fluorine atoms in the aniline moiety significantly enhanced the antifungal efficacy. Notably, compound 2-4 displayed significantly higher activity compared to both pyramoxadone and famoxadone against R. solani, B. cinerea, S. sclerotiorum, and P. oryzae, where it demonstrated EC50 values of 1.78, 2.47, 2.33, and 2.23 μg/mL, respectively. Furthermore, compound 2-4 exhibited potent protective and curative effects against the tomato gray mold in vivo. A mechanistic investigation revealed that compound 2-4 significantly impacted the mycelial morphology, inhibited spore germination, and impeded mycelial respiration, ultimately leading to the inhibition of pathogenic fungus growth. These findings indicate that compound 2-4 has the potential to serve as a cyt bc1 inhibitor and should be further investigated for development.

Dual RNA Sequencing of Beauveria bassiana-Infected Spodoptera frugiperda Reveals a Fungal Protease with Entomopathogenic and Antiphytopathogenic Activities.

Insect pests and phytopathogens significantly impact crop yield and quality. The fall armyworm (FAW) Spodoptera frugiperda and the phytopathogen Fusarium graminearum cause substantial economic losses in crops like barley and wheat. However, the entomopathogen Beauveria bassiana shows limited efficacy against FAW, and its antiphytopathogenic activities against F. graminearum remain unclear. Here, dual RNA sequencing was performed to identify differentially expressed genes in B. bassiana-infected FAW larvae. We found that the BbAorsin gene was significantly upregulated at 36 and 48 h post-infection. BbAorsin encodes a serine-carboxyl protease and is mainly expressed in blastospores and hyphae. Overexpression of BbAorsin in B. bassiana ARSEF2860 enhanced virulence against Galleria mellonella and FAW larvae and inhibited F. graminearum growth. The recombinant BbAorsin protein induced apoptosis and necrosis in FAW hemocytes and inhibited F. graminearum spore germination. These findings shed light on transcriptomic mechanisms governing insect-pathogen interactions, which could aid in developing dual-functional entomopathogens and anti-phytopathogens.

A step forward in sustainable pesticide production from Amphidinium carterae biomass via photobioreactor cultivation with urea as a nitrogen source

This study addresses the problem of replacing nitrate and ammonium with urea as a greener nitrogen source in the mass cultivation of the microalga Amphidinium carterae for the development of amphidinol-based phytosanitary products. To solve this problem, a nuclear magnetic resonance assisted investigation evaluated the effect of nitrogen sources on growth and metabolic profiles in photobioreactors. Urea-fed cultures exhibited growth kinetics comparable to nitrate-fed cultures (µmax = 0.30 day−1, Pbmax = 43 mgL-1day−1). Urea-fed cultures had protein, lipid, and carbohydrate contents of 39.5%, 14.5%, and 42.4%, respectively, while nitrate-fed cultures had 27.9 %, 17.5% and 48.1%, respectively. Metabolomics revealed nitrogen source-dependent metabotypes and a correlation between amphidinols and polyunsaturated fatty acids. The amphidinol-to-nitrogen yield coefficient in urea-fed cultures (135 mg/g) was approximately 2.5 times higher than in nitrate-fed cultures. The potent antiphytopathogenic activity exhibited by extracts from urea-fed cultures underscores the potential of urea as a sustainable nitrogen source in microalgae-based biorefineries.

Anti-phytopathogenic activity and the mechanisms of phthalides from Angelica sinensis (Oliv.) Diels.

The resistance of traditional chemical fungicides to plant pathogenic fungi and the threats to the safety of humans and the environment highlight an urgent need to find safe and efficient alternatives to chemical fungicides. Owing to the wide spectrum of antifungal activities, low persistence and nontoxicity to mammals and aquatic life, essential oils have considerable potential as low-risk pesticides. In this study, the essential oil and the main components of Angelica sinensis (Oliv.) Diels (Danggui) were extracted, analyzed by GC-MS, and evaluated for their antifungal activities against six plant pathogenic fungi. 3-butylidenephthalide (3-BPH) showed the best antifungal activity against Fusarium graminearum with an EC50 value of 14.35 μg mL-1 . The antifungal mechanistic studies revealed that 3-BPH induced the generation of endogenous ROS to cause lipid peroxidation of the cell membrane and inhibited the biosynthesis of ergosterol, thereby causing the cell membranedamaged to exert its fungicidal activity. Significantly, 3-BPH could reduce deoxynivalenol production compared to the control. This study demonstrated the potent fungicidal activity of natural phthalide compound 3-BPH and highlighted its potential as an alternative agent to control F. graminearum. © 2023 Society of Chemical Industry.

New Inspiration of 1,3,4-Oxadiazole Agrochemical Candidates: Manipulation of a Type III Secretion System-Induced Bacterial Starvation Mechanism to Prevent Plant Bacterial Diseases

Discovering new anti-virulent agents to control plant bacterial diseases by preventing bacterial pathogenesis/pathogenicity rather than affecting bacterial growth is a sensible strategy. However, the effects of compound-manipulated bacterial virulence factors on host response are still not clear. In this work, 35 new 1,3,4-oxadiazole derivatives were synthesized and systematically evaluated for their anti-phytopathogenic activities. Bioassay results revealed that compound C7 possessed outstanding antibacterial activity in vitro (half-maximal effective concentration: 0.80 μg/mL) against Xanthomonas oryzae pv. oryzae (Xoo) and acceptable bioactivity in vivo toward rice bacterial leaf blight. Furthermore, virulence factor-related biochemical assays showed that C7 was a promising anti-virulent agent. Interestingly, C7 could indirectly reduce the inducible expression of host SWEET genes and thereby alleviate nutrient supply in the infection process of phytopathogenic bacteria. Our results highlight the potential of 1,3,4-oxadiazole-based agrochemicals for manipulating type III secretion system-induced phytopathogenic bacteria starvation mechanisms to prevent plant bacterial diseases.

Antifungal, Antiviral, and HPLC Analysis of Phenolic and Flavonoid Compounds of Amphiroa anceps Extract

The increasing use of chemical control agents and pesticides to prevent plant disease has resulted in several human and environmental health problems. Seaweeds, e.g., Amphiroa anceps extracts, have significant antimicrobial activities against different human pathogens. However, their anti-phytopathogenic activities are still being investigated. In the present investigation, three fungal isolates were isolated from root rot and grey mold symptomatic strawberry plants and were molecularly identified by ITS primers to Fusarium culmorum, Rhizoctonia solani, and Botrytis cinerea with accession numbers MN398396, MN398398, and MN398400, respectively. In addition, the organic extract of the red alga Amphiroa anceps was assessed for its antifungal activity against the three identified fungal isolates and tobacco mosaic virus (TMV) infection. At 100 µg/mL, the A. anceps extract had the best biological activity against R. solani, B. cinerea, and TMV infection, with inhibition rates of 66.67%, 40.61%, and 81.5%, respectively. Contrarily, the A. anceps extract exhibited lower activity against F. culmorum, causing inhibition in the fungal mycelia by only 4.4% at the same concentration. The extract’s HPLC analysis revealed the presence of numerous phenolic compounds, including ellagic acid and gallic acid, which had the highest concentrations of 19.05 and 18.36 µg/mL, respectively. In this line, the phytochemical analysis also showed the presence of flavonoids, with the highest concentration recorded for catechin at 12.45 µg/mL. The obtained results revealed for the first time the effect of the A. anceps extract against the plant fungal and viral pathogens, making the seaweed extract a promising source for natural antimicrobial agents.

Mushroom-Derived Novel Selenium Nanocomposites' Effects on Potato Plant Growth and Tuber Germination.

Multicomponent materials, where nanosized selenium (Se) is dispersed in polymer matrices, present as polymer nanocomposites (NCs), namely, selenium polymer nanocomposites (SeNCs). Selenium as an inorganic nanofiller in NCs has been extensively studied for its biological activity. More ecologically safe and beneficial approaches to obtain Se-based products are the current challenge. Biopolymers have attained great attention with perspective multifunctional and high-performance NCs exhibiting low environmental impact with unique properties, being abundantly available, renewable, and eco-friendly. Composites based on polysaccharides, including beta-glucans from edible and medicinal mushrooms, are bioactive, biocompatible, biodegradable, and have exhibited innovative potential. We synthesized SeNCs on the basis of the extracellular polysaccharides of several medicinal mushrooms. The influence of bio-composites from mushrooms on potato plant growth and tuber germination were studied in two potato cultivars: Lukyanovsky and Lugovskoi. Bio-composites based on Grifola umbellata demonstrated the strongest positive effect on the number of leaves and plant height in both cultivars, without negative effect on biomass of the vegetative part. Treatment of the potato tubers with SeNC from Gr. umbellata also significantly increased germ length. Potato plants exposed to Se-bio-composite from Ganoderma lucidum SIE1303 experienced an increase in the potato vegetative biomass by up to 55% versus the control. We found earlier that this bio-composite was the most efficient against biofilm formation by the potato ring rot causative agent Clavibacter sepedonicus (Cms). Bio-composites based on Pleurotus ostreatus promoted increase in the potato root biomass in the Lugovskoi cultivar by up to 79% versus the control. The phytostimulating ability of mushroom-based Se-containing bio-composites, together with their anti-phytopathogenic activity, testifies in favor of the bifunctional mode of action of these Se-biopreparations. The application of stimulatory green SeNCs for growth enhancement could be used to increase crop yield. Thus, by combining myco-nanotechnology with the intrinsic biological activity of selenium, an unexpectedly efficient tool for possible applications of SeNCs could be identified.

Talaromarins A-F: Six New Isocoumarins from Mangrove-Derived Fungus Talaromyces flavus TGGP35.

Six new isocoumarin derivative talaromarins A-F (1–6), along with 17 known analogues (7–23), were isolated from the mangrove-derived fungus Talaromyces flavus (Eurotiales: Trichocomaceae) TGGP35. Their structures were identified by detailed IR, UV, 1D/2D NMR and HR-ESI-MS spectra. The absolute configurations of new compounds were determined by the modified Mosher’s method and a comparison of their CD spectra with dihydroisocoumarins described in the literature. The antioxidant, antibacterial, anti-phytopathogenic and inhibitory activity against α-glucosidase of all the isolated compounds were tested. Compounds 6–11, 17–19 and 21–22 showed similar or better antioxidant activity than the IC50 values ranging from 0.009 to 0.27 mM, compared with the positive control trolox (IC50 = 0.29 mM). Compounds 10, 18, 21 and 23 exhibited strong inhibitory activities against α-glucosidase with IC50 values ranging from 0.10 to 0.62 mM, while the positive control acarbose had an IC50 value of 0.5 mM. All compounds showed no antibacterial or anti-phytopathogenic activity at the concentrations of 50 μg/mL and 1 mg/mL, respectively. These results indicated that isocoumarins will be useful to developing antioxidants and as diabetes control agents.

Biotransformation of Waste Bile Acids: A New Possible Sustainable Approach to Anti-Fungal Molecules for Crop Plant Bioprotection?

Phytopathogenic fungi are among the main causes of productivity losses in agriculture. To date, synthetic chemical pesticides, such as hydroxyanilides, anilinopyrimidines and azole derivatives, represent the main treatment tools for crop plant defence. However, the large and uncontrolled use of these substances has evidenced several side effects, namely the resistance to treatments, environmental damage and human health risks. The general trend is to replace chemicals with natural molecules in order to reduce these side effects. Moreover, the valorisation of agri-food industry by-products through biotransformation processes represents a sustainable alternative to chemical synthesis in several sectors. This research is aimed at comparing the anti-phytopathogenic activity of waste bovine and porcine bile with secosteroids obtained by biotransformation of bile acids with Rhodococcus strains. The ultimate goal is to apply these natural products on food crops affected by phytopathogenic fungi.

Macrophytic waste optimization by synthesis of silver nanoparticles and exploring their agro-fungicidal activity

Enormous quantities of marine macrophytes have been accumulated in shorelines by tidal actions, which considered as organic pollution. There is a necessity to collect macrophytic biomasses from shorelines to protect the environment. This paper focused on the collection and utilization of waste macrophytic biomass for the production of silver nanoparticles. Two representative candidates, Cymodocea serrulata (Seagrass) and Padina australis (Seaweed) were selected for the study. Synthesized nanoparticles were characterized by UV-Spectrophotometer, FTIR, SEM, EDS and AFM and their anti-phytopathogenic activity also assessed. Results of this study revealed that C. serrulata mediated silver nanoparticles (Cs-AgNP) exhibited effective anti-fungal activity against Pyriporia oryzea (14 ± 1.5 mm), Helminthisporium oryzea (12 ± 1.4 mm), Alternaria sp. (10 ± 1.2 mm) and Padina australis mediated silver nanoparticles (Pa-AgNPs) showed potential activity against Rhizoctonia solani (16 ± 1.6 mm), Xanthomanas oryzae (15 ± 1.3 mm). The current study findings could pave a way to collect the organic waste from shorelines and deploying them for the production of value added products.

Induction of Isochromanones by Co-Cultivation of the Marine Fungus Cosmospora sp. and the Phytopathogen Magnaporthe oryzae.

Microbial co-cultivation is a promising approach for the activation of biosynthetic gene clusters (BGCs) that remain transcriptionally silent under artificial culture conditions. As part of our project aiming at the discovery of marine-derived fungal agrochemicals, we previously used four phytopathogens as model competitors in the co-cultivation of 21 marine fungal strains. Based on comparative untargeted metabolomics analyses and anti-phytopathogenic activities of the co-cultures, we selected the co-culture of marine Cosmospora sp. with the phytopathogen Magnaporthe oryzae for in-depth chemical studies. UPLC-MS/MS-based molecular networking (MN) of the co-culture extract revealed an enhanced diversity of compounds in several molecular families, including isochromanones, specifically induced in the co-culture. Large scale co-cultivation of Cosmospora sp. and M. oryzae resulted in the isolation of five isochromanones from the whole co-culture extract, namely the known soudanones A, E, D (1-3) and their two new derivatives, soudanones H-I (4-5), the known isochromans, pseudoanguillosporins A and B (6, 7), naphtho-γ-pyrones, cephalochromin and ustilaginoidin G (8, 9), and ergosterol (10). Their structures were established by NMR, HR-ESIMS, FT-IR, electronic circular dichroism (ECD) spectroscopy, polarimetry ([α]D), and Mosher’s ester reaction. Bioactivity assays revealed antimicrobial activity of compounds 2 and 3 against the phytopathogens M. oryzae and Phytophthora infestans, while pseudoanguillosporin A (6) showed the broadest and strongest anti-phytopathogenic activity against Pseudomonas syringae, Xanthomonas campestris, M. oryzae and P. infestans. This is the first study assessing the anti-phytopathogenic activities of soudanones.