Effect of glutathione biosynthesis-related modulators on the thiol redox state enzymes and on sclerotial differentiation of filamentous phytopathogenic fungi

In this study, sclerotial differentiation in filamentous phytopathogenic fungi, representing the four main types of sclerotia, was studied in relation to thiol redox state (TRS)-related enzymes and their substrates/products. TRS was altered by the general TRS modulator Ν-acetylcysteine (AcCSH) and by the glutathione (GSH) biosynthesis modulators l-oxo-thiazolidine-4-carboxylate (OTC), and l-buthionine-S,R-sulfoximine (BSO). This study showed that the four studied types of sclerotial differentiation are directly related with the antioxidant –SH groups of GSH and/or CSH, since the decrease of sclerotial differentiation concurred with an increase of these thiols by the GSH biosynthesis modulators AcCSH, OTC, and BSO. Supportive to that conclusion is the fact that, in general, the activities of the TRS-related enzymes GR/GPDH and Ttase decrease in the end of the undifferentiated stage due to the substitution of their antioxidant function by the antioxidant potential of the –SH group providers AcCSH and OTC. Moreover, it was found that BSO expectedly suppressed GSH biosynthesis in the tested fungi, and unexpectedly decreased their sclerotial differentiation by a dose-dependent manner typical for antioxidants. The possible antioxidant role of BSO was supported by the decrease it caused in the antioxidant enzymes GR/GPDH and Ttase. The results of this study are in accordance with our hypothesis that sclerotial differentiation in phytopathogenic fungi is induced by oxidative stress.     

Hydrogen peroxide is involved in the sclerotial differentiation of filamentous phytopathogenic fungi

Aims: The purpose of this study was to investigate the role of H₂O₂ and the related oxidative stress markers catalase (CAT) and lipid peroxidation in the sclerotial differentiation of the phytopathogenic filamentous fungi Sclerotium rolfsii, Sclerotinia minor, Sclerotinia sclerotiorum and Rhizoctonia solani. Methods and Results: Using the H₂O₂‐specific scopoletin fluorometric assay and the CAT‐dependent H₂O₂ consumption assays, it was found that the production rate of intra/extracellular H₂O₂ and CAT levels in the sclerotiogenic fungi were significantly higher and lower, respectively, than those of their nondifferentiating counterpart strains. They peaked in the transition between the undifferentiated and the differentiated state of the sclerotiogenic strains, suggesting both a cell proliferative and differentiative role. In addition, the indirect indicator of oxidative stress, lipid peroxidation, was substantially decreased in the nondifferentiating strains. Conclusions: These findings suggest that the differentiative role of H₂O₂ is expressed via induction of higher oxidative stress in the sclerotiogenic filamentous phytopathogenic fungi. Significance and Impact of the Study: This study shows that the direct marker of oxidative stress H₂O₂ is involved in the sclerotial differentiation of the phytopathogenic filamentous fungi S. rolfsii, S. minor, S. sclerotiorum and R. solani, which could have potential biotechnological implications in terms of developing antifungal strategies by regulating intracellular H₂O₂ levels.     

Effect of thiol redox state modulators on oxidative stress and sclerotial differentiation of the phytopathogenic fungus <Emphasis Type="Italic">Rhizoctonia solani</Emphasis>

This study showed that sclerotial differentiation in the filamentous phytopathogenic fungus Rhizoctonia solani is directly related to oxidative stress and thiol redox state (TRS). Sclerotial differentiation is modulated by the availability of non-cytotoxic −SH groups as was shown by the inhibition of sclerorial differentiation by the TRS modulator N-acetyl cysteine (AcCSH), and not necessarily with those of the TRS reduced components glutathione (GSH) and its precursor cysteine (CSH) as indicated by the GSH-biosynthesis inducer and inhibitor l-2–oxo-thiazolidine-4-carboxylate and l-buthionine-S,R-sulfoximine, respectively. Moreover, inhibition of sclerotial differentiation was accompanied by decrease of the high oxidative stress indicators, lipid peroxidation and DNA damage in the mycelial substrate where sclerotia initials are formed, which suggests that this phenomenon is related to oxidative stress as it is predicted by our theory on sclerotial differentiation.     

The development of antenna complexes of barley (Hordeum vulgare cv. Akcent) under different light conditions as judged from the analysis of 77 K chlorophyll a fluorescence spectra

Using 77 K chlorophyll a (Chl a) fluorescence spectra in vivo, the development was studied of Photosystems II (PS II) and I (PS I) during greening of barley under intermittent light followed by continuous light at low (LI, 50 μmol m⁻² s⁻¹) and high (HI, 1000 μmol m⁻² s⁻¹) irradiances. The greening at HI intermittent light was accompanied with significantly reduced fluorescence intensity from Chl b excitation for both PS II (F685) and PS I (F743), in comparison with LI plants, indicating that assembly of light-harvesting complexes (LHC) of both photosystems was affected to a similar degree. During greening at continuous HI, a slower increase of emission from Chl b excitation in PS II as compared with PS I was observed, indicating a preferred reduction in the accumulation of LHC II. The following characteristics of 77 K Chl a fluorescence spectra documented the photoprotective function of an elevated content of carotenoids in HI leaves: (1) a pronounced suppression of Soret region of excitation spectra (410–450 nm) in comparison with the red region (670–690 nm) during the early stage of greening indicated a strongly reduced excitation energy transfer from carotenoids to the Chl a fluorescing forms within PS I and PS II; (2) changes in the shape of the excitation band of Chl b and carotenoids (460–490 nm) during greening under continuous light confirmed that the energy transfer from carotenoids to Chl a within PS II remained lower as compared with the LI plants. This revised version was published online in June 2006 with corrections to the Cover Date.     

The role of ascorbic acid role in the differentiation of sclerotia in Sclerotinia minor

Sclerotinia minor in culture produces ascorbic acid in levels dependent on oxidative growth conditions and stage of development. During differentiation reduced/oxidized ascorbate ratio decreased by 12 and 6 fold at high and low oxidative stress, respectively. Exogenous ascorbate caused a concentration-dependent decrease of oxidative stress (lipid peroxidation), inhibition of sclerotial differentiation (up to 100%) and delay of differentiatlon (up to 10 days). Ascorbic acid may be produced to help the fungus reduce oxidative stress during growth. The data of this study support our theory proposing that oxidative stress is the inducing factor of sclerotial differentiation in fungi.This revised version was published online in October 2005 with corrections to the Cover Date.     

Thiol redox state and related enzymes in sclerotium-forming filamentous phytopathogenic fungi

Thiol redox state (TRS) reduced and oxidized components form profiles characteristic of each of the four main types of differentiation in the sclerotiogenic phytopathogenic fungi: loose, terminal, lateral-chained, and lateral-simple, represented by Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii, and Sclerotinia minor, respectively. A common feature of these fungi is that as their undifferentiated mycelium enters the differentiated state, it is accompanied by a decrease in the low oxidative stress-associated total reduced thiols and/or by an increase of the high oxidative stress-associated total oxidized thiols either in the sclerotial mycelial substrate or in its corresponding sclerotium, indicating a relationship between TRS-related oxidative stress and sclerotial differentiation. Moreover, the four studied sclerotium types exhibit high activities of TRS-related antioxidant enzymes, indicating the existence of antioxidant protection of the hyphae of the sclerotium medulla until conditions become appropriate for sclerotium germination.     

Phenotypic and biological properties of two antagonist <Emphasis Type="Italic">Bacillus subtilis</Emphasis> strains

Bacillus subtilis KB-1111 and KB-1122 were studied to illustrate their phenotypic and biological properties. Comparison of KB-1111 with KB-1122 in morphology was carried out by microscopy and agar plate assays. Biological assay of the test strains showed that they may possess different physiological pathways from those of reference strain ATCC6501. The assessment of antagonism against the indicator fungi showed that both test strains had broad antifungal characteristics against eight phytopathogenic fungi. Of those fungal species, Magnaporthe grisea P131, Sclerotinia sclerotiorum, and F. oxysporium exhibited high sensitivity to the test strains.     

Thiol redox state and oxidative stress affect sclerotial differentiation of the phytopathogenic fungi Sclerotium rolfsii and Sclerotinia sclerotiorum

Aims:  To investigate the involvement of oxidative stress and thiol redox state (TRS) in sclerotial differentiation of Sclerotium rolfsii and Sclerotinia sclerotiorum.
Methods and results:  Oxidative stress in these fungi was assessed by lipid peroxidation, which was higher in comparison with their nonsclerotiogenic counterpart strains. TRS [measured as glutathione (GSH) and cysteine] was associated with oxidative stress and differentiation using the TRS modulator and antioxidant Ν -acetylcysteine (AcCSH) and the GSH biosynthesis inducer and inhibitor l -2-oxo-thiazolidine-4-carboxylate and l -buthionine- S , R -sulphoximine (BSO) respectively. Differentiation and oxidative stress was decreased by AcCSH in both fungi. The decrease of differentiation by BSO was not associated with oxidative stress in these fungi.
Conclusions:  Differentiation and oxidative stress in both fungi depends on the availability of antioxidant noncytotoxic –SH groups and is not depended on any direct antioxidant role of GSH and its precursor cysteine.
Significance and Impact of the Study:  This study helps to understand the mechanism(s) of sclerotial differentiation in these agriculturally important phytopathogenic fungi and proposes that AcCSH can be used as potent fungicide by (i) acting as growth inhibiting cytotoxic oxidant and (ii) sustaining these fungi in their undifferentiated hyphal stage where they are vulnerable to degradation by soil micro-organisms.     

Non-gramineous hosts ofMyriosclerotinia borealis

On the basis of cultural, anatomical, and electrophoretic studies,Myriosclerotinia borealis (=Sclerotinia borealis) is shown to occur on cultivated non-gramineous plants includingIris ensata var.hortensis (Japanese iris),I. pseudoacorus, I. hollandica (Dutch iris), Perko PVH (a hybrid green manure crop betweenBrassica campestris andB. chinensis), Allium fistulosum, andCampanula portenshlagiana. The fungus did not kill these plants, but produced functional sclerotia, capable of carpogenic germination, on decayed leaves or necrotic lesions of overwintered leaves. The fungus seems to act as a saprophyte colonizing senescent leaves and/or as a weak parasite on plants injured by freezing during winter. In culture, the fungus produces discrete tuberoid sclerotia closely attached to the agar surface; rind differentiation is poor on the under surface of sclerotia. Medullary cells are embedded in a gelatinous matrix showing no distinct intercellular spaces. The ectal excipulum of apothecia produced under artificial conditions is composed of globose cells.Myriosclerotinia borealis is thus shown to be very close toCiborinia on the basis of these sclerotial and apothecial characters.     

Antifungal substances produced by Penicillium oxalicum strain PY-1—potential antibiotics against plant pathogenic fungi

This paper reports the isolation from soil of Penicillium strain PY-1 with strong antagonistic activity against plant pathogenic fungi. On the basis of its morphological characteristics and the sequence of the ITS region, strain PY-1 was identified as P. oxalicum. Strain PY-1 produces antifungal substances that suppress the mycelial growth of Sclerotinia sclerotiorum and many other plant pathogenic fungi tested; the highest antagonistic activity was detected at 72 h when cultured in a 250-ml flask containing 80 ml potato dextrose broth. Compared with carbendazim, the relative activity of the antifungal substances produced by strain PY-1 was approximately 4 μg active ingredient (a.i.) per milliliter. The antifungal substances were extracted with ethyl acetate and further separated by high-performance liquid chromatography (HPLC); at least two active components were discovered. The ability to control plant disease with strain PY-1 was confirmed with S. sclerotiorum, a widespread pathogenic fungus that attacks rapeseed (Brassica napus) and other plants. Spores (10⁶ or 10⁷ ml⁻¹) and filtrate (tenfold diluted or undiluted) of strain PY-1 could significantly suppress infection and/or the extent of infection by S. sclerotiorum of plants at seven-true-leaves stage. The potential of strain PY-1 for identifying new antibiotics to control fungal disease and for biological control of plant disease, for example oilseed rape stem rot, is discussed.     

Polyamine metabolism during sclerotial development of Sclerotinia sclerotiorum

A study on polyamine metabolism and the consequences of polyamine biosynthesis inhibition on the development of Sclerotinia sclerotiorum sclerotia was conducted. Concentrations of the triamine spermidine and the tetramine spermine, as well as ornithine decarboxylase and S-adenosyl-methionine decarboxylase activities, decreased during sclerotia maturation. In turn, the concentration of the diamine putrescine was reduced at early stages of sclerotial development but it increased later on. This increment was not related to de novo biosynthesis, as demonstrated by the continuous decrease in ornithine decarboxylase activity. Alternatively, it could be explained by the release of putrescine from the conjugated polyamine pool. α-Difluoro-methylornithine and cyclohexylamine, which inhibit putrescine and spermidine biosynthesis, respectively, decreased mycelial growth, but did not reduce the number of sclerotia produced in vitro even though they disrupted polyamine metabolism during sclerotial development. It can be concluded that sclerotial development is less dependent on polyamine biosynthesis than mycelial growth, and that the increase of free putrescine is a typical feature of sclerotial development. The relationship between polyamine metabolism and sclerotial development, as well as the potential of polyamine biosynthesis inhibition as a strategy for the control of plant diseases caused by sclerotial fungi are discussed.     

Composition and Nutritional Characteristics of Fungi Consumed by Callimico goeldii in Pando, Bolivia

Though ≥22 species of Primates consume fungi, most do so at low rates, comprising <5% of their feeding time. Goeldi's monkeys (Callimico goeldii), spend up to 29% of their feeding time year-round consuming fungal sporocarps, the fruiting bodies of fungi. We provide comprehensive data on the nutritional characteristics of 4 species of fungi consumed by Callimico goeldii (Ascopolyporus polyporoides, Ascopolyporus polychrous, Auricularia auricula, and Auricularia delicata). The composition of the fungi is similar to that of other fungi: predominantly fiber (66.2–83.0% dry matter) with small amounts of sugar (2.0–5.6% dry matter) and crude fat (0.9–1.6% dry matter). Though the crude protein content is substantial (5.5–13.4% dry matter), much of the nitrogen in the fungi is not likely to be available to Callimico goeldii because it is associated with indigestible food components or is in nonprotein form. The mineral content of the fungi are within the normal range for fungi generally and the calcium-to-phosphorus ratio is low (0.07–0.25). Fungi appear to be a low-quality food resource for Callimico goeldii and may contribute to their relatively large home ranges and low population density compared to other Callitrichinae. Research on the ability of Callimico goeldii to digest fungi is needed to understand fully the nutritional value of fungi to them. We discuss adaptations Callimico goeldii may have for improving their ability to obtain nutrients from fungi and potential ecological correlates of mycophagy.     

In vitro fungitoxicity of the essential oil of Syzygium aromaticum

The in vitro antifungal activity of clove oil was studied against four test fungi namely Alternaria alternata, Fusarium chlamydosporum, Helminthosporum oryzae and Rhizoctonia bataticola by the agar well diffusion method. These test fungi were found to be highly sensitive to clove oil at a concentration of 100 μl/well. The inhibition zone diameter was found to be in the range of 55–65 mm. The toxicity of clove oil on the germination and growth of A. alternata was further examined in liquid medium. Concentration- and time-dependent toxicity was recorded from 0.05 to 20% (v/v) concentration. The minimum fungistatic concentration was found to be 0.05%. Above this concentration, lysis of conidia and inhibition of mycelial growth were detected. Microscopic analysis showed 20–40% lysis of conidia after 72 h of incubation at 5% concentration. However at higher clove oil concentration (10%), up to 20% of conidia were lysed within 24 h of incubation. Similar concentration- and time-dependent toxicity was observed at different concentrations and time intervals. The findings indicated that clove oil possesses fungicidal activity against phytopathogenic fungi. Further study is required to determine whether it could have value in the management of plant infectious diseases. This revised version was published online in July 2006 with corrections to the Cover Date.     

The effect of polyamine biosynthesis inhibition on growth and differentiation of the phytopathogenic fungus Sclerotinia sclerotiorum

We studied the effects of several polyamine biosynthesis inhibitors on growth, differentiation, free polyamine levels and in vivo and in vitro activity of polyamine biosynthesis enzymes in Sclerotinia sclerotiorum. -Difluoromethylornithine (DFMO) and -difluoromethylarginine (DFMA) were potent inhibitors of mycelial growth. The effect of DFMO was due to inhibition of ornithine decarboxylase (ODC). No evidence for the existence of an arginine decarboxylase (ADC) pathway was found. The effect of DFMA was partly due to inhibition of ODC, presumably after its conversion into DFMO by mycelial arginase, as suggested by the high activity of this enzyme detected both in intact mycelium and mycelial extracts. In addition, toxic effects of DFMA on cellular processes other than polyamine metabolism might have occurred. Cyclohexylamine (CHA) slightly inhibited mycelial growth and caused an important decrease of free spermidine associated with a drastic increase of free putrescine concentration. Methylglyoxal bis-[guanyl hydrazone] (MGBG) had no effect on mycelial growth. Excepting MGBG, all the inhibitors strongly decreased sclerotial formation. Results demonstrate that sclerotial development is much more sensitive to polyamine biosynthesis inhibition than mycelial growth. Our results suggest that mycelial growth can be supported either by spermidine or putrescine, while spermidine (or the putrescine/spermidine ratio) is important for sclerotial formation to occur. Ascospore germination was completely insensitive to the inhibitors.     

Generation of white mold disease-resistant sunflower plants expressing human lysozyme gene

Sunflower plants were transformed via co-cultivation of previously bombarded hypocotyl explants with Agrobacterium tumefaciens harboring the plasmid pNGL that contains the human lysozyme gene. The transformed shoots were selected using kanamycin and regenerated plants were analyzed using histochemical β-glucuronidase assay. Southern, Western and Northern blot analyses indicated the transfer, expression and stable integration of the foreign DNA into the sunflower genome. Resistance against the phytopathogenic fungus Sclerotinia sclerotiorum, which causes white mold disease, was confirmed using a phytopathogenic test and microscopic observation of the infection process.     

一株高效拮抗向日葵菌核菌的细菌菌株YC16的筛选及其作用效果研究

[目的]筛选高效拮抗向日葵菌核菌的细菌菌株,为开发防治菌核菌病害、提高向日葵产量的生物菌剂提供菌种资源。[方法]以羧甲基纤维素钠(CMC)、小麦秸秆纤维素为唯一碳源的无机盐培养基,分离高效降解纤维素的细菌菌株;采用纤维素降解菌与菌核菌的平板对峙方法,进一步筛选拮抗菌核菌的菌株;利用16S rDNA序列鉴定菌株、PDYA平板对峙实验检验上述所选拮抗菌株的抑菌谱;采用离体向日葵新鲜叶片、草炭土基质盆栽实验,观察拮抗菌菌株抑制菌核菌生长的能力;温室盆栽和田间试验条件下,研究其防治向日葵菌核菌病害、促进生长和提高产量的效果。[结果]筛选了一株高效抑制菌核菌的细菌YC16,经过16S rDNA序列分析,鉴定为解淀粉芽孢杆菌。YC16菌株能够抑制8种病原真菌生长,包括齐整小核菌、腐皮镰孢菌、尖孢镰刀菌、稻梨孢、辣椒疫霉、镰刀菌、尖镰孢黄瓜专化型和向日葵菌核菌;抑制菌核菌感染叶片,抑制率达到了80.42%;抑制盆栽基质中菌核菌的菌丝生长,基质表面菌丝密度比对照减少了50%以上。盆栽接种YC16的向日葵生物量比对照提高54.9%,田间向日葵接种YC16菌剂对菌核菌引发的盘腐病防治效果达39%-100%,产量提高24.4%-30.2%。[结论]YC16生物菌剂施用于土壤,能够有效防治向日葵的茎腐病和盘腐病,展现了防治向日葵菌核病和提高产量的双重效果,是一株具有良好应用前景的高效菌种资源。     

Effects of different excitation and detection spectral regions on room temperature chlorophyll <Emphasis Type="Italic">a</Emphasis> fluorescence parameters

The effects of different spectral region of excitation and detection of chlorophyll (Chl) a fluorescence at room temperature on the estimation of excitation energy utilization within photosystem (PS) 2 were studied in wild-type barley (Hordeum vulgare L. cv. Bonus) and its Chl b-less mutant chlorina f2 grown under low and high irradiances [100 and 1 000 μmol(photon) m⁻² s⁻¹]. Three measuring spectral regimes were applied using a PAM 101 fluorometer: (1) excitation in the red region (maximum at the wavelength of 649 nm) and detection in the far-red region beyond 710 nm, (2) excitation in the blue region (maximum at the wavelength of 461 nm) and detection beyond 710 nm, and (3) excitation in the blue region and detection in the red region (660– 710 nm). Non-photochemical quenching of maximal (NPQ) and minimal fluorescence (SV₀), determined by detecting Chl a fluorescence beyond 710 nm, were significantly higher for blue excitation as compared to red excitation. We suggest that this results from higher non-radiative dissipation of absorbed excitation energy within light-harvesting complexes of PS2 (LHC2) due to preferential excitation of LHC2 by blue radiation and from the lower contribution of PS1 emission to the detected fluorescence in the case of blue excitation. Detection of Chl a fluorescence originating preferentially from PS2 (i.e. in the range of 660–710 nm) led to pronounced increase of NPQ, SV₀, and the PS2 photochemical efficiencies (F_V/F_M and F_V′/F_M′), indicating considerable underestimation of these parameters using the standard set-up of PAM 101. Hence PS1 contribution to the minimal fluorescence level in the irradiance-adapted state may reach up to about 80 %.     

Superoxide radical is involved in the sclerotial differentiation of filamentous phytopathogenic fungi: identification of a fungal xanthine oxidase

This study shows that the direct indicator of oxidative stress superoxide radical (O·??) is involved in the sclerotial differentiation of the phytopathogenic filamentous fungi Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii, and Sclerotinia minor. The production rate of O·?? and the antioxidant enzyme superoxide dismutase (SOD) levels in the sclerotiogenic fungi were significantly higher and lower, respectively, than those of their non-differentiating counterpart strains, which strongly suggests that the oxidative stress of the sclerotium differentiating fungi is higher than that of the non-differentiating ones. Xanthine oxidase (XO), which was detected for the first time in fungi in general, was localized in the cytoplasmic membrane. The contribution of XO in the overall O·??production was very significant, reaching 30-70% among the strains, especially in the transition developmental stage between the undifferentiated and the differentiated state, suggesting a sclerotium triggering and a phytopathogenic role of XO during plant infection. The additional finding that these fungi secrete extracellular SOD can be related to their protection from the response of plants to produce O·?? at infection sites.     

Characterization of chlorophyll–protein complexes isolated from a Siphonous green alga, Bryopsis corticulans

Six chlorophyll–protein complexes are isolated from thylakoid membranes of Bryopsis corticulans by dodecyl-β-d-maltoside polyacrylamide gel electrophoresis. Unlike that of higher plants, the 77 K fluorescence emission spectrum of the CP1 band, the PSI core complexes of B. corticulans, presents two peaks, one at 675 nm and the other at 715–717 nm. The emission peak at 715–717 nm is slightly higher than that at 675 nm in the CP1 band when excited at 438 or 540 nm. However, the peak at 715 nm is obviously lower than that at 675 nm when excited at 480 nm. The excitation spectra of CP1 demonstrate that the peak at 675 nm is mainly attributed to energy from Chl b while it is the energy from Chl a that plays an important role in exciting the peak at 715–717 nm. Siphonaxanthin is found to contribute to both the 675 nm and 715–717 nm peaks. We propose from the above results that chlorophyll a and siphonaxanthin are mainly responsible for the transfer of energy to the far-red region of PSI while it is Chl b that contributes most of the transfer of energy to the red region of PSI. The analysis of chlorophyll composition and spectral characteristics of LHCP¹ and LHCP³ also indicate that higher content of Chl b and siphonaxanthin, mainly presented in LHCP¹, the trimeric form of LHCII, are evolved by B. corticulans to absorb an appropriate amount of light energy so as to adapt to their natural habitats.     

Microbial conversion and in vitro and in vivo antifungal assessment of bioconverted docosahexaenoic acid (bDHA) used against agricultural plant pathogenic fungi

Microbial modification of polyunsaturated fatty acids can often lead to special changes in their structure and in biological potential. Therefore, the aim of this study was to develop potential antifungal agents through the microbial conversion of docosahexaenoic acid (DHA). Bioconverted oil extract of docosahexaenoic acid (bDHA), obtained from the microbial conversion of docosahexaenoic acid (DHA) by Pseudomonas aeruginosa PR3, was assessed for its in vitro and in vivo antifungal potential. Mycelial growth inhibition of test plant pathogens, such as Botrytis cinerea, Colletotrichum capsici, Fusarium oxysporum, Fusarium solani, Phytophthora capsici, Rhizoctonia solani and Sclerotinia sclerotiorum, was measured in vitro. bDHA (5 μl disc⁻¹) inhibited 55.30–65.90% fungal mycelium radial growth of all the tested plant pathogens. Minimum inhibitory concentrations (MICs) of bDHA against the tested plant pathogens were found in the range of 125–500 μg ml⁻¹. Also, bDHA had a strong detrimental effect on spore germination for all the tested plant pathogens. Further, three plant pathogenic fungi, namely C. capsici, F. oxysporum and P. capsici, were subjected to an in vivo antifungal screening. bDHA at higher concentrations revealed a promising antifungal effect in vivo as compared to the positive control oligochitosan. Furthermore, elaborative study of GC-MS analysis was conducted on bioconverted oil extract of DHA to identify the transformation products present in bDHA. The results of this study indicate that the oil extract of bDHA has potential value of industrial significance to control plant pathogenic fungi.