Inhibition of Fungal Growth by Macerated Plant Tissues in a Closed Environment

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 476e-476
Author(s):  
Craig S. Charron ◽  
Catherine O. Chardonnet ◽  
Carl E. Sams

The U.S. Clean Air Act bans the use of methyl bromide after 2001. Consequently, the development of alternative methods for control of soilborne pathogens is imperative. One alternative is to exploit the pesticidal properties of macerated tissues of Brassica spp. This study tested the potential of several Brassica spp. for control of fungal pathogens. Pythium ultimum Trow or Rhizoctonia solani Kühn plugs on potato-dextrose agar on petri dishes were sealed in 500-ml glass jars (at 22 °C) containing macerated leaves (10 g) from one of six Brassica spp. Radial growth was measured 24, 48, and 72 h after inoculation. Indian mustard (B. juncea) was the most suppressive, followed by `Florida Broadleaf' mustard (B. juncea). Volatile compounds in the jars were sampled with a solid-phase microextraction device (SPME) and identified by gas chromatography-mass spectrometry (GC-MS). Allyl isothiocyanate (AITC) comprised over 90% of the total volatiles measured from Indian mustard and `Florida Broadleaf' mustard. Isothiocyanates were detected in jars with all plants except broccoli. (Z)-3-hexenyl acetate was emitted by all plants and was the predominant volatile of `Premium Crop' broccoli (B. oleracea L. var. italica), `Michihili Jade Pagoda' Chinese cabbage (B. pekinensis), `Charmant' cabbage (B. oleracea L. var. capitata), and `Blue Scotch Curled' kale (B. oleracea L. var. viridis). To assess the influence of AITC on radial growth of P. ultimum and R. solani, AITC was added to jars to give headspace concentrations of 0.10, 0.20, and 0.30 mg·L–1 (mass of AITC per volume of headspace). Growth of both fungi was inhibited by 0.10 mg·L–1 AITC. 0.20 mg·L–1 AITC was fungicidal to P. ultimum although the highest AITC level tested (0.30 mg·L–1) did not terminate R. solani growth. These results indicate that residues from some Brassica spp. may be a viable part of a soilborne pest control strategy.

1999 ◽  
Vol 124 (5) ◽  
pp. 462-467 ◽  
Author(s):  
Craig S. Charron ◽  
Carl E. Sams

The U.S. Clean Air Act bans the use of methyl bromide after 2005. Consequently, the development of alternative methods for control of soilborne pathogens is imperative. One alternative is to exploit the pesticidal properties of Brassica L. species. Macerated leaves (10 g) from `Premium Crop' broccoli [B. oleracea L. (Botrytis Group)], `Charmant' cabbage [B. oleracea L. (Capitata Group)], `Michihili Jade Pagoda' Chinese cabbage [B. rapa L. (Pekinensis Group)], `Blue Scotch Curled' kale [B. oleracea L. (Acephala Group)], Indian mustard [B. juncea (L.) Czerniak, unknown cultivar] or `Florida Broadleaf' mustard [B. juncea (L.) Czerniak] were placed in 500-mL glass jars. Petri dishes with either Pythium ultimum Trow or Rhizoctonia solani Kühn plugs on potato-dextrose agar were placed over the jar mouths. Radial growth of both fungi was suppressed most by Indian mustard. Volatiles were collected by solid-phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry. Allyl isothiocyanate (AITC) comprised >90% of the volatiles measured from `Florida Broadleaf' mustard and Indian mustard whereas (Z)-3-hexenyl acetate was the predominant compound emitted by the other species. Isothiocyanates were not detected by SPME from `Premium Crop' broccoli and `Blue Scotch Curled' kale although glucosinolates were found in freeze-dried leaves of all species. When exposed to AITC standard, P. ultimum growth was partially suppressed by 1.1 μmol·L-1 (μmol AITC/headspace volume) and completely suppressed by 2.2 μmol·L-1 R. solani was partially suppressed by 1.1, 2.2, and 3.3 μmol·L-1 AITC. Use of Brassica species for control of fungal pathogens is promising; the presence of AITC in both lines of B. juncea suppressed P. ultimum and R. solani but some Brassicas were inhibitory even when isothiocyanates were not detected.


HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 554F-555 ◽  
Author(s):  
Ryan R.P. Noble ◽  
C.S. Charron ◽  
C.E. Sams

The development of alternative methods for control of soilborne pathogens is imperative since the U.S. Clean Air Act bans the use of methyl bromide after 2005. One possibility is to exploit the pesticidal properties of compounds released by macerated Brassica tissues. In this study, masked chaffer beetle larvae were placed in sealed 473-mL jars with 335 g of soil amended with 1%, 2%, 4%, or 8% (g·g–1) Brassica tissue. The most prevalent volatile toxic compound of Brassica juncea (PI 458934) is allyl isothiocyanate (AITC). AITC production was measured in the jars at 0.25, 4, 8, 24, and 48 h using a solid-phase microextraction device (SPME) and gas chromatography. After 7 days, larvae mortality was determined. Control treatments included untreated soil, soil amended with 8% tomato plant tissue, soil amended with pure AITC, and untreated soil with an atmosphere of ≈20% O2 and 0% CO2 changing over 48 h to 2% O2 and 20% CO2. AITC levels were positively correlated to larvae mortality. The estimated lethal concentration for 50% kill (LC50) was 3.6 μg AITC/L soil atmosphere. AITC levels may be influenced by Brassica mass added, soil bulk density, and environmental factors including temperature and moisture. B. juncea has a high tissue AITC concentration. However, the mass of Brassica tissue required for insecticidal application against Cyclocephala sp. is also high, between 4% and 8% of soil mass. Development and selection of Brassica species that produce higher concentrations of isothiocyanate would increase the effectiveness of Brassica biofumigation as an alternative to methyl bromide for controlling soilborne insects.


2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Mostafa M. El-Sheekh ◽  
Ayman Y. Ahmed ◽  
Amira S. Soliman ◽  
Siham E. Abdel-Ghafour ◽  
Hassan M. Sobhy

Abstract Background In this study, the potential of extracts and powders of green seaweeds, Ulva fasciata, and Enteromorpha flexuosa was evaluated as biocontrol against the pathogenic soil-borne fungi, Macrophomina phaseolina and Fusarium solani, infecting cucumber plants in Egypt. The antifungal activity of the algal extracts was evaluated in vitro against the pathogens mycelial fungal growth using five organic solvents. Results Obtained results indicated that mycelial growth inhibition was noticed with F. solani in all algal extracts tested. In M. phaseolina, all algal extracts did not inhibit the fungal growth but affected microsclerotia formation (the main source of the second infection). In the case of F. solani, the highest reduction (68.6%) was noticed, while the chloroform extract of U. fasciata inhibited the radial growth of F. solani to 2.5 cm when E. flexuosa inhibited the radial growth to 4.3 cm as compared with the control (8.0 cm). The gas chromatography-mass spectrometry and the infrared spectroscopy analyses revealed that iron-monocarbonyl, cyclononasiloxane, and their functional groups, including amine, ether, etc., might play a core role in the anti-fungal activity of the seaweed extracts used. Conclusion This work concluded that the macroalgae species with many unique antifungal properties components had an inhibitory effect against soil-borne cucumber diseases. The antimicrobial activity might be explored in the future in numerous diverse applications in agriculture and plant disease control, revealing their actions to control some plant fungal pathogens.


2002 ◽  
Vol 127 (1) ◽  
pp. 27-31 ◽  
Author(s):  
Stephanie G. Harvey ◽  
Heather N. Hannahan ◽  
Carl E. Sams

Allyl isothiocyanate (AITC) is the predominant isothiocyanate produced by damaged tissues of Indian mustard (Brassica juncea (L) Czerniak). This study investigated Indian mustard and AITC mediated suppression of mycelial growth and sclerotial germination of Sclerotium rolfsii Saccardo, a common soilborne pathogen. Indian mustard (IM) treatments of 0, 0.1, 0.2, 0.6, 1.0, 2.0, 4.1, 5.1, 10.2, 20.4, 40.8, 81.6, and 163.3 g·L-1 (weight of reconstituted mustard per liter of air) were evaluated for suppression of mycelial growth. Treatment effect was evaluated by measuring the radial growth of mycelia. Sclerotia were placed in culture tubes containing 18 g autoclaved soil and covered with an additional 5 g soil. AITC at concentrations of 0, 4.0, 16.0, 64.0, 256.0, 1024.0, or 4096.0 μmol·L-1 was injected into the tubes. Treated sclerotia were removed from tubes and plated on potato dextrose agar to determine viability. Mycelial growth was inhibited with IM treatments (P < 0.01). Inhibiting concentrations (IC) of IM for mycelial growth inhibition of 50% and 90% were 0.7 and 1.0 g·L-1, respectively, with death resulting with >2 g·L-1. Inhibition attributable to AITC alone was lower than that achieved by IM producing equivalent amounts of AITC. Germination of sclerotia was negatively correlated with AITC concentration (r = 0.96; P < 0.01). The IC50 and IC90, of AITC were 249.0 and 528.8 μmol·L-1, respectively, at 42 hours. The lethal concentration for sclerotia was not reached; only suppression occurred at the highest treatment concentrations. Sclerotium rolfsii mycelia were sensitive to the IM volatiles and were suppressed at low concentrations. Sclerotia were more resistant than the mycelia and required higher concentrations of AITC to suppress germination.


2020 ◽  
Vol 6 (4) ◽  
pp. 341
Author(s):  
Nongnat Phoka ◽  
Nakarin Suwannarach ◽  
Saisamorn Lumyong ◽  
Shin-ichi Ito ◽  
Kenji Matsui ◽  
...  

Fungal volatile organic compounds (VOCs) emitted by Trichoderma species interact with a plant host and display multifaceted mechanisms. In this study, we investigated the antifungal activity of VOCs emitted by Trichoderma asperelloides PSU-P1 against fungal pathogens, as well as the ability of VOCs to activate defense responses and to promote plant growth in Arabidopsis thaliana. The strain’s VOCs had remarkable antifungal activity against fungal pathogens, with an inhibition range of 15.92–84.95% in a volatile antifungal bioassay. The VOCs of T. asperelloides PSU-P1 promoted the plant growth of A. thaliana, thereby increasing the fresh weight, root length, and chlorophyll content in the VOC-treated A. thaliana relative to those of the control. High expression levels of the chitinase (CHI) and β-1,3-glucanase (GLU) genes were found in the VOC-treated A. thaliana by quantitative reverse transcription polymerase chain reaction (RT-PCR). The VOC-treated A. thaliana had higher defense-related enzyme (peroxidase (POD)) and cell wall-degrading enzyme (chitinase and β-1,3-glucanase) activity than in the control. The headspace VOCs produced by PSU-P1, trapped with solid phase microextraction, and tentatively identified by gas chromatography–mass spectrometry, included 2-methyl-1-butanol, 2-pentylfuran, acetic acid, and 6-pentyl-2H-pyran-2-one (6-PP). The results suggest that T. asperelloides PSU-P1 emits VOCs responsible for antifungal activity, for promoting plant growth, and for inducing defense responses in A. thaliana.


2021 ◽  
Vol 7 (3) ◽  
pp. 187
Author(s):  
On-Uma Ruangwong ◽  
Prisana Wonglom ◽  
Nakarin Suwannarach ◽  
Jaturong Kumla ◽  
Narit Thaochan ◽  
...  

Soil microorganisms are well studied for their beneficial effects on plant growth and their impact on biocontrol agents. The production of volatile antifungal compounds emitted from soil fungi is considered to be an effective ability that can be applied in biofumigants in the control of plant diseases. A soil fungus, Trichoderma asperelloides TSU1, was isolated from flamingo flower cultivated soil and identified on the basis of the morphology and molecular analysis of the internal transcribed spacer (ITS), rpb2, and tef1-α genes. To test T. asperelloides TSU1-produced volatile organic compounds (VOCs) with antifungal activity, the sealed plate method was used. The VOCs of T. asperelloides TSU1 inhibited the mycelial growth of fungal pathogens that were recently reported as emerging diseases in Thailand, namely, Corynespora cassiicola, Fusarium incarnatum, Neopestalotiopsis clavispora, N. cubana, and Sclerotium rolfsii, with a percentage inhibition range of 38.88–68.33%. Solid-phase microextraction (SPME) was applied to trap VOCs from T. asperelloides TSU1 and tentatively identify them through gas chromatography–mass spectrometry (GC/MS). A total of 17 compounds were detected in the VOCs of T. asperelloides TSU1, and the dominant compounds were identified as fluoro(trinitro)methane (18.192% peak area) and 2-phenylethanol (9.803% peak area). Interestingly, the commercial 2-phenyethanol showed antifungal activity against fungal pathogens that were similar to the VOCs of T. asperelloides TSU1 by bioassay. On the basis of our study’s results, T. asperelloides TSU1 isolated from soil displayed antifungal abilities via the production of VOCs responsible for restricting pathogen growth.


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