scholarly journals Differential Colonization of Tomato Roots by Nonpathogenic and Pathogenic Fusarium oxysporum Strains May Influence Fusarium Wilt Control

2001 ◽  
Vol 91 (5) ◽  
pp. 449-456 ◽  
Author(s):  
Jian R. Bao ◽  
George Lazarovits
Keyword(s):  
Fusarium Oxysporum ◽  
Pathogenic Fungus ◽  
Root Surface ◽  
Histochemical Staining ◽  
Gus Activity ◽  
Vascular Bundles ◽  
Interaction Sites ◽  
Inoculation Density ◽  
Tomato Roots ◽  
Cell Layers

Histochemical staining, β-glucuronidase (GUS) activity, or placing roots on agar were methods used to characterize interactions between the pathogenic fungus, Fusarium oxysporum f. sp. lycopersici, and the nonpathogenic biocontrol F. oxysporum strain 70T01 with respect to colonization behaviors, interaction sites, and population densities on tomato roots. Mycelia of strain 70T01, a genetic transformant expressing stable GUS activity, hygromycin B resistance, and effective disease control, were localized in epidermal and cortex cell layers of tomato roots in a discontinuous and uneven pattern. In contrast, mycelia of F. oxysporum f. sp. lycopersici were found in the vascular bundles. Thus, direct interactions between the two fungi likely happen in the root surface cell layers. Colonization density of strain 70T01 was related to the inoculation density but decreased with distance from the inoculation site. Host defense reactions, including increased cell wall thickness or papilla deposits, were adjacent to 70T01 hyphae. Experiments done in soil showed that strain 70T01 densities in roots were highest at inoculation zones and barely detectable for root segments more than 2 cm away from the inoculation sites. F. oxysporum f. sp. lycopersici densities were lowest at 70T01 inoculation zones and highest (>10 times) where strain 70T01 was not directly applied. Newly elongating roots where strain 70T01 did not reach were available for infection by the pathogen. The higher strain 70T01 density was always found when the plants were simultaneously infected by F. oxysporum f. sp. lycopersici, suggesting that F. oxysporum f. sp. lycopersici has as much influence in predisposing the plant to colonization by strain 70T01 as strain 70T01 has on providing disease protection against the pathogen.

scholarly journals Colonization of Tomato Root by Pathogenic and Nonpathogenic Fusarium oxysporum Strains Inoculated Together and Separately into the Soil

2006 ◽  
Vol 72 (2) ◽  
pp. 1523-1531 ◽  
Author(s):  
Chantal Olivain ◽  
Claude Humbert ◽  
Jarmila Nahalkova ◽  
Jamshid Fatehi ◽  
Floriane L'Haridon ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Laser Scanning ◽  
Root Surface ◽  
Laser Scanning Microscopy ◽  
Pathogenic Strain ◽  
Confocal Laser ◽  
Fungal Colonization ◽  
Tomato Root ◽  
Tomato Roots ◽  
Nonpathogenic Strain

ABSTRACT In soil, fungal colonization of plant roots has been traditionally studied by indirect methods such as microbial isolation that do not enable direct observation of infection sites or of interactions between fungal pathogens and their antagonists. Confocal laser scanning microscopy was used to visualize the colonization of tomato roots in heat-treated soil and to observe the interactions between a nonpathogenic strain, Fo47, and a pathogenic strain, Fol8, inoculated onto tomato roots in soil. When inoculated separately, both fungi colonized the entire root surface, with the exception of the apical zone. When both strains were introduced together, they both colonized the root surface and were observed at the same locations. When Fo47 was introduced at a higher concentration than Fol8, it colonized much of the root surface, but hyphae of Fol8 could still be observed at the same location on the root. There was no exclusion of the pathogenic strain by the presence of the nonpathogenic strain. These results are not consistent with the hypothesis that specific infection sites exist on the root for Fusarium oxysporum and instead support the hypothesis that competition occurs for nutrients rather than for infection sites.

scholarly journals Development of specific primers for Fusarium oxysporum causing damping off of Lilium formolongi

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Takeshi Toda ◽  
Shun Hanesaka ◽  
Kuniaki Shishido ◽  
Shin-ichi Fuji ◽  
Hiromitsu Furuya
Keyword(s):  
Fusarium Oxysporum ◽  
Pathogenic Fungus ◽  
Primer Design ◽  
Damping Off ◽  
Specific Primers ◽  
Forma Specialis

AbstractPrimers specific for the hypothetical forma specialis of Fusarium oxysporum were designed to amplify DNA from this pathogenic fungus that infects plants including lilies. The F. oxysporum sequence between the transposal elements han and hop was used for primer design. Three primer pairs designed from this region were confirmed as specific for 24 isolates of F. oxysporum pathogenic to lilies, except for one pathogenic isolates as extraordinary. No amplification was observed from F. oxysporum non-pathogenic to lily, from 12 forma specialis, and 14 fungi and oomycetes concerned with Liliaceae plants. We propose that specific primers designed from this region will be useful to detect isolates of F. oxysporum that are pathogenic to lilies.

scholarly journals Treatment with the Mycoparasite Pythium oligandrum Triggers Induction of Defense-Related Reactions in Tomato Roots When Challenged with Fusarium oxysporum f. sp. radicis-lycopersici

1997 ◽  
Vol 87 (1) ◽  
pp. 108-122 ◽  
Author(s):  
Nicole Benhamou ◽  
Patrice Rey ◽  
Mohamed Chérif ◽  
John Hockenhull ◽  
Yves Tirilly
Keyword(s):  
Plant Defense ◽  
Fusarium Oxysporum ◽  
Host Cell ◽  
Cell Walls ◽  
Pythium Oligandrum ◽  
Tomato Plants ◽  
Host Cytoplasm ◽  
Defense Reactions ◽  
Tomato Roots ◽  
Root Tissues

The influence exerted by the mycoparasite Pythium oligandrum in triggering plant defense reactions was investigated using an experimental system in which tomato plants were infected with the crown and root rot pathogen Fusarium oxysporum f. sp. radicis-lycopersici. To assess the antagonistic potential of P. oligandrum against F. oxysporum f. sp. radicis-lycopersici, the interaction between the two fungi was studied by scanning and transmission electron microscopy (SEM and TEM, respectively). SEM investigations of the interaction region between the fungi demonstrated that collapse and loss of turgor of F. oxysporum f. sp. radicis-lycopersici hyphae began soon after close contact was established with P. oligandrum. Ultrastructural observations confirmed that intimate contact between hyphae of P. oligandrum and cells of the pathogen resulted in a series of disturbances, including generalized disorganization of the host cytoplasm, retraction of the plasmalemma, and, finally, complete loss of the protoplasm. Cytochemical labeling of chitin with wheat germ agglutinin (WGA)/ovomucoid-gold complex showed that, except in the area of hyphal penetration, the chitin component of the host cell walls was structurally preserved at a time when the host cytoplasm had undergone complete disorganization. Interestingly, the same antagonistic process was observed in planta. The specific labeling patterns obtained with the exoglucanase-gold and WGA-ovomucoid-gold complexes confirmed that P. oligandrum successfully penetrated invading cells of the pathogen without causing substantial cell wall alterations, shown by the intense labeling of chitin. Cytological investigations of samples from P. oligandrum-inoculated tomato roots revealed that the fungus was able to colonize root tissues without inducing extensive cell damage. However, there was a novel finding concerning the structural alteration of the invading hyphae, evidenced by the frequent occurrence of empty fungal shells in root tissues. Pythium ingress in root tissues was associated with host metabolic changes, culminating in the elaboration of structural barriers at sites of potential fungal penetration. Striking differences in the extent of F. oxysporum f. sp. radicis-lycopersici colonization were observed between P. oligandrum-inoculated and control tomato plants. In control roots, the pathogen multiplied abundantly through much of the tissues, whereas in P. oligandrum-colonized roots pathogen growth was restricted to the outermost root tissues. This restricted pattern of pathogen colonization was accompanied by deposition of newly formed barriers beyond the infection sites. These host reactions appeared to be amplified compared to those seen in nonchallenged P. oligandrum-infected plants. Most hyphae of the pathogen that penetrated the epidermis exhibited considerable changes. Wall appositions contained large amounts of callose, in addition to be infiltrated with phenolic compounds. The labeling pattern obtained with gold-complexed laccase showed that phenolics were widely distributed in Fusarium-challenged P. oligandrum-inoculated tomato roots. Such compounds accumulated in the host cell walls and intercellular spaces. The wall-bound chitin component in Fusarium hyphae colonizing P. oligandrum-inoculated roots was preserved at a time when hyphae had undergone substantial degradation. These observations provide the first convincing evidence that P. oligandrum has the potential to induce plant defense reactions in addition to acting as a mycoparasite.

scholarly journals UJI DAYAHAMBAT EUGENOL DARI DAUN CENGKEH HASIL FRAKSINASI TERHADAP PERTUMBUHAN JAMUR PATOGEN Fusarium oxysporum f.sp. Cubense Eugenol Inhibitory Test From Clove Leaf Fractionation Of Fungal Patogen Growth Fusarium oxysporum f.sp. cubense

AgriPeat ◽  
2019 ◽  
Vol 20 (02) ◽  
pp. 107-113
Author(s):  
Admin Journal
Keyword(s):  
Fusarium Oxysporum ◽  
Vacuum Distillation ◽  
Pathogenic Fungus ◽  
Lethal Concentration ◽  
In Vitro Tests ◽  
In Vitro Test ◽  
Microsoft Excel ◽  
Vitro Test

ABSTRACTThis study aims to determine the inhibition of eugenol derived from fractionation clove leaf essentialoils (CLEO) on the growth of pathogenic fungus Fusarium oxysporum f. sp. cubense (Foc) and LC50(Lethal Concentration 50). This research was in vitro, started with purification of clove leaf essentialoil, fractionation by vacuum distillation and bioassay. In vitro tests include exploration of minimuminhibition and preventability tests. Data were analyzed with Microsoft Excel 2010 program. Theresults of minimum inhibition showed at 218,75 ppm concentration of each level was able to inhibitthe growth of Foc fungi. The minimum inhibition exploration was carried out at 218,75 ppm, 109,38ppm, 54,69 ppm and 27,34 ppm. Exploration results showed that fractionated CLEO has been able toinhibit the growth of Foc fungi at 27,34 ppm in the amount of 15,60%. This concentration is used asthe lowest concentration in the inhibitory test. Furthermore, the inhibitory test was carried out startingat the highest concentration of 218,75 ppm, 109,38 ppm, 54,69 ppm and 27,34 ppm. Observationswere made for 7 days after inoculation (DAI). The results showed the best inhibition was at aconcentration of 218,75 ppm at 90,70% and LC50 at 11.17 µL.Keywords: CLEO, fractionation, Foc, in vitro test and LC50

scholarly journals The sss Colonization Gene of the Tomato-Fusarium oxysporum f. sp. radicis-lycopersici Biocontrol Strain Pseudomonas fluorescens WCS365 Can Improve Root Colonization of Other Wild-type Pseudomonas spp. Bacteria

2000 ◽  
Vol 13 (11) ◽  
pp. 1177-1183 ◽  
Author(s):  
Linda C. Dekkers ◽  
Ine H. M. Mulders ◽  
Claartje C. Phoelich ◽  
Thomas F. C. Chin-A-Woeng ◽  
André H. M. Wijfjes ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Pseudomonas Fluorescens ◽  
Pathogenic Fungus ◽  
Cell Types ◽  
Disease Suppression ◽  
Systemic Resistance ◽  
Root Tip ◽  
Wild Type ◽  
Tomato Root ◽  
Colonization Ability

We show that the disease tomato foot and root rot caused by the pathogenic fungus Fusarium oxysporum f. sp. radicis-lycopersici can be controlled by inoculation of seeds with cells of the efficient root colonizer Pseudomonas fluorescens WCS365, indicating that strain WCS365 is a bio-control strain. The mechanism for disease suppression most likely is induced systemic resistance. P. fluorescens strain WCS365 and P. chlororaphis strain PCL1391, which acts through the production of the antibiotic phenazine-1-carboxamide, were differentially labeled using genes encoding autofluorescent proteins. Inoculation of seeds with a 1:1 mixture of these strains showed that, at the upper part of the root, the two cell types were present as microcolonies of either one or both cell types. Microcolonies at the lower root part were predominantly of one cell type. Mixed inoculation tended to improve biocontrol in comparison with single inoculations. In contrast to what was observed previously for strain PCL1391, mutations in various colonization genes, including sss, did not consistently decrease the biocontrol ability of strain WCS365. Multiple copies of the sss colonization gene in WCS365 improved neither colonization nor biocontrol by this strain. However, introduction of the sss-containing DNA fragment into the poor colonizer P. fluorescens WCS307 and into the good colonizer P. fluorescens F113 increased the competitive tomato root tip colonization ability of the latter strains 16- to 40-fold and 8- to 16-fold, respectively. These results show that improvement of the colonization ability of wild-type Pseudomonas strains by genetic engineering is a realistic goal.

scholarly journals Modes of action of non-pathogenic strains of Fusarium oxysporum in controlling Fusarium wilts

2002 ◽  
Vol 38 (SI 1 - 6th Conf EFPP 2002) ◽  
pp. 195-199 ◽  
Author(s):  
C. Alabouvette ◽  
Ch. Olivain
Keyword(s):  
Fusarium Oxysporum ◽  
Plant Defence ◽  
Root Surface ◽  
Systemic Resistance ◽  
Induce Systemic Resistance ◽  
Biocontrol Efficacy ◽  
Modes Of Action ◽  
Defence Reactions ◽  
Chlamydospore Germination ◽  
Fusarium Wilts

Many studies have demonstrated the capacity of non-pathogenic strains of F. oxysporum to control Fusarium diseases.<br />These non-pathogenic strains show several modes of action contributing to their biocontrol capacity. They are able to<br />compete for nutrients in the soil, affecting the rate of chlamydospore germination and the saprophytic growth of the<br />pathogen, diminishing the probability for the pathogen to reach the root surface. They are competing with the pathogen<br />at the root surface for colonization of infection sites, and inside the root where they induce plant defence reactions. By<br />triggering the defence reactions, they induce systemic resistance of the plant. Depending on the strain, and on the plant<br />species, these mechanisms are more or less important, leading to a more or less efficient biocontrol efficacy.

Samara development of black maple (Acer saccharum ssp. nigrum) with emphasis on the wing

1991 ◽  
Vol 69 (6) ◽  
pp. 1349-1360 ◽  
Author(s):  
Carol Jacobs Peck ◽  
Nels R. Lersten
Keyword(s):  
Acer Saccharum ◽  
Late Summer ◽  
Vascular Bundles ◽  
Short Fibers ◽  
Ground Tissue ◽  
Dorsal Ridge ◽  
Cell Layers ◽  
Oriented Parallel ◽  
Reticulate Venation ◽  
Lateral Orientation

Black maple (Acer saccharum Marsh, ssp. nigrum (Michx. f.) Desm.) carpels are initiated in late summer and over winter as paired, hood-shaped primordia with a naked megasporangium on each inrolled margin. The biloculate ovary develops from the lower portion of the primordium. The mature pericarp, about 30 cells thick, includes (i) the exocarp: outer epidermis and one to three layers of thick-walled hypodermal cells; (ii) the mesocarp: about 20 cells thick with reticulate venation and an innermost crystalliferous layer; and (iii) the endocarp: five to eight layers of short fibers oriented parallel to the locule surface. The samara wing arises from the dorsal ridge of the carpel primordium. The wing blade is approximately 10 cell layers thick with unifacial anatomy. Vascular bundles from opposite sides of the carpel alternate within the wing, thus xylem and phloem are oriented oppositely in adjacent bundles. The chlorenchymatous ground tissue ranges from compact subepidermal cells to elongated spongy cells, with increasing lateral orientation of cell arms in the mid-lamina. These central cells become sclerified, forming curved, branched fibers that buttress the vascular framework. Wing development and structure suggest early photosynthetic activity, which declines as sclerification and drying progress. Key words: Acer saccharum, anatomy, development, fruit, maple, samara.

Studies of the rooting of cuttings of Hydrangea macrophylla: enzyme changes

1972 ◽  
Vol 50 (2) ◽  
pp. 315-322 ◽  
Author(s):  
J. M. Molnar ◽  
L. J. LaCroix
Keyword(s):  
Enzyme Activity ◽  
Starch Content ◽  
Succinic Dehydrogenase ◽  
Adventitious Root Formation ◽  
Histochemical Staining ◽  
Vascular Bundles ◽  
Hydrangea Macrophylla ◽  
Ray Cells ◽  
Rooting Of Cuttings ◽  
Enzyme Changes

Enzyme changes in root initials of Hydrangea macrophylla during adventitious root formation are described. Extensive changes in enzyme activity were demonstrated by histochemical staining and all enzymes investigated showed increased activity in the tissue responsible for root initiation.The earliest change observed was that of peroxidase in the phloem and xylem ray cells. This was followed by a change in the activity of cytochrome oxidase and succinic dehydrogenase. Alpha-amylase was localized by the substrate film method. The highest amylase activity was demonstrated in the epidermal tissues and vascular bundles. As the root primordia developed, enzyme activity shifted from the vascular bundles to the periphery of the bundles. A positive correlation was found between the starch content and root number of cuttings.

Cell wall reinforcement in watermelon shoot base related to its resistance to Fusarium wilt caused by Fusarium oxysporum f. sp. niveum

2014 ◽  
Vol 153 (2) ◽  
pp. 296-305 ◽  
Author(s):  
T.-H. CHANG ◽  
Y.-H. LIN ◽  
K.-S. CHEN ◽  
J.-W. HUANG ◽  
S.-C. HSIAO ◽  
...  
Keyword(s):  
Cell Wall ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Cell Walls ◽  
Phenylalanine Ammonia Lyase ◽  
Signal Molecules ◽  
Vascular Bundles ◽  
Structural Barriers ◽  
Shoot Base ◽  
Bound Phenolics

SUMMARYFusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum, is one of the limiting factors for watermelon production in Taiwan. In recent research, the phenylalanine ammonia lyase (PAL) gene expressed in the shoot base of the Fusarium wilt resistant line JSB was related to Fusarium wilt resistance. Phenylalanine ammonia lyase is the key regulatory enzyme in the phenylpropanoid metabolic pathway. The downstream products of phenolic compounds are considered to be involved in the complicated plant defence mechanisms. They could act as signal molecules, antimicrobial substances and/or structural barriers. To study the resistant mechanisms of Fusarium wilt, the resistant JSB line was examined for comparison of F. oxysporum-watermelon interactions with the susceptible Grand Baby (GB) cultivar. Unlike infected GB, which was seriously colonized by F. oxysporum in the whole plant, the pathogen was limited below the shoot base of inoculated JSB, suggesting that the shoot base of JSB may contribute to Fusarium resistance. The data indicated that a significant increase in PAL activity was found in shoot bases of the resistant JSB line at 3, 9, 12 and 15 days after inoculation (DAI). Shoot bases of resistant watermelons accumulated higher amounts of soluble and cell wall-bound phenolics at 3–9 DAI; the susceptible GB cultivar, however, only increased the cell wall-bound phenolics in shoot bases at 3 DAI. High lignin deposition in the cell walls of vascular bundles was observed in the shoot bases of JSB but not of GB seedlings at 6 and 9 DAI. In the roots and shoot bases of JSB seedlings at 6 DAI, peroxidase enzyme activity increased significantly. In summary, the results suggest that accumulation of cell wall-bound phenolics and increase of peroxidase activity in shoot bases of JSB seedlings during F. oxysporum inoculation, together with the rapid deposition of lignin in the cell walls of vascular bundles, may have provided structural barriers in resistant JSB line to defend against F. oxysporum invasion.

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