THE PRODUCTION OF A PHYTOTOXIC SUBSTANCE BY ALTERNARIA ZINNIAE

1967 ◽  
Vol 45 (11) ◽  
pp. 2087-2090 ◽  
Author(s):  
G. A. White ◽  
A. N. Starratt
Keyword(s):  
Seed Germination ◽  
Pathogenic Fungus ◽  
Leaf Tissue ◽  
Leaf Veins ◽  
Weak Activity ◽  
Phytotoxic Compound ◽  
Phytotoxic Substance

A new phytotoxic compound, zinniol, C15H22O4, was isolated from cultures of the pathogenic fungus Alternaria zinniae. The toxin causes severe shrivelling of plant stems, browning of leaf veins, and chlorosis of surrounding leaf tissue. Zinniol inhibits seed germination and shows weak activity against fungi and bacteria.

scholarly journals Herbicidal Activity of Curvulinic Acid Isolated from Nimbya alternantherae

2012 ◽  
Vol 7 (1) ◽  
pp. 1934578X1200700
Author(s):  
Jun Li ◽  
Yonghao Ye ◽  
Xiaoyang Wang ◽  
Liyao Dong
Keyword(s):  
Acetic Acid ◽  
Seed Germination ◽  
Root Length ◽  
Shoot Length ◽  
Herbicidal Activity ◽  
Phytopathogenic Fungus ◽  
Inhibitory Effects ◽  
Liquid Cultures ◽  
First Time ◽  
Phytotoxic Compound

A phytotoxic compound, identified as 2-(2-acetyl-3,5-dihydroxyphenyl) acetic acid (curvulinic acid), was isolated from liquid cultures of the phytopathogenic fungus Nimbya alternantherae. The activity of curvulinic acid on seed germination and seedling growth of Capsella bursa-pastoris was evaluated. Percentage seed germination of C. bursa-pastoris was decreased with increasing concentrations of curvulinic acid. The compound had stronger inhibitory effects on root length than shoot length. At a concentration of 600 μg·mL−1, curvulinic acid caused 73.5% and 66.7% growth inhibition on roots and shoots with IC50 values of 204.7 and 281.1 μg·mL−1, respectively. The finding of curvulinic acid in N. alternantherae and its herbicidal activity are reported here for the first time.

scholarly journals First Report of Lettuce Chlorotic Leaf Rot Disease Caused by Phytoplasma in China

Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1425-1425 ◽  
Author(s):  
J.-X. Lin ◽  
H.-Q. Mou ◽  
J.-M. Liu ◽  
J. Chen ◽  
C.-H. Ji ◽  
...  
Keyword(s):  
Leaf Tissue ◽  
Pcr Analysis ◽  
Reference Pattern ◽  
First Report ◽  
Group I ◽  
Pattern Similarity ◽  
Leaf Veins ◽  
Chlorotic Leaf ◽  
Rot Disease ◽  
Leaf Rot

Lettuce (Lactuca sativa) as annual or biennial crop is an important vegetable in China. The lettuce variety Feiqiao, which is extensively cultivated in autumn and winter, is grown for its stem and is a characteristic species bred in Yong'an City. Since October 2005, a new disease of lettuce has been observed sporadically in the fields. Initially, chlorotic symptoms, or a faded red color, were observed on the inner leaves of the infected lettuce plants. Then, the inner leaves bleached and appeared pale, while the top leaves became straight and elongated, and stopped growing. Gummosis was observed at the base of young leaves, and the whole plant became stunted and died. The disease was named lettuce chlorotic leaf rot disease. In 2008, there was a disease outbreak in Yong'an City with an incidence of approximately 30%. In 2012, total DNA was extracted from 0.1 g of leaf tissue collected from 20 symptomatic and five asymptomatic lettuce plants using the CTAB method. A PCR analysis was performed using the phytoplasma-specific primer set R16mF2/R16mR1 (1). An approximately 1.4-kb amplicon was obtained from all 20 symptomatic plants, but no corresponding DNA fragment was amplified from the five asymptomatic plants. PCR products were cloned in Escherichia coli DH5α, using the pMD18-T vector (TaKaRa, Japan), and two isolates were sequenced. The two 1,431-bp sequences were identical (GenBank Accession No. KJ668578). A BLAST analysis revealed a 99% identity between lettuce chlorotic leaf rot phytoplasma and mulberry dwarf phytoplasma, a group 16SrI phytoplasma described by Win et al. in 2012 (3). After analyzing with iPhyclassifier, the virtual RFLP pattern derived from the 16S rDNA F2n/R2 fragment was most similar to the reference pattern of the 16Sr group I, subgroup B (NC_005303), with a pattern similarity coefficient of 0.99 (2). Additionally, the leaf veins and roots with symptoms were processed for ultrastructural examinations using transmission electron microscopy. Many typical phytoplasma-like bodies were observed in the sieve elements in the leaf veins and roots, and they were spherical to oval or dumbbell shaped and 200 to 800 nm in diameter. In agreement with these findings, seven strains of phytoplasma from 16SrI-A and 16SrI-B subgroups were reported in association with lettuce plants exhibiting various types of symptoms which were not completely consistent with those observed in China (4). To our knowledge, this is the first report of a phytoplasma associated with lettuce in China. References: (1) R. E. Davis et al. Microbiol. Res. 158:229, 2003. (2) W. Wei et al. Int. J. Syst. Evol. Microbiol. 57:1855, 2006. (3) N. K. K. Win et al. J. Gen. Plant Pathol. 78:264, 2012. (4) J. Zhang et al. Phytopathology 94:842, 2004.

scholarly journals The In Planta-Produced Extracellular Proteins ECP1 and ECP2 of Cladosporium fulvum Are Virulence Factors

1997 ◽  
Vol 10 (6) ◽  
pp. 725-734 ◽  
Author(s):  
Richard Laugé ◽  
Matthieu H. A. J. Joosten ◽  
Guido F. J. M. Van den Ackerveken ◽  
Henk W. J. Van den Broek ◽  
Pierre J. G. M. De Wit
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Pathogenic Fungus ◽  
Leaf Tissue ◽  
Defense Responses ◽  
Gene Replacement ◽  
Extracellular Proteins ◽  
Cladosporium Fulvum ◽  
Wild Type ◽  
In Planta

The two extracellular proteins ECP1 and ECP2 are abundantly secreted by the plant-pathogenic fungus Cladosporium fulvum during colonization of the intercellular space of tomato leaves. We examined the involvement of both proteins in pathogenicity and virulence of this fungus. ECP1-deficient, ECP2-deficient, and ECP1/ECP2- deficient isogenic C. fulvum strains were created by targeted gene replacement. Upon inoculation onto susceptible 6-week-old tomato plants, all three mutants showed reduced virulence. Deficiency in ECP2 resulted in a strain that poorly colonized the leaf tissue and secreted lower amounts of the in planta-produced ECP3, AVR4, and AVR9 proteins than the wild-type strain. The ECP2-deficient strain produced little emerging mycelium and few conidia. Deficiency in ECP1 did not significantly modify colonization of the leaf tissue, but reduced secretion of in planta-produced proteins. The ECP1-deficient strain emerged from stomata of the lower epidermis, but failed to sporulate as abundantly as the wild-type strain. A strain deficient in both ECP1 and ECP2 proteins had a phenotype similar to that of the ECP2-deficient strain. Accumulation of pathogenesis-related proteins and induction of late responses, such as leaf desiccation and abscission, occurred more quickly and more severely in tomato after inoculation with the ECP1-, ECP2-, and ECP1/ECP2-deficient strains than after inoculation with the wild-type strain. Moreover, partial collapse of stomatal guard cells occurred at emergence of the ECP2-deficient strain. These results indicate that the ECP1 and ECP2 proteins play a role in virulence of C. fulvum on tomato and suggest that both are involved in suppression of host defense responses.

scholarly journals Modeling Spatial Characteristics in the Biological Control of Fungi at Leaf Scale: Competitive Substrate Colonization by Botrytis cinerea and the Saprophytic Antagonist Ulocladium atrum

2005 ◽  
Vol 95 (4) ◽  
pp. 439-448 ◽  
Author(s):  
G. J. T. Kessel ◽  
J. Köhl ◽  
J. A. Powell ◽  
R. Rabbinge ◽  
W. van der Werf
Keyword(s):  
Biological Control ◽  
Botrytis Cinerea ◽  
Pathogenic Fungus ◽  
Spatial Dynamics ◽  
Leaf Tissue ◽  
Volterra Equations ◽  
Spatial Expansion ◽  
Grid Cells ◽  
Spatially Explicit Model ◽  
Competitive Substrate

A spatially explicit model describing saprophytic colonization of dead cyclamen leaf tissue by the plant-pathogenic fungus Botrytis cinerea and the saprophytic fungal antagonist Ulocladium atrum was constructed. Both fungi explore the leaf and utilize the resources it provides. Leaf tissue is represented by a two-dimensional grid of square grid cells. Fungal competition within grid cells is modeled using Lotka-Volterra equations. Spatial expansion into neighboring grid cells is assumed proportional to the mycelial density gradient between donor and receptor cell. Established fungal biomass is immobile. Radial growth rates of B. cinerea and U. atrum in dead cyclamen leaf tissue were measured to determine parameters describing the spatial dynamics of the fungi. At temperatures from 5 to 25°C, B. cinerea colonies expanded twice as rapidly as U. atrum colonies. In practical biological control, the slower colonization of space by U. atrum thus needs to be compensated by a sufficiently dense and even distribution of conidia on the leaf. Simulation results confirm the importance of spatial expansion to the outcome of the competitive interaction between B. cinerea and U. atrum at leaf scale. A sensitivity analysis further emphasized the importance of a uniform high density cover of vital U. atrum conidia on target leaves.

Light- and electron-microscopic observations of Cladosporium sp. growing on basidia of Exobasidum camelliae var. gracilis

2007 ◽  
Vol 85 (1) ◽  
pp. 76-82 ◽  
Author(s):  
C.W. Mims ◽  
R.T. Hanlin ◽  
E.A. Richardson
Keyword(s):  
White Layer ◽  
Pathogenic Fungus ◽  
Leaf Tissue ◽  
Infected Leaf ◽  
Electron Microscopic ◽  
Abaxial Side ◽  
Plant Pathogenic Fungus ◽  
The Dead

Basidia of the plant-pathogenic fungus Exobasidium camelliae var. gracilis Shirai became exposed on the abaxial side of an infected leaf of Camellia sasanqua Thunb. following the sloughing of the undersurface of the leaf. Basidia were formed in tremendous numbers in a distinct hymenium that appeared as a white, felt-like layer. Subsequently, colonies of another fungus, Cladosporium sp. appeared, initially as tiny dark dots on this white layer, but quickly increased in size to form larger circular colonies that were olive-brown to dark brown in color. Adjacent colonies sometimes merged to form larger growths with irregular margins that often covered much of the hymenium on the underside of an E. camelliae-infected leaf. The hyphae that made up a young Cladosporium sp. colony were primarily confined to the surface of the E. camelliae hymenium, and we found no evidence that hyphae actually penetrated living basidia. However, E. camelliae basidia overrun by Cladosporium sp. eventually showed signs of necrosis and finally collapsed and died, creating a slightly sunken area in the hymenium. Hyphae of Cladosporium sp. grew throughout the remains of the dead basidia, but did not appear to spread into the leaf tissue above the pseudoparenchymatous layer of hyphae that gave rise to the basidia. Based upon our observations, it is clear that Cladosporium sp. is a necrotrophic mycoparasite. More specifically, it qualifies as a contact necrotrophic, since it kills basidia without first penetrating them with its hyphae.

Dissemination of the conifer seed fungus Caloscyphafulgens by small mammals

1984 ◽  
Vol 14 (1) ◽  
pp. 134-137
Author(s):  
Thomas P. Sullivan ◽  
Jack R. Sutherland ◽  
T. A. D. Woods ◽  
Druscilla S. Sullivan
Keyword(s):  
Seed Germination ◽  
Small Mammals ◽  
Lodgepole Pine ◽  
Pathogenic Fungus ◽  
White Spruce ◽  
Field Studies ◽  
Douglas Fir ◽  
Deer Mice ◽  
Red Squirrels ◽  
Conifer Seed

Field studies showed that the seed-pathogenic fungus Caloscyphafulgens (Pers.) Boudier was present in squirrel caches in 25% of the white spruce, Piceaglauca (Moench) Voss, stands in an area near Prince George, B.C. and in duff in 17 and 8% of the lodgepole pine, Pinuscontorta Dougl., clear-cuts there and at Williams Lake, respectively. In the laboratory, deer mice (Peromyscusmaniculatus Wagner), chipmunks (Eutamiastownsendii Bachman), and Douglas squirrels (Tamiasciurusdouglasii Bachman) consumed C. fulgens infested seeds of Douglas-fir, Pseudotsugamenziesii (Mirb.) Franco, lodgepole pine, and white spruce as readily as noninfested seeds. Squirrels also ate C. fulgens ascocarps and passed intact ascospores, but these were not observed to germinate. Red squirrels, T. hudsonicus Erxleben, moved, and ate seeds from, both infested and noninfested Douglas-fir cones in the field. It is proposed that C. fulgens is disseminated by squirrels, and perhaps other rodents, and that the fungus may preserve seeds in caches thereby ensuring squirrel food supplies between cone crops. Caloscyphafulgens may also prevent seed germination in direct seeding trials.

Metribuzin Absorption, Translocation, and Distribution in Two Potato (Solanum tuberosum) Cultivars

Weed Science ◽  
1985 ◽  
Vol 33 (5) ◽  
pp. 629-634 ◽  
Author(s):  
Stanislaw W. Gawronski ◽  
Lloyd C. Haderlie ◽  
Robert H. Callihan ◽  
Robert B. Dwelle
Keyword(s):  
Solanum Tuberosum ◽  
Leaf Tissue ◽  
Total Radioactivity ◽  
Hydroponic Culture ◽  
Russet Burbank ◽  
Susceptible Cultivar ◽  
Root Absorption ◽  
Leaf Veins

Root absorption of14C-5 (ring)-metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] from hydroponic culture and its subsequent translocation in tolerant (‘Russet Burbank’) and susceptible (‘Chipbelle’) potato (Solanum tuberosumL.) cultivars were measured. Differences in root absorption did not appear to be as important to differential tolerance as did translocation differences. Total available metribuzin absorbed was 6 and 7%, 18 and 29%, and 31 and 45% after 1, 4, and 8 days for Russet Burbank and Chipbelle, respectively. Radioactivity was concentrated in stems, petioles, and leaf veins in the tolerant cultivar, whereas interveinal leaf tissue was the major accumulation site for14C in the susceptible cultivar. Of the total radioactivity in the plants after 8 days, 82 and 87% were in the foliage for the tolerant and the susceptible cultivar, respectively. Translocation was apoplastic. Metribuzin tolerance by Russet Burbank is due in part to restricted translocation to the leaf blades. A model for differential transport between cultivars is proposed.

scholarly journals Isolation and Identification of Some Biocontrol Fungi and Evaluation of Their Efficacy Against Charchol Rot Disease Caused by Macrophomina phaseolina on Mung Bean

2021 ◽  
Vol 39 (3) ◽  
pp. 197-203
Author(s):  
Abdel Nabi Matrood ◽  
◽  
Hala Abdel Jaber Abdulhassan ◽  
Mohamad Imad Khrieba ◽  
Mountaser Adam Mohamad Amin ◽  
...  
Keyword(s):  
Seed Germination ◽  
Disease Severity ◽  
Mung Bean ◽  
Fungal Pathogen ◽  
Pathogenic Fungus ◽  
Germination Rate ◽  
Macrophomina Phaseolina ◽  
Bean Seed ◽  
Charcoal Rot ◽  
Rot Disease

This study aimed to isolate and identify Macrophomina phaseolina fungus which was the causal aget of Charcol rot disease on mung bean (Vigna radita Wilczek L) from Elgadisia Governorate in order to isolate, diagnose, and evaluate efficacy of biological control fungal agents isolalated from the rhizosphere of the host plant. The biocontrol agents T. koningii, C. globosum and A. carbonarius were effective in inhibiting the pathogenic fungus under laboratory and greenhouse conditions. Two isolates of M. phaseolina fungal pathogen were identified in most samples of infected mung bean. Pathogenicity tests showed the ability of M. phaseolina to attack the seeds and cause seed rot. Isolates 1 and 2 of the fungal pathogen reduced the seed germination rate to 71.56 and 63.75%, respectively, compared with 86.66% for the control. The results obtained indicated the presence of a significant difference between the two isolates in inducing seedlings damping-off which reached 40% and 30%, respectively, compared with 0% for the control. The disease severity of isolate 1 reached 75.3% and that of isolate 2 reached 63.6%. The inhibitory effect of the fungal antagonists T. koningii and C. globosum varied. A. carbonarius demonstrated level 3 of inhibition to the pathogenic fungus M. phaseolina, whereas C. globosum and T. koningii demostrated inhibitory levels of 2 and 1, respectively. Results obtained also indicated that treatments with antagonistic fungi T. koningii, C. globosum and A. carbonarius increased the growth parameters of the mung bean plant. The antagonistic fungus C. globosum increased the plant height, root fresh and dry weight and chlorophyll content compared with the control. Furthermore, the results showed that treatment with T. koningii increased the mung bean seed germination rate to 100% and decreased disease severity of mung bean charcoal rot disease to 45.88% as compared to 89.86% severity for the contol. Likewise, the other antagonistic fungi A. carbonarius and C. globosum also increased the mung bean seed germination , and decreased mung bean charcoal rot disease severity. Keywords : Charcoal rot disease, mung bean, Macrophomina phaseolina, T. koningii, C. globosum, A. carbonarius.

Ultrastructure of Plant Leaf Tissue Infected with Mite-Borne Viral-Like Pathogens

1970 ◽  
Vol 28 ◽  
pp. 178-179 ◽  
Author(s):  
O. E. Bradfute ◽  
R. E. Whitmoyer ◽  
L. R. Nault
Keyword(s):  
Triticum Aestivum ◽  
Zea Mays ◽  
Electron Microscope ◽  
Hordeum Vulgare ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Leaf Tissue ◽  
Leaf Ultrastructure ◽  
Double Membrane ◽  
Aceria Tulipae

A pathogen transmitted by the eriophyid mite, Aceria tulipae, infects a number of Gramineae producing symptoms similar to wheat spot mosaic virus (1). An electron microscope study of leaf ultrastructure from systemically infected Zea mays, Hordeum vulgare, and Triticum aestivum showed the presence of ovoid, double membrane bodies (0.1 - 0.2 microns) in the cytoplasm of parenchyma, phloem and epidermis cells (Fig. 1 ).

Use of TEM in Plant Disease Diagnosis: A Xylem-Limited Bacterium Associated with Diseased ‘Toronto’ Creeping Bentgrass

1981 ◽  
Vol 39 ◽  
pp. 414-415
Author(s):  
Karen K. Baker ◽  
David L. Roberts
Keyword(s):  
Osmium Tetroxide ◽  
Plant Disease ◽  
Leaf Tissue ◽  
Infectious Agent ◽  
Creeping Bentgrass ◽  
Disease Diagnosis ◽  
Unknown Etiology ◽  
Agrostis Palustris ◽  
Putting Greens ◽  
Plant Disease Diagnosis

Plant disease diagnosis is most often accomplished by examination of symptoms and observation or isolation of causal organisms. Occasionally, diseases of unknown etiology occur and are difficult or impossible to accurately diagnose by the usual means. In 1980, such a disease was observed on Agrostis palustris Huds. c.v. Toronto (creeping bentgrass) putting greens at the Butler National Golf Course in Oak Brook, IL.The wilting symptoms of the disease and the irregular nature of its spread through affected areas suggested that an infectious agent was involved. However, normal isolation procedures did not yield any organism known to infect turf grass. TEM was employed in order to aid in the possible diagnosis of the disease.Crown, root and leaf tissue of both infected and symptomless plants were fixed in cold 5% glutaraldehyde in 0.1 M phosphate buffer, post-fixed in buffered 1% osmium tetroxide, dehydrated in ethanol and embedded in a 1:1 mixture of Spurrs and epon-araldite epoxy resins.

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