Plant Pathogenic Fungus Fusarium Solani Research Articles

Diversity and Plant Growth-Promoting Ability of Endophytic, Halotolerant Bacteria Associated with Tetragonia tetragonioides (Pall.) Kuntze.

The diversity of salt-tolerant cultivable endophytic bacteria associated with the halophyte New Zealand spinach (Tetragonia tetragonioides (Pall.) Kuntze) was studied, and their plant beneficial properties were evaluated. The bacteria isolated from leaves and roots belonged to Agrobacterium, Stenotrophomonas, Bacillus, Brevibacterium, Pseudomonas, Streptomyces, Pseudarthrobacter, Raoultella, Curtobacterium, and Pantoea. Isolates exhibited plant growth-promoting traits, including the production of a phytohormone (indole 3-acetic-acid), cell wall degrading enzymes, and hydrogen cyanide production. Furthermore, antifungal activity against the plant pathogenic fungi Fusarium solani, F. oxysporum, and Verticillium dahliae was detected. Ten out of twenty bacterial isolates were able to synthesize ACC deaminase, which plays a vital role in decreasing ethylene levels in plants. Regardless of the origin of isolated bacteria, root or leaf tissue, they stimulated plant root and shoot growth under 200 mM NaCl conditions. Our study suggests that halophytes such as New Zealand spinach are a promising source for isolating halotolerant plant-beneficial bacteria, which can be considered as potentially efficient biofertilizers in the bioremediation of salt-affected soils.

Studying of cellular interaction of hairpin-like peptide EcAMP1 from barnyard grass (Echinochloa crusgalli L.) seeds with plant pathogenic fungus Fusarium solani using microscopy techniques.

An interaction of recombinant hairpin-like cationic peptide EcAMP1 with conidia of plant pathogenic fungus Fusarium solani at the cellular level was studied by a combination of microscopic methods. EcAMP1 is from barnyard grass (Echinochloa crusgalli L.), and obtained by heterologous expression in Escherichia coli system. As a result, a direct relationship between hyphal growth inhibition and increasing active peptide concentration, time of incubation and fungal physiological condition has been determined. Dynamics of accumulation and redistribution of the peptide studied on fungal cellular cover and inside the conidia cells has been shown. The dynamics are dependent on time of coupling, as well as, a dissimilarity of EcAMP1 binding with cover of fungal conidia and its stepwise accumulation and diffuse localization in the cytoplasm. Correlation between structural disruption of fungal conidia and the presence of morphological changes has also been found. The correlation was found under the influence of peptide high concentrations at concentrations above 32 μM. The results indicate the presence of a binding of EcAMP1 with the surface of fungal conidia, thus, demonstrating a main specificity for its antifungal action at the cellular level. These results, however, cannot exclude the existence of attendant EcAMP1 action based on its intracellular localization on some specific targets. SCANNING 38:591-598, 2016. © 2016 Wiley Periodicals, Inc.

Assessment of Feather Hydrolysate From Thermophilic Actinomycetes for Soil Amendment and Biological Control Application

Protein-rich hydrolysate from feather waste was obtained using a mixed culture of selected thermophilic actinomycete strains, and was tested for possible application as soil amendment and biological control agent. For this purpose, a 4 months laboratory experiment was carried out using two types of urban soils (Sofia, Bulgaria): native park soil and anthropogenic soil. The effect of the obtained hydrolysate on some soil parameters (pH, some enzyme activities and microbial activity), seed germination and ryegrass growth, and activity against some plant pathogenic fungi was studied. The results demonstrated that soil enrichment with the organic solution in low concentrations exerted a positive effect on soil urease and microbial activity, seed germination and ryegrass growth, and this trend was better expressed in the anthropogenic soils. Feather hydrolysate showed good activity against plant pathogenic fungi Fusarium solani, Fusarium oxysporum, Mucor sp. and Aspergillus niger. Produced antifungal compounds were isolated and partially characterized as amphiphilic peptides. To the best of our knowledge, antifungal peptides produced by Thermoactinomyces sp. have not been reported. Therefore, the feather hydrolysate obtained by means of the mixed culture of Thermoactinomyces strains has potential to be used as alternative organic amendment for restoration of contaminated soils and for accelerating ryegrass growth. It could successfully used also for as biocontrol agent applicable to crop plant soil.

Effects of methyl jasmonate and elicitor on the activation of phenylalanine ammonia-lyase and the accumulation of scopoletin and scopolin in tobacco cell cultures

The effects of methyl jasmonate (MJ) and elicitor on the phenylpropanoid metabolism in tobacco was studied. It was found that suspended cells of tobacco, responded to MJ and elicitor from the plant pathogenic fungus Fusarium solani with differential formation of phenolic compounds. Both MJ and elicitor induced phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) activity to comparable levels. Northern hybridization showed that the increase in PAL activity was preceded by PAL mRNA accumulation. PAL was induced transcriptionally and enzymatically faster in elicitor-treated cells as compared to MJ-treated cells. HPLC of extracts from tobacco cells and their culture filtrate treated with MJ, showed an induction of the syntheses of coumarin-scopoletin and scopolin. This effect was not seen in elicitor-treated or control cell cultures. Scopolin was mainly found within the cell (99%), whereas scopoletin accumulated in the culture filtrate (90%). We conclude that though MJ mimics stress, indicating its possible role in the plant defense metabolism, responses of tobacco cells to MJ and elicitor are distinct.

Replication of double-stranded RNA in mycovirus from the plant pathogenic fungus, Fusarium solani

A mycovirus (named FusoV) from the plant pathogenic fungus Fusarium solani possessed two types of double-stranded (ds) RNA genome, designated Ml and M2. RNA-dependent RNA polymerase activity was detected in FusoV particle fractions. An in vitro RNA polymerase reaction using purified FusoV particles that was supplemented with NTPs revealed the synthesis of single-stranded (ss) RNA species and a subsequent formation of dsRNAs having the same size as Ml and M2. The ssRNA species synthesized in the first stage were proved to be of positive polarity (coding strand) for both M1 and M2 by dot blot hybridization analysis. These results suggest that FusoV genomic dsRNA replicates in a conservative manner.

Replication of double-stranded RNA in mycovirus from the plant pathogenic fungus,Fusarium solani

A mycovirus (named FusoV) from the plant pathogenic fungus Fusarium solani possessed two types of double-stranded (ds) RNA genome, designated Ml and M2. RNA-dependent RNA polymerase activity was detected in FusoV particle fractions. An in vitro RNA polymerase reaction using purified FusoV particles that was supplemented with NTPs revealed the synthesis of single-stranded (ss) RNA species and a subsequent formation of dsRNAs having the same size as Ml and M2. The ssRNA species synthesized in the first stage were proved to be of positive polarity (coding strand) for both M1 and M2 by dot blot hybridization analysis. These results suggest that FusoV genomic dsRNA replicates in a conservative manner.

Cloning and characterization of a chitosanase gene from the plant pathogenic fungus Fusarium solani

The plant pathogenic fungus Fusarium solani f. sp. phaseoli SUF386 secretes a chitosanase in the absence of exogenous chitosan. Based on partial amino acid sequences of the purified chitosanase, two degenerate oligonucleotides were synthesized and used as reverse transcription-mediated PCR (RT-PCR) primers to amplify a 500-bp fragment of corresponding cDNA. The PCR product was used as a probe to isolate the genomic copy of the gene ( csn). F. solani csn has an open reading frame encoding a polypeptide of 304 amino acid residues with a calculated molecular mass of 31,876 Da and containing a putative 19-amino acid residue signal sequence. Comparison between the genomic and cDNA sequences revealed that three introns are present in the coding region. Southern blot analysis results indicated that csn is present as a single copy in the genome of F. solani SUF386. The cDNA fragment corresponding to the mature enzyme was introduced into E. coli using an expression vector driven by the T7 promoter. The resulting E. coli transformant overproduced proteins with chitosanolytic activity.

S-carvone as a natural potato sprout inhibiting, fungistatic and bacteristatic compound

S-Carvone, a common monoterpene found in caraway ( Carum carvi L.), inhibits the sprouting of potatoes very efficiently at continuous low head space concentrations. The length growth of potato sprouts was inhibited within 2 days following exposure to S-carvone. Sprouts were able to convert S-carvone into more reduced compounds. In addition, growth of the plant-pathogenic fungi Fusarium solani and Fusarium sulphureum was found to be inhibited by S-carvone at concentrations between 1 and 3 m M. At sub-inhibitory concentration, both F. solani and F. sulphureum converted S-carvone into more reduced compounds which were shown to be less toxic as compared to S-carvone. Finally, the growth rate of Streptococcus thermophilus, Lactococcus lactis and Escherichia coli decreased at S-carvone concentrations above 1 m M. This decrease correlated with a dissipation of the proton motive force generated in these cells.

Effect of kind and method of fungicidal treatment of bean seed on infections by the VA-mycorrhizal fungus Glomus macrocarpum and by the pathogenic fungus Fusarium solani

To test the effect of seed treatment with fungicides on the development of mycorrhizal fungi, bean seeds were treated with fungicide dry or vehicled in the organic solvents, ethanol or dichloromethane and then planted in soil inoculated with the mycorrhizal fungus Glomus macrocarpum and/or the plant pathogenic fungus Fusarium solani. Measurements were made at 4 day intervals, to evaluate the location and extent of colonization of either Glomus macrocarpum or Fusarium solani in the root system. Most combinations of fungicide-solvent had little effect on the extent of colonization by each fungus individually. However, when both fungi were inoculated together, symptoms of F. solani were seen only in the tips of roots which indicate that the mycorrhizal fungus was able to limit the occurrence of the pathogenic fungus.

Effect of kind and method of fungicidal treatment of bean seed on infections by the VA-mycorrhizal fungus Glomus macrocarpum and by the pathogenic fungus Fusarium solani

To test the effect of seed treatment with fungicides on the development of mycorrhizal fungi, bean seeds were treated with fungicide dry or vehicled in the organic solvents, ethanol or dichloromethane and then planted in soil inoculated with the mycorrhizal fungus Glomus macrocarpum and/or the plant pathogenic fungus Fusarium solani. Measurements were made at 4 day intervals, to assess the presence of mycorrhizae or disease in the roots as well as top dry weight, root fresh weight and root length. Fungicidal seed treatment did not affect the initial occurrence of mycorrhizae, number of spores of G. macrocarpum in the soil or root length. Fresh weights of roots and dry weights of tops were greater in the presence of the mycorrhizal fungus. The onslaught of symptoms by F. solani was significantly retarded by treatment with fungicides plus mycorrhizal fungi or fungicides plus organic solvents.

Molecular transformation of Fusarium solani with an antibiotic resistance marker having no fungal DNA homology

A vector was constructed for transformation of the plant pathogenic fungus Fusarium solani. The promoter 35Sp, from cauliflower mosaic virus, was fused to the bacterial gene APH(3')II, which confers resistance to the aminoglycoside antibiotic G418. Two transformation procedures were developed: one using isolated fungal protoplasts, the other using germinated fungal spores. A transformation frequency of 3.3 G418-resistant colonies were obtained per microgram DNA. Of 14 colonies analyzed, 12 had vector sequences integrated into their high molecular weight DNA, and 2 were untransformed. Integration was sometimes accompanied by rearrangements of both the vector and flanking fungal DNAs. Primer-extension analysis of the mRNA from one transformant revealed two putative transcription initiation sites in the chimeric APH(3')II gene. Both sites differed from the normal initiation site in plants. This vector will be useful in transformation systems in which integration by non-homologous recombination is desired.

Two linear plasmids in mitochondria of Fusarium solani f. sp. cucurbitae

Two linear plasmid-like DNAs designated pFSC1 (9.2 kbp) and pFSC2 (8.3 kbp) were found in an isolate of the plant pathogenic fungus Fusarium solani f. sp. cucurbitae race 1. The plasmids were maternally inherited and copurified with mitochondrial DNA obtained from a mitochondria-enriched cell fraction suggesting that they are located in mitochondria. The plasmids did not share extensive sequence similarity. No homology was detected between either plasmid and the nuclear or mitochondrial genome when cloned plasmids were used as probes in Southern hybridization analyses. The fungus was cured of plasmids by ethidium bromide treatment. Compared to the plasmid-containing isolate, plasmid-cured derivatives had reduced pathogenicity on a susceptible plant host, Cucurbita maxima “Pink Banana.”