Germ Tube Growth Research Articles

Deletion of all three MAP kinase genes results in severe defects in stress responses and pathogenesis in Fusarium graminearum

Mitogen-activated protein kinase (MAPK) cascades are activated by external stimuli and convert signals to cellular changes. Individual MAPKs have been characterized in a number of plant pathogenic fungi for their roles in pathogenesis and responses to biotic or abiotic stresses. However, mutants deleted of all the MAPK genes have not been reported in filamentous fungi. To determine the MAPK-less effects in a fungal pathogen, in this study we generated and characterized mutants deleted of all three MAPK genes in the wheat scab fungus Fusarium graminearum. The Gpmk1 mgv1 Fghog1 triple mutants had severe growth defects and was non-pathogenic. It was defective in infection cushion formation and DON production. Conidiation was reduced in the triple mutant, which often produced elongated conidia with more septa than the wild-type conidia. The triple mutant was blocked in sexual reproduction due to the loss of female fertility. Lack of any MAPKs resulted in an increased sensitivity to various abiotic stress including cell wall, osmotic, oxidative stresses, and phytoalexins, which are likely related to the defects of the triple mutant in environmental adaptation and plant infection. The triple mutant also had increased sensitivity to the biocontrol bacterium Bacillus velezensis and fungus Clonostachys rosea. In co-incubation assays with B. velezensis, the Gpmk1 mgv1 Fghog1 mutant had more severe growth limitation than the wild type and was defective in conidium germination and germ tube growth. In confrontation assays, the triple mutant was defective in defending against mycoparasitic activities of C. rosea and the latter could grow over the mutant but not wild-type F. graminearum. RNA-seq and metabolomics analyses showed that the MAPK triple mutant was altered in the expression of many ATP-binding cassette (ABC) and major facilitator superfamily (MFS) transporter genes and the accumulation of metabolites related to arachidonic acid, linoleic acid, and alpha-linolenic acid metabolisms. Overall, as the first study on mutants deleted of all three MAPKs in fungal pathogens, our results showed that although MAPKs are not essential for growth and asexual reproduction, the Gpmk1 mgv1 Fghog1 triple mutant was blocked in plant infection and sexual reproductions. It also had severe defects in responses to various abiotic stresses and bacterial- or fungal-fungal interactions.

Temperatura ótima e limiares térmicos inferior e superior para a germinação de uredosporos e crescimento do tubo germinativo de Phakopsora pachyrhizi

ABSTRACT In laboratory experiments, the effects of temperatures and exposure times on uredospore germination and germ tube growth of Phakopsora pachyrhizi were measured. The study was conducted in biological oxygen demand (BOD) growth chambers, and the effects of the temperatures (factor ‘a’) 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 31, 32, 33, 34, 35 and 36ºC, combined with the exposure times (factor ‘b’) 3, 6, 12 and 24 hours, were tested in a randomized block design and four replicates. After each exposure time, germination and germ tube length were determined. The experiments were repeated twice and the data underwent regression analysis. The generated equations were used to calculate the lower and upper thermal thresholds and the optimal temperature, which were 6.5ºC, 34.2ºC and 22.3ºC, respectively, for spore germination, and 5.8oC, 34.2oC and 22.2oC, respectively, for germ tube length. The temperature thresholds for spore germination are used to calculate the thermal constant K so that rust occurrence in an area cultivated with soybean can be forecasted based on the accumulated heat.

The effect of nitrogen source and quantity on disease expression of Neonectria ditissima in apple

The effects of nitrogen on the interaction between apple trees and European canker caused by Neonectria ditissima are not well understood. Previous field and laboratory studies have shown that nitrogen affects N. ditissima disease development, germination and germ-tube growth in vitro but the type of nitrogen source has not been examined in vivo. Therefore, the aim of this study was to determine the effects of root-applied nitrogen from different sources on the development of European canker on inoculated potted trees. One-year-old ‘Royal Gala’ trees were planted in a low-nitrogen growth substrate and treated with a range of concentrations of calcium ammonium nitrate (CAN) or other nitrogen sources (Ca(NO3)2, KNO3, (NH4)2SO4, NH4NO3, urea, YaraMila™) at equivalent molar rates of nitrogen as the highest CAN treatment. Treatments were applied during the growing season (Nov to May). The control treatment received no applied nitrogen. Bud and leaf scar wounds were inoculated at leaf fall with N. ditissima conidia. Tree growth and health, disease progression and leaf nitrogen content were monitored. The rate of nitrogen application affected tree diameter and leaf nitrogen content while the nitrogen source mainly affected tree survival, powdery mildew incidence, leaf weights, leaf nitrogen and European canker symptom expression. Trees treated with (NH4)2SO4 had the lowest survival rates and highest leaf nitrogen content. Disease expression was highest with NH4NO3 and lowest with KNO3 applications. The control plants (which received no additional nitrogen), showed the least amount of both growth and disease expression. Applications of CAN, even at the lowest rate (20 g), increased disease susceptibility. Increasing rates of CAN applications did not significantly increase disease incidence. Nitrogen concentration is an important factor in the disease development of European canker of apple. Field evaluation is recommended to further validate these results.

Influence of climatic factors on dry flower, grey and green mould diseases of macadamia flowers in Australia.

Flower blights (grey mould, green mould and dry flower) are important diseases of macadamia. Lack of information on pathogen biology and disease epidemiology in macadamia has hampered control options. Effects of climatic variables including temperature, relative humidity (RH) and vapour pressure deficit (VPD) on the abundance, germination and growth of conidia of four fungal pathogens that cause various flower blights in macadamia were studied. Mycelial growth, sporulation, conidial germination and germ tube growth for five isolates each of Botrytis cinerea, Cladosporium cladosporioides, Pestalotiopsis macadamiae and Neopestalotiopsis macadamiae, at eight temperatures, seven RH and the corresponding VPD regimes were determined in vitro. The optimal climatic range of each of the four pathogens was validated during macadamia flowering periods in the 2019 and 2020seasons by conidia detected and quantified using quantitative PCR. Several growth models were fitted to the data with high significance; predicted optima from these models ranged from 0.9 to 1.1kPa VPD for P. macadamiae and N. macadamiae and <0.6kPa VPD for B. cinerea and C. cladosporioides. This study showed that VPD, as a determinant of the fecundity and growth of the four fungal pathogens, was predictive of flower blight incidence in macadamia. The importance of temperature, RH and, thus, VPD for defining the conditions for infection and flower blight epidemics was established. This information provides a firm basis for the development of prediction tools for flower blights in macadamia.

Fungal Jasmonate as a Novel Morphogenetic Signal for Pathogenesis.

A key question that has remained unanswered is how pathogenic fungi switch from vegetative growth to infection-related morphogenesis during a disease cycle. Here, we identify a fungal oxylipin analogous to the phytohormone jasmonic acid (JA), as the principal regulator of such a developmental switch to isotropic growth and pathogenicity in the rice-blast fungus Magnaporthe oryzae. Using specific inhibitors and mutant analyses, we determined the molecular function of intrinsic jasmonates during M. oryzae pathogenesis. Loss of 12-Oxo-phytodienoic Acid (OPDA) Reductase and/or consequent reduction of jasmonate biosynthesis, prolonged germ tube growth and caused delayed initiation and improper development of infection structures in M. oryzae, reminiscent of phenotypic defects upon impaired cyclic AMP (cAMP) signaling. Chemical- or genetic-complementation completely restored proper vegetative growth and appressoria in opr1Δ. Mass spectrometry-based quantification revealed increased OPDA accumulation and significantly decreased jasmonate levels in opr1Δ. Most interestingly, exogenous jasmonate restored proper appressorium formation in pth11Δ that lacks G protein/cAMP signaling; but failed to do so in the Mitogen-activated protein (MAP) kinase mutants. Epistasis analysis placed jasmonate upstream of the cAMP pathway in rice blast. Mechanistically, intrinsic jasmonate orchestrates timely cessation of the vegetative phase and induces pathogenic development via a complex regulatory interaction with the cAMP-PKA cascade and redox signaling in rice blast.

Potential of far ultraviolet (UV) 222 nm light for management of strawberry fungal pathogens

Recently developed, night-time irradiation provided the breakthrough that made ultraviolet (UV) technology with 254 nm (UV–C) commercially feasible as a sustainable alternative to synthetic fungicides for control of pre and postharvest diseases of fruit crops. To make UV technology more efficient, we explored the effectiveness of far UV (222 nm) produced by a Krypton–Chlorine excimer lamp to kill major fungal pathogens of strawberry such as Botrytis cinerea, Penicillium expansum, and various Colletotrichum species and compared it to the conventional 254 nm UV-C treatment in light and dark. We found that 222 nm far UV was three-to ten-fold more effective than 254 nm UV-C in killing conidia of these pathogens, did not require a dark period for enhancing its efficacy, and had no negative effect on plant photosynthesis, pollen germ tube growth and fruit set at doses required to kill these pathogens. The independence from the light conditions most likely spawns from the mechanism of far UV that targets mainly proteins and not DNA as is the case with 254 nm UV-C. Using 222 nm far UV light would allow treatment application at any time of the day as there is no longer the need for a period of darkness as with 254 nm UV-C irradiation. The greater efficacy of 222 nm far UV light treatment will allow UV applicators to travel at increased speeds and cover greater field area making the UV technology even more useful for protecting plants from fungal pathogens.

Epidemiology of urinary candidiasis and antifungal susceptibility pattern of various Candida species at a rural tertiary health care centre of Puducherry, South India- An observational study

Urinary tract infection (UTI) is a common health problem across the globe. Although majority of them are bacterial in origin, there has been an increasing trend in the incidence of UTI due to the yeast like fungi, . UTI due to are in large proportion noscomially acquired and of growing concern is the development of resistance to the commonly used azole group of drugs for their treatment. Since the resistance is more commonly reported among non- albicans , routine species identification and antifungal susceptibility testing is crucial for successful clinical outcomes. This study was conducted to analyse the distribution and risk factors associated with Urinary candidiasis and also to determine the resistance patterns of different to various antifungal agents using phenotypic methods. : A hospital based observational study was conducted from September 2016 to December 2017 on patients presenting with symptomatic UTI. isolates were speciated using phenotypic methods like germ tube test and growth character on chromagar . Antifungal susceptibility to fluconazole, voriconazole, ketoconazole and amphotericin B were determined using disc diffusion method. All data were anlyzed using EpiData Analysis software version 2.2.2.186. A total of 101 were isolated. The incidence of Urinary candidiasis was more among females (66.4%) than in males (33.6%). People above 50 years (38.6%) were commonly affected followed by people in the age group of 21-30 years (22.7%). The incidence among hospitalized patients was 86.7% and urinary catheterization (43.5%) was the most commonly associated risk factor. The most common isolates were tropicalis (31.6%) followed by albicans (21.7%). The overall resistance patterns among various were 50.5%, 32.7%, 19.9% and 2% for fluconazole, ketoconazole, voriconazole and amphotericin B respectively. Hospitalization and urinary catheterization are the important risk factors for developing urinary candidiasis. The antifungal susceptibility varies among different and hence, identification of to species level along with antifungal susceptibility testing should be practiced as a routine in all clinical mycology laboratories.

Antifungal properties of recombinant Puroindoline B protein against aflatoxigenic Aspergillus flavus

Aspergillus flavus contamination is of great concern to food safety. Our previous studies demonstrated that recombinant Puroindoline B protein (rPINB) has an inhibitory effect on A. flavus mycelium development. However, fungal contamination often begins with spore germination within food shelf life. Here, rPINB was evaluated for its antifungal properties against A. flavus spores in vivo and in vitro. The results showed that rPINB could inhibit spore formation and aflatoxin B1 of A. flavus on maize. In vitro analysis revealed its dose-dependent antifungal effect on spore germination and germ tube growth of A. flavus. Scanning electron microscopy revealed that rPINB exposure altered spore morphology, indicating it damaged the cell wall. Transmission electron microscopy and the inhibition of ergosterol synthesis further revealed that rPINB exposure significantly damaged the cell membrane. The mitochondrial membrane potential decreased, and DNA fragments were scattered in the cytoplasm as detected using 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolocarbocyanine iodide and 4′,6-diamidino-2-phenylindole staining. The direct antifungal activity of rPINB observed both in vivo and in vitro suggests that rPINB may be used to prevent fungal contamination of stored foods and agricultural products in the future.

Chemotropic Assay for Testing Fungal Response to Strigolactones and Strigolactone-Like Compounds.

Current knowledge on the mechanism of strigolactones (SLs) as signaling molecules during specific interactions in the rhizosphere is mainly related to the control of germination of parasitic weed seeds and hyphal branching of arbuscular mycorrhizal fungi. Thus, the role of plant secreted SLs in regulating the growth and development of root-colonizing fungi still remains controversial. Fusarium oxysporum can sense and respond to extracellular signals through oriented germ tube emergence and redirectioning of hyphal growth toward gradients of nutrients, sex pheromones, or plant root exudates. However, chemoattractant activity of SLs against microorganisms living in the soil has not been tested so far. Here we propose a quantitative chemotropic assay to understand if and how soil fungi could sense gradients of SLs and SLs-like sources. In the example case of F. oxysporum, hyphae of fungal representative mutants preferentially grow toward the synthetic SL analog GR24; and this chemotropic response requires conserved elements of the fungal invasive growth mitogen-activated protein kinase (MAPK) cascade.

Biocontrol of &amp;lt;i&amp;gt;Mycosphaerella fijiensis&amp;lt;/i&amp;gt; Morelet, the Causal Agent of Black Sigatoka of Banana Tree (&amp;lt;i&amp;gt;Musa&amp;lt;/i&amp;gt; spp.) Using Biopesticides in Côte d’Ivoire

Black Leaf Streak Disease (BLSD) is the most restricting leaf disease to banana tree cultivation around the world. In order to control this disease, synthetic fungicides are extensively used. However, these products pose a real danger to environmental pollution and the health of applicators and consumers. Faced with this situation, alternative solutions must be considered to overcome their systematic use. This study was initiated in this context so as to assess the effectiveness of 20 biopesticide formulations on <i>Mycosphaerella fijiensis</i> conidia stemming from banana tree leaf samples originating from village plantations and showing the typical symptoms of stage 2 or 3 black Sigatoka. The assessment method used was that of dispersion in solid medium. Observations were made under an optical microscope equipped with a camera and consisted in determining the inhibition rates of conidia germ tube growth. A pathogenicity test was performed with 8 <i>Mycosphaerella</i> spp. isolates according to an inoculation technique under controlled conditions on whole plants of 5 banana tree cultivar vivoplants. The assessment of biopesticide protection effectiveness against BLSD was conducted on cultivar "Orishele" (very susceptible) with the most aggressive and virulent strain selected during isolate pathogenicity test. The results obtained show that all biopesticide formulations have significant antifungal activity on <i>M. fijiensis</i> conidia germ tube elongation. The average inhibition rate ranged from 83.31 to 99.89% for all biopesticides. The 8 <i>M. fijiensis</i> isolates used have all raised symptoms characteristic of black leaf streak disease regardless of the cultivar. In contrast, no isolate caused symptoms characteristic of Sigatoka disease (Yellow Sigatoka). Biopesticides and synthetic fungicides significantly reduced disease development rate compared to inoculated and untreated controls, but at varying degrees. Preventive treatment of seedlings is found to be much more effective than curative treatment. However, in order to protect banana and plantain tree varieties against <i>M. fijiensis</i>, both types of treatments are necessary.

Overexpression of the Aspergillus fumigatus Small GTPase, RsrA, Promotes Polarity Establishment during Germination.

Cell polarization comprises highly controlled processes and occurs in most eukaryotic organisms. In yeast, the processes of budding, mating and filamentation require coordinated mechanisms leading to polarized growth. Filamentous fungi, such as Aspergillus fumigatus, are an extreme example of cell polarization, essential for both vegetative and pathogenic growth. A major regulator of polarized growth in yeast is the small GTPase Rsr1, which is essential for bud-site selection. Here, we show that deletion of the putative A. fumigatus ortholog, rsrA, causes only a modest reduction of growth rate and delay in germ tube emergence. In contrast, overexpression of rsrA results in a morphogenesis defect, characterized by a significant delay in polarity establishment followed by the establishment of multiple growth axes. This aberrant phenotype is reversed when rsrA expression levels are decreased, suggesting that correct regulation of RsrA activity is crucial for accurate patterning of polarity establishment. Despite this finding, deletion or overexpression of rsrA resulted in no changes of A. fumigatus virulence attributes in a mouse model of invasive aspergillosis. Additional mutational analyses revealed that RsrA cooperates genetically with the small GTPase, RasA, to support A. fumigatus viability.

Biocontrol ability and action mechanism of dihydromaltophilin against Colletotrichum fructicola causing anthracnose of pear fruit.

Anthracnose caused by Colletotrichum fructicola is one of the most important diseases in pear fruit, resulting in huge economic losses. Public awareness of protecting the environment and food safety, together with pathogen resistance to many key fungicides have led to an urgent need to develop alternative strategies for controlling fruit diseases. Here, the antifungal activity of a natural product, dihydromaltophilin [heat-stable antifungal factor (HSAF)], against C. fructicola in vitro and in vivo was investigated to determine its efficacy for anthracnose management. HSAF exhibited pronounced antifungal activity against in vitro mycelial growth of C. fructicola, with a half-inhibition concentration of 0.43 mg L-1 . Hyphae treated with HSAF showed defects such as hyperbranching, swelling and depolarized growth. Conidia germination in the pathogen was inhibited by HSAF in a dose-dependent manner. In the presence of 4 mg L-1 HSAF, conidia germination was significantly delayed, and germ tube growth was inhibited. HSAF at 8 mg L-1 completely blocked conidia germination in C. fructicola. In addition, HSAF disrupted coordination of cytokinesis with growth and nuclear division, induced reactive oxygen species production in conidia, and damaged the integrity of the conidia cell wall. Moreover, an in vivo test confirmed that 50 mg L-1 HSAF significantly reduced the development of anthracnose decay in pear fruit caused by C. fructicola. HSAF was highly effective in reducing pear anthracnose caused by C. fructicola and has great potential to become a new type of fruit preservative.

Efficacy of epsilon-poly-L-lysine inhibition of postharvest blue mold in apples and potential mechanisms

Penicillium expansum is a major postharvest fungal pathogen and is the causal agent of blue mold decay in apples. Epsilon-poly-l-lysine (ε-PL) is a naturally-occurring polypeptide that has strong antimicrobial activity. It is primarily used to suppress foodborne pathogens in bread, beverage, meat products, etc. The potential application of ε-PL in the management of fungal postharvest diseases of fruit, however, has not been explored. In the present study, the inhibitory effect of ε-PL against blue mold (P. expansum) disease of apples and its potential mechanism of action were investigated. Results indicated that 600 mg L−1 of ε-PL could effectively inhibit mycelial growth of P. expansum in apples. Concentrations of ε-PL > 200 mg L−1 also inhibited germination of conidia and germ tube growth of P. expansum in potato dextrose broth (PDB). The inhibitory effect increased with increasing concentrations of ε-PL concentration. Further studies indicated that the possible mechanisms involved of ε-PL inhibition of P. expansum included the activation of defense-related enzyme activity and gene expression in apple fruit tissues. This included polyphenol oxidase (PPO), catalase (CAT), peroxidase (POD) and phenylalanine ammonialyse (PAL). ε-PL stimulated the production of intracellular reactive oxygen species (ROS) and degraded the integrity of the cell wall and plasma membrane of conidia, resulting in the death of conidial spores of P. expansum or their germination.

Volatile self-inhibitor of spore germination in pathogenic Mucorale Rhizopus arrhizus.

Rhizopus arrhizus is a common pathogenic Mucoralean mold that exists as a saprophyte, and is disseminated through sporangiospores, which germinate to form mycelia under suitable environmental or infection settings. Such morphological transitions are often mediated by self-produced effector molecules in a density-dependent fashion. This study aimed to elucidate if a quorum-dependent, cell-density-driven phenomenon exists in R. arrhizus, and identify the molecule(s) involved. The germination of R. arrhizus was observed to be reliant on the seeding density, with nearly 71% and 47% germination in Sabouraud dextrose and glucose asparagine media respectively at 1× 105-1× 106 spores/mL, and only 10% and 1% germination respectively with 1× 108 spores/mL. The late-growth-stage supernatant also hindered the spore germination and liquid-culture biomass in a dose-dependent way. These effects were being mediated by a volatile inhibitor present in the headspace and supernatant of R. arrhizus cultures, identified as 2-methyl-2-butene by gas chromatography and electron ionization-quadrupole mass spectrometry. The compound was present in a density-dependent manner and considerably impaired fungal germ-tube emergence and elongation during germination. Spore swelling remained unaffected. Multiple thin protrusions comprising of F-actin and microtubules were seen emanating from the treated cells, suggestive of filopodia-like and cytoneme-like extensions. The same compound was also detected in Rhizomucor pusillus.

Genome-wide mRNA and miRNA analysis in the early stages of germ tube outgrowth in Coprinopsis cinerea

Coprinopsis cinerea is a model mushroom-forming basidiomycete which produces basidiospores during sexual reproduction. This fungus is widely used to study fruiting body formation and development. Molecular mechanisms controlling its growth from vegetative mycelium to multicellular mature fruiting body have been studied extensively. However, little is known about the underlying biological processes during germ tube outgrowth or the transition from basidiospores to multinucleate hyphae. To better understand sexual spore germination in fungi, here we examined the time-dependent cellular events at resting, germinating and fully germinated basidiospores of C. cinerea by genome-wide transcriptional and post-transcriptional analyses and by carbohydrate composition analysis. Our results revealed a high demand of protein degradation, and biosynthesis of various compounds at the early stage of basidiospore gemination and dynamic changes of carbohydrate metabolism throughout the germination process. Seven microRNA-like RNAs (milRNAs) were identified in the resting basidiospores of C. cinerea, six of which were basidiospore-specific. Glycogen and trehalose were shown to be the carbon sources supporting the initiation of germ tube outgrowth. One basidiospore-specific milRNA, cci-milR-37, was found to be a potential regulator of glycogen metabolic pathways related to vegetative hyphal growth. Our results demonstrated the mRNA and miRNA-mediated regulation on energy production, protein and carbohydrate metabolisms at the early developmental stages of germ tube to form totipotent hyphae. To our knowledge, this is the first study to show the roles of miRNAs in mushroom basidiospore germination and out-growth.

Effect of heat shock and potassium sorbate treatments on gray mold and postharvest quality of ‘XuXiang’ kiwifruit

We determined whether heat and chemical treatments could reduce the decay of kiwifruit caused by Botrytis cinerea during postharvest storage. Kiwifruits were treated with 5 g/L (w/v) potassium sorbate (PS), with a 48 °C hot water treatment (HT), and with a combined treatment (HT + PS). Mycelial growth of B. cinerea and the postharvest quality of ‘XuXiang’ kiwifruits were evaluated. HT + PS significantly inhibited mycelial growth, germ tube growth, and spore germination of B. cinerea. This treatment also reduced the incidence of gray mold in kiwifruit postharvest, and enhanced activities of defense-related enzymes in kiwifruit tissues. Compared with the control, all treatments resulted in lower malondialdehyde (MDA) contents and higher total phenolic contents in kiwifruits. HT + PS also increased the activities of chitinase and β-1,3-glucanase and the transcript levels of their encoding genes. HT + PS can improve kiwifruit quality and reduce decay during postharvest storage.

The Role of Root Exudates of Barley Colonized by Pseudomonas fluorescens in Enhancing Root Colonization by Fusarium culmorum.

The aim of this study was to find out why after joint inoculation of the substrate with the phytopathogenic fungus Fusarium culmorum and the antagonistic bacterium Pseudomonas fluorescens the amount of the fungus on the root surface in the beginning of the colonization was greater on the roots colonized by the bacterium than on control roots. This phenomenon is especially interesting because joint inoculation with P. fluorescens was always followed by a considerable decrease in the incidence of Fusarium root rot. In two experiments barley was grown in sterile vermiculite inoculated only with F. culmorum, only with P. fluorescens and jointly with the fungus and the bacterium. In the control, vermiculite was not inoculated with any microorganisms. After the removal from the vermiculite, barley plants were transferred into deionized water for the collection of root exudates. The duration of barley growth in the vermiculite and in the water was different in the two experiments. The exudates were tested for their ability to elicit chemotropism in F. culmorum and influence its growth. We did not observe any chemotropism of F. culmorum towards barley root exudates. However, the exudates of the barley colonized by the bacterium stimulated the growth of fungal germ tubes. Using an ultra-performance liquid chromatography system, we found that experimental conditions influenced the quantitative composition of the exudates. The amount of amino acids in the solution of exudates decreased considerably after a prolonged growth of control barley in water, while the presence of P. fluorescens resulted in a considerably increase of the amount of amino acids in the exudates. The exudates of barley colonized by P. fluorescens contained much more glucose, lactic acid and several amino acids than the exudates of control barley. These components are known to be necessary for the growth of F. culmorum. Their presence in the exudates of barley colonized by P. fluorescens seems to be the reason of a more active colonization by the fungus of barley roots colonized by the bacterium.

Inhibitory effects of Bacillus licheniformis BL06 on Phytophthora capsici in pepper by multiple modes of action

Phytophthora capsici is a pathogenic oomycete that affects pepper cultivation and other commercial products, causing serious economic losses. Here, Bacillus licheniformis strain BL06 effectively reduced pepper Phytophthora blight severity. BL06 suppressed P. capsici mycelium growth by 70% in dual culture tests and induced excessive branching and significant lysis of P. capsici hyphae. The BL06 bacterial culture also inhibited in vitro sporangia development in a dose-dependent manner. Moreover, BL06 inhibited motility and displayed lytic activities against zoospores of P. capsici in a dose- and time-dependent manner. Indeed, the P. capsici infectiousness was reduced in host tissue treated by BL06, which is possibly associated with its ability to inhibit zoospore germination and germ tube growth in host tissues. Collectively, our results demonstrate the utility B. licheniformis BL06 as a potential biocontrol agent for the management of Phytophthora blight of peppers.

Evaluation of antifungal activity of six children's toothpaste on Candida albicans isolated from early childhood caries patients.

Early childhood caries (ECC) is an aggressive, destructive form of dental caries that affects the children younger than 6 years of age. Candida is known to increase the adherence of Streptococcus mutans to the oral biofilm and produce acids that cause tooth demineralization. To evaluate the efficacy of six commercially available children's toothpaste on clinical isolates of Candida albicans obtained from ECC patients. The study population comprised 60 children aged 3-6 years having ECC. Samples were divided into six groups comprising ten children in each group. Samples were collected using sterile cotton swabs, inoculated on Sabouraud dextrose agar, and incubated at 37°C for 24 h. Species identification was done by germ tube test and growth on corn meal agar. After the confirmed growth of C. albicans, the six commercially available children's toothpaste namely Organic Children's Coconut Oil Toothpaste®, Aloe Dent Children's Toothpaste®, Patanjali Dant Kanti Junior Toothpaste®, Colgate Kids Toothpaste®, Pediflor Kids Toothpaste®, and Crest Pro-Health Stages Kids Toothpaste® and distilled water as control group were subjected for antifungal activity of C. albicans. Agar plates were incubated at 37°C for 48 h, and the diameter of the zones of inhibition was measured and recorded. Data were tabulated and statistical analysis was done using Statistical Package for the Social Science (16.0) version. Pediflor kids toothpaste® showed maximum antifungal activity and Aloe Dent children's toothpaste® showed minimum antifungal activity. All brands of children's toothpaste show antifungal activity against Candida albicans.

Assessment of in vitro Antifungal Prospective of Fungicides against Alternaria alternata, A Causal Organism of Potato Brown Spot and Early Blight Disease

Efficacy evaluation of three fungicides was undertaken against phytopathogenic fungi Alternaria alternata. Fungicide copper oxychloride was found to restrict the growth of fungi at 500ppm concentration, whereas at 5000ppm concentration of benomyl and mancozeb growth of fungi was not occurred. At 1000ppm concentration growth of fungi was fifty percent compare to control on PDA medium. At 5000ppm concentration of copper oxychloride and mancozeb spore germination did not occur. In case of both the fungicides at 1000ppm concentration percent germination was found between 56 and 75 percent. Germination percent of spores was always lesser than control in all the treatments. Similarly germ tube growth was not occurred in copper oxychloride and mancozeb treated spores at 5000ppm concentration. Germ tube growth was found always influenced by the treatment of fungicides. Inhibitory effect of fungicides was dose dependent and proportional to the concentration of fungicides. Reduction in growth, spore germination and germ tube elongation increased on increasing the concentration of fungicides.