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Characteristics of plant species used for the Alternaria dauci host range study comprising Apiaceae species (cultivated and wild Daucus species) and cultivated non-Apiaceae species
Source publication
The aggressiveness of Alternaria dauci isolates was investigated in greenhouse conditions. Twenty‐seven isolates were pre‐selected from a large collection to represent high diversity according to geographic or host origins and intergenic spacer (IGS) polymorphism. IGS sequence analysis revealed that isolates were grouped within three different clus...
Context in source publication
Citations
... The infected plant sections such as leaf, fruits or stem was cultured on PDA to allow pathogen's growth and kept at 27 ± 2 °C for 5-7 days. A conidial suspension was prepared, according to Boedo et al. [34]. Using a hemocytometer, the spore concentration was determined and corrected to 10 6 spores/ml. ...
Background
Early blight (EB) of Tomatoes, caused by Alternaria solani, is a serious fungal disease that adversely affects tomato production. Infection is characterized by dark lesions on leaves, stems, and fruits. Several agrochemicals can be used to control infection, these chemicals may disrupt environmental equilibrium. An alternative technology is needed to address this significant fungal threat. This study was designed to control the growth of EB in tomatoes caused by A. solani, using green-fabricated silver nanoparticles (Ag-NPs).
Results
Ag-NPs were synthesized through an environmentally friendly and cost-effective approach using leaf extract of Quercus incana Roxb. (Fagaceae). The physico-chemical characterization of the Ag-NPs was conducted through UV-visible spectroscopy, scanning electron microscopy, X-ray diffraction analysis, and Fourier transform infrared spectrometry. The Ag-NPs produced were round with a mean diameter of 27 nm. The antifungal activity of these Ag-NPs was assessed through in vitro Petri plate and in vitro leaflet assays against A. solani. The green fabricated Ag-NPs exhibited excellent antifungal activity in vitro at a concentration of 100 mg/l against A. solani, inhibiting growth by 98.27 ± 1.58% and 92.79 ± 1.33% during Petri plate and leaflet assays, respectively.
Conclusion
In conclusion, this study suggests the practical application of green-fabricated Ag-NPs from Q. incana leaf extract against A. solani to effectively control EB disease in tomatoes.
... Once the infection covers the entire foliage, it becomes impossible to harvest carrot roots mechanically by their leaves. Also, discolouration, secondary infections, and reduced shelf life due to increased susceptibility to decay and rotting are additional effects induced by this foliar pathogen (Boedo et al., 2012). ...
... This includes integrated pest management like using pathogen-free seeds, a E-mail: simona.chrapaciene@lammc.lt resistant cultivars, crop rotations, fungicide application when needed, and additional adaption of biological agents (Davis, 2004;Gugino et al., 2007;Boedo et al., 2012). ...
... Alternaria dauci has been reported as a causal pathogen of cultivated and wild carrots and it has also been claimed that it can infect wild parsnip, celery, and parsley [12,24]. The suitability of other alternate hosts, such as Ridolfia segetum (corn parsley) and Caucalis tenet (hedge parsley), to be infected by A. dauci below controlled environment conditions was reported [40]. ...
... This test had a specific focus on assessing the activity of particular enzymes in A. dauci that are recognized for their role in breaking down plant cell walls to clarify the fungal pathogen's capacity to infiltrate coriander plant tissues. These enzymes play a crucial role in the breakdown of plant tissues at the infection site, constituting the initial stage of the invasion process [37,40]. ...
... The group of enzymes in this consortium synergistically work to break down plant tissue, making it easier for the pathogen to infect the plant. These lytic enzymes also pose a significant threat to the plant's health [40]. Overall, the pathogen has a combination of enzymes that can lead to severe infection. ...
Coriandrum sativum L. is a globally significant economic herb with medicinal and aromatic properties. While coriander leaf blight disease was previously confined to India and the USA, this study presents new evidence of its outbreak in Africa and the Middle East caused by Alternaria dauci. Infected leaves display irregular chlorotic to dark brown necrotic lesions along their edges, resulting in leaf discoloration, collapse, and eventual death. The disease also impacts inflorescences and seeds, significantly reducing seed quality. Koch’s postulates confirmed the pathogenicity of the fungus through the re-isolation of A. dauci from artificially infected leaves, and its morphology aligns with typical A. dauci features. Notably, this study identified strong lytic activity (cellulase: 23.76 U, xylanase: 12.83 U, pectinase: 51.84 U, amylase: 9.12 U, and proteinase: 5.73 U), suggesting a correlation with pathogenicity. Molecular characterization using ITS (ON171224) and the specific Alt-a-1 gene (OR236142) supports the fungal morphology. This research provides the first comprehensive documentation of the pathological, lytic, and molecular evidence of A. dauci leaf blight disease on coriander. Future investigations should prioritize the development of resistant coriander varieties and sustainable disease management strategies, including the use of advanced molecular techniques for swift and accurate disease diagnosis to protect coriander from the devastating impact of A. dauci.
... The Alternaria dauci P2 (FRA017) strain with medium aggressiveness [26] was cultivated on V8 agar medium in the dark at 22 °C for 10-15 days. After fungal growth, one infected agar plate was punched out with a 5 mm diameter punch, which was deposited on the side of a 5 cm diameter malt/agar Petri dish. ...
Alternaria leaf blight, caused by the fungus Alternaria dauci, is the most damaging foliar disease of carrot. Some carrot genotypes exhibit partial resistance to this pathogen and resistance Quantitative Trait Loci (rQTL) have been identified. Co-localization of metabolic QTL and rQTL identified camphene, α-pinene, α-bisabolene, β-cubebene, caryophyllene, germacrene D and α-humulene as terpenes potentially involved in carrot resistance against ALB. By combining genomic and transcriptomic analyses, we identified, under the co-localization regions, terpene-related genes which are differentially expressed between a resistant and a susceptible carrot genotype. These genes include five terpene synthases and twenty transcription factors. In addition, significant mycelial growth inhibition was observed in the presence of α-humulene and caryophyllene.
... Among biotic factors are some diseases caused by various fungi. [5]. reported a 60% loss of coriander yield by a wilting disease caused by Fusarium oxysporum f. sp. ...
Coriander (Coriandrum sativum L.) is one of the important spice crops of Apiaceae family. Coriander seeds are used as medicine to cure indigestion, dysentery, vomiting as well as cold and like all other green leafy vegetables, its leaves are a rich source of vitamins, minerals and iron. The country's annual production of coriander seeds in the year 2021 was over 822 thousand metric tons cultivated over 2.92 lakh hectares. Alternarial leaf spot of Coriander which is caused by Alternaria alternata is one major disease in the coriander. The Trichoderma viride, Pseudomonas fluorescens, Bacillus subtillis and Garlic extract were tested under field conditions during rabi season 2021 for their efficacy against the disease and growth & yield parameters. Among the treatments the maximum plant height (cm) at 90 DAS was recorded in T2 – Trichoderma viride+ Pseudomonas fluorescens followed by T3 – Pseudomonas fluorescens as compared to untreated check control T0. The maximum number of branches at 45 DAS was recorded in T2 – Trichoderma viride+ Pseudomonas fluorescens followed by T3 – Pseudomonas fluorescens as compared to untreated check control T0. The maximum root length at 90 DAS was recorded in T5– Trichoderma viride+ Bacillus subtillis followed by T2 – Trichoderma viride + Pseudomonas fluorescens as compared to untreated check control T0. The minimum disease intensity (%) at 75 DAS was recorded in T2 – Trichoderma viride+ Pseudomonas fluorescens, followed by T1–Trichoderma viride as compared to untreated check control T0. The maximum yield (q/acre) of onion was recorded T4 –Trichoderma viride +Pseudomonas fluorescens followed by T1 – Trichoderma viride as compared to untreated control T0.
... To induce sporulation, A. solani was cultured in PDA medium for 7 days and incubated at 25 ± 2 °C. Suspensions of conidial were prepared and spore density was counted by a hemocytometer and adjusted to 10 6 spores/ ml. as reported by Boedo et al (2012). ...
Background
The eggplant suffers from many biotic stresses that cause severe damage to crop production. One of the most destructive eggplant pathogens is Alternaria solani , which causes early blight disease. A pot experiment was conducted to evaluate the role of fungal endophytes in protecting eggplant against early blight as well as in improving its growth performance.
Results
Endophytic Aspergillus terreus was isolated from Ocimum basilicum leaves and identified morphologically and genetically. In vitro, crude extract of endophytic A. terreus exhibited promising antifungal activity against A. solani where minimum inhibitory concentration (MIC) was 1.25 mg/ml. Severity of the disease and rate of protection from the disease were recorded. Vegetative growth indices, physiological resistance signs (photosynthetic pigments, carbohydrates, proteins, phenols, proline, malondialdehyde (MDA), antioxidant enzymes), and isozymes were estimated. Alternaria solani caused a highly disease severity (87.5%) and a noticeable decreasing in growth characteristics and photosynthetic pigments except for carotenoids. Also, infection with A. solani caused significant decreases in the contents of carbohydrate and protein by 29.94% and 10.52%, respectively. Infection with A. solani caused enhancement in phenolics (77.21%), free proline (30.56%), malondialdehyde (30.26%), superoxide dismutase (SOD) (125.47%), catalase (CAT) (125.93%), peroxidase (POD) (25.07%) and polyphenol oxidase (PPO) (125.37%) compared to healthy plants. In contrast, the use of A. terreus on infected plants succeeded in recovering eggplants from the disease, as the disease severity was recorded (caused protection by 66.67%). Application of A. terreus either on healthy or infected eggplants showed several responses in number and density of peroxidase (POD) and polyphenol oxidase (PPO) isozymes.
Conclusion
It is necessary for us to address the remarkable improvement in the photosynthetic pigments, protein, carbohydrates, and enzymatic activity compared to infected control, which opens the way for more studies on the use of biocides as safe alternatives against fungal diseases.
... AdPKS10 expression was repressed in ITA002 strain compared to FRA001, FRA017 and AUS001 strains. Interestingly, for the other AdPKS genes studied, the opposite pattern was observed: transcription levels seemed to increase with strain aggressiveness, AUS001 being the less aggressive and ITA002 the more aggressive as reported in 61 . ...
... Fungal material. The same four A. dauci strains and one A. brassicicola strain as in 39 61 . Numerous studies were also conducted on strain FRA001 37,39,61,67 . ...
... The same four A. dauci strains and one A. brassicicola strain as in 39 61 . Numerous studies were also conducted on strain FRA001 37,39,61,67 . Those strains were collected as described in 61,73 Fungal growth conditions for transcriptomic samples. ...
Alternaria dauci is a Dothideomycete fungus, causal agent of carrot leaf blight. As a member of the Alternaria genus, known to produce a lot of secondary metabolite toxins, A. dauci is also supposed to synthetize host specific and non-host specific toxins playing a crucial role in pathogenicity. This study provides the first reviewing of secondary metabolism genetic basis in the Alternaria genus by prediction of 55 different putative core genes. Interestingly, aldaulactone, a phytotoxic benzenediol lactone from A. dauci, was demonstrated as important in pathogenicity and in carrot partial resistance to this fungus. As nothing is known about aldaulactone biosynthesis, bioinformatic analyses on a publicly available A. dauci genome data set that were reassembled, thanks to a transcriptome data set described here, allowed to identify 19 putative secondary metabolism clusters. We exploited phylogeny to pinpoint cluster 8 as a candidate in aldaulactone biosynthesis. This cluster contains AdPKS7 and AdPKS8, homologs with genes encoding a reducing and a non-reducing polyketide synthase. Clusters containing such a pair of PKS genes have been identified in the biosynthesis of resorcylic acid lactones or dihydroxyphenylacetic acid lactones. AdPKS7 and AdPKS8 gene expression patterns correlated with aldaulactone production in different experimental conditions. The present results highly suggest that both genes are responsible for aldaulactone biosynthesis.
... The ingredients for pickled cucumbers (dill, mustard seeds, and onions) can also be infected by Alternaria spp. and could be potential sources of the fungi in cucumbers (Boedo et al., 2012;Meena et al., 2010;Ramjegathesh & Ebenezar, 2012). This study aimed to analyze possible causes for cucumber softening by analyzing the pectolytic enzyme activities and Alternaria spp. ...
Proteolytic enzymes or fungi have long been identified as causing softening of pickled cucumbers. As the softening of cucumbers occurs mainly in the pasteurized state, this study considers the hypothesis that vinegar and the added spices could be responsible for this softening by studying polygalacturonase (endo‐/exo‐PG), pectinesterase (PE), and pectin lyase, as well as Alternaria spp. found in the spices. Because of the high endo‐PG activity found in dill, this spice emerged as a possible factor causing spoilage. Compared to dill, the enzyme activity in mustard seeds is eight times lower, and only low levels of enzymes or Alternaria spp. are present in onions or vinegar. Different harvest times and the associated degree of freshness of dill also played a crucial role regarding the endo‐PG activity of up to 25.11 U/g (30°C, mature and very woody dill in late July) but of less than 9.00 U/g in fresh and soft green dill harvested in late June. A temperature of 80°C, held for 3 min, reduced the enzyme activity to less than 1.0 U/g. A final examination of cucumbers with a fixed quantity of mustard seeds, vinegar, and onions but with different variants of dill showed that the quantity of dill and the other ingredients added to the jars is not a potential factor leading to cucumber softening, which conflicts with the hypothesis of cucumber spoilage by vinegar and spices.
Practical Application
This work provides insights into the activity of various pectolytic enzymes and the load of Alternaria spp. in different ingredients used for pickle production. Based on these data and additional pasteurization experiments, this paper evaluates the influence of dill, onions, mustard seeds, and vinegar on cucumber softening.
... A. dauci isolates have been also recovered from naturally infected celery (Apium graveolens L., Apiaceae) and lettuce (Lactuca sativa L., Asteraceae) leaf spots (Koike et al. 2017). Two A. dauci isolates from France were able to infect and induce mild foliar symptoms in tomatoes under artificial inoculation conditions (Boedo et al. 2012). However, to our knowledge, no information is available about A. dauci isolates infecting members of the Solanaceae family under natural conditions. ...
Aim:
To report the characterization of 120 Alternaria isolates inducing early blight-like foliar lesions in nine species of five Solanaceae genera collected across all macro-geographical Brazilian regions.
Material and results:
Phylogenetic relationships were assessed via analyses of the Alternaria alternata allergenic protein-coding, glyceraldehyde-3-phosphate dehydrogenase, and the calmodulin gene sequences. Most of the tomato isolates were placed into the A. linariae cluster, whereas most of the potato isolates were grouped with A. grandis. Novel host-pathogen interactions were also reported. Seventeen isolates were selected for morphometrical characterization and a subsample of 13 isolates was employed in pathogenicity assays on tomato, potato, eggplant, scarlet eggplant, Capsicum annuum,Datura stramonium,Physalis angulata and Nicotiana tabacum. Eleven isolates were able to induce foliar lesions in tomatoes but none in C. annuum. Potato was susceptible to a subgroup of isolates but displayed a subset of isolate-specific interactions. Morphological traits were in overall agreement with molecular and host range data.
Conclusion:
Alternaria linariae and A. grandis were confirmed as the major causal agents of tomato and potato early blight, respectively. However other Alternaria species are also involved with early blight in solanaceous hosts in Brazil.
Significance and impact of the study:
The diversity and host-specificity patterns of the Alternaria isolates from Solanaceae may have practical implications in establishing effective early blight genetic resistance and cultural management strategies especially for tomato and potato crops.
... For example, A. dauci (J.G. Kühn) J.W. Groves & Skolko, causing leaf blight on carrot (Daucus carota L., Apiaceae), has been shown to infect non-Apiaceae hosts including lettuce [46][47][48]. ...
Romaine lettuce (Lactuca sativa) is an important staple of American agriculture. Unlike many vegetables, romaine lettuce is typically consumed raw. Phylloplane microbes occur naturally on plant leaves; consumption of uncooked leaves includes consumption of phylloplane microbes. Despite this fact, the microbes that naturally occur on produce such as romaine lettuce are for the most part uncharacterized. In this study, we conducted culture-based studies of the fungal ro-maine lettuce phylloplane community from organic and conventionally grown samples. In addi-tion to an enumeration of all such microbes, we define and provide a discussion of the genera that form the “core” romaine lettuce mycobiome, which represent 85.5% of all obtained isolates: Al-ternaria, Aureobasidium, Cladosporium, Filobasidium, Naganishia, Papiliotrema, Rhodotorula, Sampai-ozyma, Sporobolomyces, Symmetrospora and Vishniacozyma. We highlight the need for additional mycological expertise in that 23% of species in these core genera appear to be new to science and resolve some taxonomic issues we encountered during our work with new combinations for Aureobasidium bupleuri and Curvibasidium nothofagi. Finally, our work lays the ground for future studies that seek to understand the effect these communities may have on preventing or facili-tating establishment of exogenous microbes, such as food spoilage microbes and plant or human pathogens.
