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Seed-borne fungi are solemn and deleterious pathogens capable of causing significant losses of quantity and quality losses in maize seeds and seedlings. They infect the crop at all points of the production chain from farms to stores. A yield loss of up to 50% can be encountered. Currently, chemical control of the disease is being implemented, though it is accompanied by several negative effects. This study aimed at identifying seed-borne fungi of maize and effective management options. A deep-freezing blotter method and morphological identification of the fungal species were implemented. The seed-borne fungi detected were Fusarium verticillioides, Aspergillus flavus, Aspergillus niger, Penicillium spp., Rhizopus spp., and Curvularia spp. However, in farmer-saved seeds, fungal incidences were significantly higher (p < 0.01) than in certified seeds. To identify more effective management options, the efficacy of water and ethanol-extracted bio-fungicides from three plant species, namely, neem (Azadirachta indica), ginger (Zingiber officinale), and coffee (Coffea arabica) were evaluated. From in vitro assays, ethanol-extracted bio-fungicides have a 100% inhibitory effect on fungal growth, whilst the inhibitory effects of water-extracted bio-fungicides are 55.88% (Azadirachta indica) and 46.31% (Zingiber officinale), followed by 5.15% (Coffea arabica). For the case of an in vivo assay, maize seeds treated with water-extracted bio-fungicides have higher seed germination and seedling vigor percentages. For germination, seeds treated with water-extracted bio-fungicides have higher percentages (neem and ginger (90%) followed by coffee (72.5%)) than ethanol-extracted bio-fungicides (neem (0%), ginger (2.5%), and coffee (0%)). A similar observation is made for seedling weight. Therefore, the tested water-extracted bio-fungicides can be used in treating seeds before sowing them. Further studies on effective methods of extracting bioactive compounds, and improving their shelf life, are recommended. [ABSTRACT FROM AUTHOR]

Seeds of three important cucurbit species (cucumber, melon and zucchini) were obtained through on-line mail-order providers and tested for selected viruses of biosecurity and agronomic concern. One or more of the targeted viruses were detected in 23 of the 31 seed lots tested. The quarantine pest melon necrotic spot virus was detected by ELISA in melon seeds. Multiple instances of contamination with the quarantine pest cucumber green mottle mosaic virus were also detected, and its presence in seeds of all three plant species was confirmed by inoculation and re-isolation from indicator plants. Cucumber mosaic virus, squash mosaic virus and potyviruses were repeatedly detected, and instances of insect pest and plant trash contamination were also observed. Seeds imported into Australia from some on-line sources have potential to introduce organisms of biosecurity concern. [ABSTRACT FROM AUTHOR]

The objectives of this study were to identify stable and high-yielding genotypes grown in organically managed fields in Latvia and Estonia and to determine their canopy parameters and susceptibility to seed-borne diseases. Field trials with barley (Hordeum vulgare L.) were conducted using 26 varieties and breeding lines including 20 covered and six hulless genotypes at three locations over three growing seasons. Estonian breeding line 4533.4.3.6 yielded significantly above the average (3.99 t ha–1; LSD = 0.230 t ha–1) and showed wide adaptability as indicated by the coefficient of regression (bi = 1.05), relatively small deviation from regression (s2d = 0.04) and one of the lowest value of ecovalence (Wi = 1.41%). There were significant differences between genotypes according to the canopy parameters measured, such as growth type, early vigour, crop ground cover and canopy height. High-yielding barley genotypes were characterized by more planophile growth habit and shorter canopy height, thus providing good ground cover in the early stages of plant growth. Rasa was the only variety found to have no plants infected with loose smut or leaf stripe, in either of the locations. [ABSTRACT FROM AUTHOR]

White clover widely cultivated in China is one of the most important perennial leguminous forages in temperate and subtropical regions. There is a large quantity of white clover seeds imported into China each year for demands of high-quality grass seeds. Seedborne diseases may cause significant economic losses. DNA sequencing technologies allow for the direct estimation of microbial community diversity, avoiding culture-based biases. Therefore, we used 16S rRNA gene sequencing to investigate the bacterial communities in white clover seeds collected from four different countries. The results showed that a total of 484,715 clean reads were obtained for further subsequent analysis. In total, 341, 340, 382, and 297 operational taxonomic units were obtained at 3% distance cutoff in DB, MB, TB, and XB samples, respectively. The richness indexes revealed that TB sample from Argentina had the highest bacterial richness in four samples. Our results demonstrated that Proteobacteria was the dominant phyla in MB, TB, and XB; however, Bacteroidetes was the dominant phyla in DB. The dominant genus of DB was Prevotella (11.9%), while Sphingomonas was the major genus of MB (46.9%), TB (55.08%), and XB (47.2%) samples. These results provide useful information for seedborne diseases and transmission of bacteria from seed to seedling. [ABSTRACT FROM AUTHOR]

Verticillium dahliae Kleb. is a soilbome pathogen causing Verticillium wilt disease on several hosts. The pathogen survival structure (i.e., microsclerotia) can be efficiently spread by different dispersal methods. In the present study, the medium to long dispersal spread of the pathogen through rivers and irrigation canals was investigated. Samples of sediments (n = 29) were gathered from eight Lebanese rivers and three regional irrigation canals, in addition to samples of soil particles and plant residues (n = 14) from irrigation filters in commercial orchards. Specific conventional and real-time nested polymerase chain reaction assays detected the pathogen in six rivers—Al Kabir, Al Bared, Litani, Al Awali, Ostwan, and Litani South—and in all sampled canals—Ostwan, Al Bared, and Litani Canal 900. Stalling DNA quantities ranged from 0.2 pg to 21.318 ng and an inoculum density, determined by a traditional plating method, varied between nondetectable and 0.2 microsclerotia/g. Viable V. dahliae microsclerotia were also found in residues collected from mesh-type irrigation filters of five commercial orchards. This study confirms that water is an important inoculum source of V. dahliae. being involved in the efficient spread of microsclerotia in Lebanese agricultural areas. [ABSTRACT FROM AUTHOR]

Bakanae disease (caused by Fusarium fujikuroi) and rice blast (caused by Magnaporthe oryzae) are two of the most important seedborne pathogens of rice. The detection of both pathogens in rice seed is necessary to maintain high quality standards and avoid production losses. Currently, blotter tests are used followed by morphological identification of the developing pathogens to provide an incidence of infection in seed lots. Two loop-mediated isothermal amplification assays were developed with primers designed to target the elongation factor l-a sequence of F. fujikuroi and the calmodulin sequence of M. oryzae. The specificity, sensitivity, selectivity, repeatability, and reproducibility for each assay was assessed in line with the international validation standard published by the European and Mediterranean Plant Protection Organization (PM7/98). The results showed a limit of detection of I (X) to 999 fg of DNA of F. fujikuroi and 10 to 99 pg of M. oryzae DNA. When combined with a commercial DNA extraction kit, the assays were demonstrated to be effective for use in detection of the pathogens in commercial batches of infected rice seed of different cultivars, giving results equivalent to the blotter method, thus demonstrating the reliability o f the method for the surveillance of F. fujikuroi and M. oryzae in seed-testing laboratories. [ABSTRACT FROM AUTHOR]

Seedborne pathogens and pests limit production in many agricultural systems. Quarantine programs help prevent the introduction of exotic pathogens into a country, but few regulations directly apply to reducing the reintroduction and spread of endemic pathogens. Use of phytosanitary thresholds helps limit the movement of pathogen inoculum through seed, but the costs associated with rejected seed lots can be prohibitive for voluntary implementation of phytosanitary thresholds. In this paper, we outline a framework to optimize thresholds for seedborne pathogens, balancing the cost of rejected seed lots and benefit of reduced inoculum levels. The method requires relatively small amounts of data, and the accuracy and robustness of the analysis improves over time as data accumulate from seed testing. We demonstrate the method first and illustrate it with a case study of seedborne oospores of Peronospora effusa, the causal agent of spinach downy mildew. A seed lot threshold of 0.23 oospores per seed could reduce the overall number of oospores entering the production system by 90% while removing 8% of seed lots destined for distribution. Alternative mitigation strategies may result in lower economic losses to seed producers, but have uncertain efficacy. We discuss future challenges and prospects for implementing this approach. [ABSTRACT FROM AUTHOR]

Seed systems have an important role in the distribution of high-quality seed and improved varieties. The structure of seed networks also helps to determine the epidemiological risk for seedborne disease. We present a new approach for evaluating the epidemiological role of nodes in seed networks, and apply it to a regional potato farmer consortium (Consorcio de Productores de Papa [CONPAPA]) in Ecuador. We surveyed farmers to estimate the structure of networks of farmer seed tuber and ware potato transactions, and farmer information sources about pest and disease management. Then, we simulated pathogen spread through seed transaction networks to identify priority nodes for disease detection. The likelihood of pathogen establishment was weighted based on the quality or quantity of information sources about disease management. CONPAPA staff and facilities, a market, and certain farms are priorities for disease management interventions such as training, monitoring, and variety dissemination. Advice from agrochemical store staff was common but assessed as significantly less reliable. Farmer access to information (reported number and quality of sources) was similar for both genders. However, women had a smaller amount of the market share for seed tubers and ware potato. Understanding seed system networks provides input for scenario analyses to evaluate potential system improvements. [ABSTRACT FROM AUTHOR]

Bacterial fruit blotch (BFB) of watermelon caused by Acidovorax citrulli (Ac) is a seedborne disease. Seed treatment with bacterial disinfectants is considered as an important measure for suppression of Ac infection. This study was performed to detect the antibacterial activity of the cultural filtrate (CF) of the saprophytic fungus Aspergillus niger Y-1 against Ac. The six-day-old CF, citric acid (CA, 4 mmol/L) and oxalic acid (OA, 60 mmol/L) were determined for in vitro antibacterial activity against Ac. CF and OA were determined as seed disinfectants for suppression of seedborne infection by Ac. Results showed that production of CA and OA by A. niger in potato dextrose broth was consistently detected by HPLC. The CF, CA and OA inhibited growth of Ac and their inhibitory effect disappeared when the pH values of the three solutions was adjusted to 7.0. OA was more effective than CA in suppression of Ac . The potting experiment showed that both CF and OA applied on watermelon seeds effectively suppressed BFB incidence on seedlings. The efficacy was comparable to the seed treatment with HCl (1%, v/v). This study suggests that the CF of A. niger and OA can be used as seed disinfectants for elimination of seedborne Ac. [ABSTRACT FROM AUTHOR]

Zucchini yellow mosaic virus (ZYMV) remains one of the most widespread and destructive viruses affecting plants from Cucurbitaceae family in Ukraine as well as in other countries. ZYMV during the early stages of plant development can cause significant losses in yield. In current project the possibility of seed transmission of Ukrainian ZYMV isolates was tested on Cucurbita pepo plants in insect-free greenhouse. The rate was assessed by ELISA and RT-PCR. Only one isolate ZYMV-14P showed seedborne transmission with transmission rate 2,6%. This is the first detected seed-transmitted isolate in Ukraine. Phylogenetic analysis defined ZYMV-14P isolate as member of group A. This isolate was clustered with other known Ukrainian isolates and isolates from Hungary, Czech Republic, Austria and France within subgroup AI. [ABSTRACT FROM AUTHOR]

Twenty-three isolates of the genus Trichoderma were recovered from 63 soil samples collected from East Delta Region. The isolates percentage to number of soil samples/ Trichoderma isolates in respect to location were 37%, 45%, 30%, 10%, 46%, and 17% in Sharkia, Ismailia, Port Said, Suez, North Sinai, and South Sinai Districts, respectively. Six different morphologically Trichoderma isolates were selected. The average linear growth rate of Trichoderma isolates ranged between 41.78 mm/day for Trichoderma isolate G5 PP1 and 53.41mm/day for isolate G4 IF2. Antagonism activity in vitro between legumes seed borne fungi, i.e. Fusarium solani, Macrophomina phaseolina and Rhizoctonia solani, (isolated from faba bean, beans, and peas) and selected Trichoderma isolates were done. Trichoderma isolates G4 IF2, G2 NA and G4 IF2 caused a remarkable reduction in linear growth of F. solani, M. phaseolina and R. solani, respectively. Trichoderma isolates G5 PP1, G3 IQ2 and G5 PP1 recorded highly survival of faba bean seedlings were sown in infested soil with F. solani, M. phaseolina and R. solani, respectively. Trichoderma isolates G4 IF2 and G1 SA1 recorded highly survival beans seedlings in infested soil with F. solani and M. phaseolina, respectively. While, Trichoderma isolates G2 NA, G4 IF2 and G6 SoR1 were similar of highly survival seedling in infested soil with R. solani. Trichoderma isolates G1 SA1, G2 NA, and G3 IQ2 were identical of highly survival of peas seedlings in infested soil with F. solani. Whereas treatment with Trichoderma isolates G2 NA, G4 IF2, G5 PP1, and G6 SoR1 showed, highly survival seedling. Trichoderma isolates G2 NA showed highly survival peas seedlings in infested soil with R. solani. In general, Trichoderma isolates G2 NA and G5 PP1were the most effective, which had the highest survival plants. This study suggested that, all selected isolates of Trichoderma needed a molecular identification and genetically improvement to obtain one isolate used as highly effective biocontrol agent against most legumes seed born fungi. [ABSTRACT FROM AUTHOR]

Wheat seed-borne diseases are among the major constraints reducing crop yield and the quality of seed and grain. In this study we aimed to evaluate the type and prevalence of fungal seed-borne diseases in Tajik wheat seed samples. Particular emphasis was given to common bunt resistance in advanced wheat breeding materials. Furthermore, we aimed to identify options for improving the seed quality. Seed samples collected from two different locations in Tajikistan were tested by conventional seed-health testing methods for presence of seed-borne diseases. Nineteen advanced wheat breeding lines and three varieties collected from the Tajik wheat breeding program were screened using an artificial inoculation test for their response to common bunt. Significant differences were found between the locations and genotypes concerning presence of common bunt and black point. Fourteen fungal species, where most of them are pathogenic for wheat, were identified in the seed samples. Tilletia laevis, T. tritici, Bipolaris sorokiniana, Stemphylium spp., and Drechslera spp. were the major pathogenic fungi observed in collected wheat samples. Common bunt was predominantly represented by T. laevis. No strong resistance was found in the studied Tajik wheat material, although a low percentage of infection was found in one line (SHARK/F4105W2.1), while the material was evaluated for common bunt resistance. In managing seed-borne diseases, breeding of resistant varieties should be given a priority, while cultural practices such as preventing contamination and monitoring seed health status should also be considered, as a last resort the use of chemical seed treatments are advised. [ABSTRACT FROM AUTHOR]

Bacterial leaf Blight of cotton a major seed borne foliar disease that attacks the crop at all growth stages leading to cause severe losses in conducive environment. To find out best source of resistance against pathogen this research was conducted in the field area Department of Plant Pathology, University of Agriculture Faisalabad. Incidence of bacterial blight of cotton was determined on twenty eight varieties/advanced lines sown in field to determine the resistance resource against the disease. Two years data showed that seventeen varieties (BT-Z-33, BT-S-78, BT-786, BT-A-ONE, BT -282, BT-886, BT-3701, BT-SPECIAL, BT-802, Non Bt-FH 901, BT-92, BT-131, BT-905, BT-SUPPER, Non Bt-MNH 496, Non Bt-FH 1000, and BT-121) expressed moderately resistant response with 21-50 % disease incidence (rating 4). Five varieties viz. Non Bt-FH 207, Non BT-N 112, Non BT-FH 942, Non BT-MNH 6070 and Non Bt-FH 941exhibited moderately susceptible response with 51-70% disease incidence under rating 5. Four varieties namely Non BT-N 814, Non Bt-FH 900, Non BT-ANMOL and Non Bt-FH 2015 showed susceptible response with 71-80% disease incidence (rating 6) while Non BT-REDACOLA and Non BT-C 26 expressed highly susceptible response with disease incidence 81-100% rating 7 against bacterial blight disease of cotton. Results indicate that a wide range of resistant resource is present in Pakistan against the disease. The selection of diverse germplasm/resistant varieties through screening is the most efficient, environment friendly and economical management strategy for farmers against this disease. [ABSTRACT FROM AUTHOR]

The present study was conducted to detect seed borne mycoflora associated with seven cultivars of sunflower (Helianthus annuus L.) and five cultivars of Zinnia (Zinnia elegans L.) by using Agar and Blotter paper methods. A total 12 genera of fungi were detected including; Alternaria alternata, Aspergillus flavus, Aspergillus niger, Cladosporium sp., Stemphylium helianthi, Penicillium sp., Fusarium oxysporum, Mucor sp., Fusarium moniliforme, Fusarium solani, Rhizocotonia solani and Rhizopus sp. The detected fungi depleted germination 10-30%, 10-20% and seedling mortality 10-17%, 10-12%. in sunflower and Zinnia respectively. A comparative study was designed to evaluate three fungicides to control seed mycoflora at the rate of of 1.5g/kg, 2.0g/kg, 2.5g/kg, 3.0g/kg, Maximum germination percentage was attained in case of seed dressing with Topsin M-70 followed by Bayton and Dithane M-45 at the rate of 3.0g/kg. [ABSTRACT FROM AUTHOR]

The study focuses on soil and seed borne foliar blight diseases. The study area covered pothohar rain fed region of Punjab containing four districts Jhelum, Rawalpindi, Attock and Chakwal. Epidemiological surveys were conducted to check prevalence and incidence of foliar diseases. Samples were collected from 70 locations. Fungi isolated from soil samples belonged to the genera Fusarium, Aspergillus, Mucor, Penicillium, Curvularia and Rhizopus. Yield attributes were also calculated for yield production under different stresses. The results indicated that overall trend of foliar blight diseases was such that diseases took higher toll in Attock>Chakwal>Jhelum>Rawalpindi. Tan spot mean incidence was 7.15 in Chakwal and 2 in Attock, it was absent in Jhelum and Rawalpindi. Net blotch mean incidence was recorded highest among all diseases with values 1.47, 24.33, 13.66 and 14.55 in Chakwal, Jhelum, Rawalpindi and Attock respectively. Scald mean incidence was 2.5 in Attock only. Disease incidence of Septoria and HLB ranged from 0.8 - 2.10 in four districts. Alternariaand Fusarium were recorded highest in Jhelum and Chakwal respectively. Consequently the measured wheat yield and grains quality was affected in presence of foliar blight diseases. It needs improved agricultural practices and better management to combat diseases for higher yields. [ABSTRACT FROM AUTHOR]

Plant diseases caused by different kinds of microorganisms either carried through air, water or present in soil, seeds or propagative planting materials have adverse impact on agriculture production and economy worldwide. Apart from other crops vegetables are also subjected to several seed borne fungal, bacterial and viral pathogens, which cause substantial yield loss upto 10 percent in Pakistan. This article gives vast information regarding significance and prevalence of various kinds of seed borne mycoflora (Alternaria solani, Fusarium oxysporum, F. solani, Botrytis cineria, A. alternata, Chaetomium globosum, Curvularia lunata, Aspergillus niger, Drechslera specifer and Rhizoctonia solani) particularly associated with seeds of tomato. These mycoflora are causative agents of devastating tomato diseases like early blight, fusarium wilt and foot rots, grey mold, root and fruit rots. A range of conventional and modern techniques employed for seed borne fungal detection and different control strategies including chemical and biological methods opted by researchers have been reviewed in present paper. A variety of factors like availability of susceptible plants, favorable environmental conditions and overhead irrigation are serious constraints for plant disease development. Under these conditions, monitoring of plant health and detection of diseases particularly using seed detection assays to screen infested seed lots before planting provide effective disease management strategy. [ABSTRACT FROM AUTHOR]

Common bean (Phaseolus vulgaris L.) is an important legume with high nutritional value. In Nicaragua, certified healthy seeds of local bean varieties are not available, and seedborne fungi have gained little attention. Here, were surveyed seedborne pathogenic fungi in an important local bean cultivar, ‘INTA Rojo’. Beans grown in the four main production areas in Nicaragua (Boaco, Carazo, Estelí, Matagalpa) for future use as seed stock were sampled from four seed storehouses and six seed lots. A total of 133 fungal strains were isolated from surface-sterilized beans and inoculated to healthy lima beans (Phaseolus lunatus) under controlled conditions. Eighty-seven isolates caused symptoms of varying severity in the seedlings, including discoloration, necrotic lesions, cankers, rot, and lethal necrosis. Pathogenic isolates were divided into eight phenotypically distinguishable groups based on morphology and growth characteristics on artificial growth medium, and further identified by analysis of the internal transcribed spacer sequences (ITS1 and ITS2) of the ribosomal RNA genes. The pathogenic isolates belonged to eight genera. Fusarium spp. (F. chlamydosporum, F. equiseti, F. incarnatum), Lasiodiplodia theobromae, Macrophomina phaseolina, and Penicillium citrinum were the most damaging and common fungi found in the seed lots. Furthermore, Corynespora cassiicola, Colletotrichum capsisi, Colletotrichum gloeosporioides, Aspergillus flavus, and Diaporthe sp. (Phomopsis) were seedborne in cultivar ‘INTA Rojo’ and found to be pathogenic to bean seedlings. This study reveals, for the first time, many seedborne pathogenic fungi in beans in Nicaragua; furthermore, prior to this study, little information was available concerning F. equiseti, F. incarnatum, L. theobromae, C. cassiicola, and Diaporthe spp. as seedborne pathogens of common bean. Our results lay the basis for developing diagnostic tools for seed health inspection and for further study of the epidemiology, ecology, and control of the pathogenic fungi of common beans in the field. [ABSTRACT FROM AUTHOR]

The incidence of seed-borne mycoflora in sahbhagi rice was screened by Agar plate method and Blotter method. Seed stored in different conditions like Bin and Gunny bag then observation was taken periodically 0, 3, 6, 9, 12 months in each storage condition. Surface sterilization was done by 0.1% mercuric chloride (HgCl2) solution. Both surface sterilized and unsterilized seeds were taken for isolation of fungi. A total number of 16 fungal species including Rhizopus stolonifer, Mucor hiemalis, Aspergillus flavus, A. niger, A. candidus, A. fumigates, Penicillium rubrum, P. citrinum, Alternaria alternata, Drecshlera gramini, Curvularia lunata, Trichoderma harzianum, Microdochium lycopodinum, Fusarium oxysporum, Dark Sterile Mycelium and White Sterile Mycelium were found to be associated with the Sahabhagirice cultivar. Among them the most predominant seed-borne fungi, associated with seed were A. niger (56.67% & 63.33%), A. flavus (53.33% & 56.67%), P. citrinum (50% & 53.33%) and M. lycopodinum (50% & 53.33%) by Agar plate method and A. niger (50% & 56.67%), A. flavus (46.67% & 53.33%), P. citrinum (46.67% & 50%) and M. lycopodinum (46.67% & 50%) by Blotter method in Bin and Gunny Bag storage condition, respectively at the end of storage. Visual examination of seed showed that the maximum increase in the number of abnormal seed was recorded in gunny bag than Bin. Highest percent incidence of seed borne fungi was recorded in Gunny bag storage condition than Bin. In both storage procedures control seed yielded more number of seed-borne fungi as compared to sterilized seed during different storage period. [ABSTRACT FROM AUTHOR]

Landraces are heterogeneous populations and their variability goes through continuous alterations because of physical, genetic, and epigenetic procedures exacerbated by the ongoing climatic changes. Appropriate stewardship of landrace diversity is pivotal to promote its longevity in a manner that is sustainable from the farming perspective. A seed multiplication procedure is presented based on the assumption that in order to improve effectiveness in resource use and increase seed productivity, landraces should comprise genotypes which minimize intra-species competition. These aforementioned genotypes should be of the "weak competitor" ideotype, which are selected so as to alleviate the interplant competition and reach as high as possible crop stand uniformity. Stand uniformity is essential to ensure the same growing conditions for each plant. Reduced intra-crop inequality and equal use of inputs by individual plants will optimize crop performance. Precisely, the "weak competitor" is most often of high yield potential due to a negative association between yielding and competitive ability. Therefore, the suggested procedure involves initial reproduction at nil-competition (widely spaced plants to preclude any plant-to-plant interference for inputs) where "off-type" and low yielding plants are omitted, followed by subsequent multiplication at dense stands. This may represent an effective cultural practice to improve also the landrace health status concerning seed-borne diseases in the absence of certification systems. [ABSTRACT FROM AUTHOR]

Five species ofPenicillium(Penicillium chrysogenum, P. funiculosum,P. griseofulvum,P. implicatumandP. oxalicum) are implicated in seed-borne diseases. Here, we report the discovery of molecular markers based on the internal transcribed spacer regions of fungal ribosomal DNA (rDNA), which are described as primary DNA barcode markers of fungi, for rapid diagnosis and early detection ofPenicilliumspp. The present markers are expected to be useful for the prevention of seedling and systemic plant diseases associated withPenicilliumspp. Our findings, which provide valuable insights into the taxonomy ofPenicilliumspp., should contribute to improve safety of agricultural produce, thereby protecting both humans and animals from harmful food contaminants such as mycotoxins. In addition, we examined the cellular fatty acid composition of five species ofPenicillium. The species studied were found to possess similar fatty acid composition; however, they differed in terms of relative concentration. The principal fatty acids were oleic acid (C18:1) and linoleic acid (C18:2), comprising 80% or more of the total fatty acid composition of these species. These fatty acid profiles may be useful for characterization and identification of fungi. Data derived from the present study highlight the importance of using polyphasic methods for accurate species-level identification ofPenicillium. [ABSTRACT FROM PUBLISHER]

The rhizosphere soil samples were collected during crop growth of black gram, green gram and horse gram at Regional Research Station, Paiyur, Tamil Nadu, India for isolation of B. thuringiensis (Bt). Thirty Bt like colonies based on colony morphology viz.,fried egg colonies were identified from soil samples of Black gram, green gram and horse gram. Among the 30 fried egg colonies, eleven Bt colonies viz., five from black gram, four from green gram and two from horse gram soil samples were identified based on crystal protein under microscope. All the 11 colonies were plated on 0.5% colloidal chitin agar (CCA) medium and the results revealed that among the 11 Bt colonies, six Bt colonies produced zone of clearance over 0.3cm . Out of six colonies, BG7 produced 0.8cm clearance of zone on CCA plates followed by BG10 (0.72cm). All the six colonies were further screened by chitinase activity and the results showed that among the six Bt colonies, BG7 produced highest level of (2.4 U/ml) chitinase activity followed by BG10 (1.98 U/ml). The growth conditions for isolate, BG7 which showed maximum chitinase activity were optimized under different pH, temperature and incubation time and the result showed that the strain BG7 produced maximum chitinase at pH of 7, temperature of 30 with 0.5 % colloidal chitin. This finding might be applied for the development of new B. thuringiensis formulations against seed and soil borne pathogens along with insecticidal toxins. [ABSTRACT FROM AUTHOR]

Background: Fusarium fujikuroi is the causal agent of bakanae, the most significant seed-borne disease of rice. Molecular mechanisms regulating defence responses of rice towards this fungus are not yet fully known. To identify transcriptional mechanisms underpinning rice resistance, a RNA-seq comparative transcriptome profiling was conducted on infected seedlings of selected rice genotypes at one and three weeks post germination (wpg). Results: Twelve rice genotypes were screened against bakanae disease leading to the identification of Selenio and Dorella as the most resistant and susceptible cultivars, respectively. Transcriptional changes were more appreciable at 3 wpg, suggesting that this infection stage is essential to study the resistance mechanisms: 3,119 DEGs were found in Selenio and 5,095 in Dorella. PR1, germin-like proteins, glycoside hydrolases, MAP kinases, and WRKY transcriptional factors were up-regulated in the resistant genotype upon infection with F. fujikuroi. Up-regulation of chitinases and down-regulation of MAP kinases and WRKY transcriptional factors were observed in the susceptible genotype. Gene ontology (GO) enrichment analyses detected in Selenio GO terms specific to response to F. fujikuroi: 'response to chitin', 'jasmonic acid biosynthetic process', and 'plant-type hypersensitive response', while Dorella activated different mechanisms, such as 'response to salicylic acid stimulus' and 'gibberellin metabolic process', which was in agreement with the production of gibberellin A3 in Dorella plants. Conclusions: RNA-seq profiling was performed for the first time to analyse response of rice to F. fujikuroi infection. Our findings allowed the identification of genes activated in one- and three- week-old rice seedlings of two genotypes infected with F. fujikuroi. Furthermore, we found the pathways involved in bakanae resistance, such as response to chitin, JA-dependent signalling and hypersensitive response. Collectively, this provides important information to elucidate the molecular and cellular processes occurring in rice during F. fujikuroi infection and to develop bakanae resistant rice germplasm. [ABSTRACT FROM AUTHOR]

Common bunt caused by Tilletia sp. is a very destructive and dangerous seed-borne fungal disease and may cause serious economic losses in worldwide. Wheat cultivars carrying resistance genes are used as an alternative fight method instead of chemical fungicides against common bunt disease. These resistance genes in wheat are called as bt genes. Until today, a few number of bt genes has been detected in wheat by using various molecular markers. However, development of more molecular markers for detection of all bt genes in wheat is required. In this study, detection of five bt genes called as bt-5, bt-8, bt-10, bt-11 and bt-12 was carried in ten registered local wheat varieties (Sertak 52, Bolal 2973, Demir, Kutluk, Harmankaya 99, Pehlivan, Tosun Bey, 4-11, Sönmez 01, Bezostaja-1) using PCR-based molecular markers, microsatellite and RAPD. PCR-amplified fragments were separated on 1.3% agarose gel. The obtained DNA bands were scored as present or absent for detection of bt genes. For comparison, the virulence rates of five Tilletia foetida (syn. leaves) isolates against ten wheat varieties were obtained from our field results. We observed that wheat varieties Kutluk and 4-11 carrying bt-10 and bt11 genes are more resistant to disease in field. [ABSTRACT FROM AUTHOR]

Cucumber angular leaf spot, caused byPseudomonas syringaepv.lachrymans(Psl), is one of the most devastating bacterial diseases in cucumber worldwide. Seedborne transmission of the pathogen is one of the principal modes for disease spread. To date, the detection ofPslis mainly achieved by culture methods, which are time and labour-consuming. In the present work, propidium monoazide (PMA) treatment combined with a quantitative real-time PCR (PMA-qPCR) assay was developed for quantifying viablePslcells in contaminated cucumber seeds. PMA selectively penetrates compromised membranes of dead cells and inhibits DNA amplification during real-time PCR. The primers, based on a 162-bp amplicon fromgap1gene, were highly specific forPslat the species level. PMA at 60 μmol L−1was suitable for selective quantification of viable cells. The limit of detection (LOD) of PMA-qPCR for detecting viable cells in bacterial suspension and artificially contaminated cucumber seeds was 3.25 × 102CFU·mL−1and 47.73 CFU·g−1, respectively. For naturally contaminated seeds, quantifiable levels of viable cells were observed in eight out of the 37 samples, and ranged from 103to 104CFU·g−1. This assay has been confirmed to be a rapid and selective method to quantify the viable cells ofPslin bacterial suspension and cucumber seeds. Application of the assay may potentially improve pathogen control and disease management. [ABSTRACT FROM PUBLISHER]

Early diagnosis of seedborne fungal pathogens is particularly important, as often, infected seeds appear symptomless; seed diagnosis can avoid uncontrolled propagation of pathogens through long-distance exchange of such material. This will prevent economic losses and unnecessary use of fungicides, so reducing costs and the introduction of toxic substances into the environment. Traditional techniques for detection of seedborne fungi are based on incubation and grow-out methods. Although these are frequently used because of their simplicity of application, they are time-consuming, require mycological skills, and are sometimes not sensitive enough to low levels of seed infection. Recently, new identification techniques, based on DNA analysis, have been applied and are very efficient due to high sensitivity and specificity. The most common technique is conventional PCR, while other recent techniques include nested PCR, to obviate low levels of target pathogens, multiplex PCR, to detect several pathogens simultaneously, real-time PCR, to quantify fungi on seeds, and magnetic-capture hybridization PCR. The main drawbacks of molecular methods are the inability to distinguish between vital and non-vital inocula, and the difficulty in obtaining quality DNA template, due to PCR inhibitors in seeds. To reduce inhibitory effects, several modified PCR protocols, such as loop-mediated isothermal amplification, and non-destructive testing methods have been developed. Loop-mediated isothermal amplification and next-generation sequencing have been widely applied in nucleic acid analysis and, given the numerous advantages provided, their application can be substantially extended in the future for detection of fungal pathogens in seeds. [ABSTRACT FROM AUTHOR]

Bacterial panicle blight caused by Burkholderia glumae is one of the most severe seed-borne bacterial diseases of rice in the world. Currently, this disease has affected many countries of Asia, Africa, South and North America. It is a typical example of the shifting from minor plant disease to major disease due to the changes of environmental conditions. Some virulent factors of B. glumae have been identified, including toxoflavins and lipases, whose productions are dependent on the TofI/TofR quorum-sensing system, and type III effectors. In spite of its economic significance, neither effective control measure for this disease nor resistant rice variety is currently available. In recent years, genomics, transcriptomics and other molecular methods have provided useful information for better understanding the molecular mechanisms underlying B. glumae virulence and the rice defence mechanisms against pathogens. For the prevention of this pathogen, our laboratory has developed a rapid and sensitive multiplex PCR assay for detecting and distinguishing B. glumae from other Burkholderia species. This improved understanding of B. glumae will shed new light on bacterial panicle blight disease management. [ABSTRACT FROM AUTHOR]

Verbascum blattaria (Scrophulariaceae family) is a hardy perennial species that is used for the edges and flower beds of low-maintenance gardens. Phoma novae-verbascicola causes light brown necrotic spots on the leaves of V. blattaria seedlings. In order to demonstrate the seed transmission of this pathogen, several V. blattaria seeds belonging to three samples collected in 2013, were tested in vitro to detect the presence of P. novae-verbascicola. Two samples were found to be contaminated and colonies of the pathogen were isolated from the tested seeds. Phoma novae-verbascicola was identified from the morphological features observed in vitro and through an ITS (Internal Transcribed Spacer) analysis. The virulence of one isolate was confirmed by means of a pathogenicity test. This work demonstrates that P. novae-verbascicola can be transmitted by affected V. blattaria seeds. [ABSTRACT FROM AUTHOR]

Bakanae disease, or “foolish seedling”, is a seed-borne disease of rice ( Oryza sativa L.). Infected plants can yield empty panicles or perish, resulting in a loss of grain yield. The disease occurs most frequently when contaminated seeds are used. Once the seeds are contaminated, the pathogen Fusarium fujikuroi spreads in the field. Therefore, infected plants must be screened at early developmental stages. This work proposes an approach to nondestructively distinguish infected and healthy seedlings at the age of 3 weeks using machine vision. Seeds of the rice cultivars Tainan 11 and Toyonishiki were inoculated with a conidial suspension of F. fujikuroi . The seedling were cultivated in an incubator for 3 weeks. The images of infected and control seedlings were acquired using flatbed scanners to quantify their morphological and color traits. Support vector machine (SVM) classifiers were developed for distinguishing the infected and healthy seedlings. A genetic algorithm was used for selecting essential traits and optimal model parameters for the SVM classifiers. The proposed approach distinguished infected and healthy seedlings with an accuracy of 87.9% and a positive predictive value of 91.8%. [ABSTRACT FROM AUTHOR]

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Fusarium basal rot of onion, caused by Fusarium oxysporum f.sp. cepae , is one of the leading causes of post-harvest and storage losses within the Western Cape region in South Africa. Several vegetative compatibility groups (VCGs) of F. oxysporum f.sp . cepae have been associated with bulb rot in mature onions in South Africa, of which VCG 0425 predominates. Our study investigated seed and seedling transplants as potential sources of inoculum of F. oxysporum f.sp. cepae, and whether VCG 0425 is associated with these materials . Fusarium isolation studies from 13 seed lots showed that seven of the seed lots were infected with either moderately or highly virulent F. oxysporum f.sp . cepae isolates. The infection frequency of seed lots was between 0.17 and 0.50%, and only two of the seed lots were infected with VCG 0425. The seedborne nature of F. oxysporum f.sp . cepae was confirmed by showing that a green fluorescent protein (GFP)-labelled F. oxysporum f.sp. cepae VCG 0425 transformant could be transmitted from infected soil to bulbs, and from there to the seed stalks and seeds. Onion seedling transplants from nurseries were also implicated as a source of inoculum. The incidence of F. oxysporum f.sp. cepae in nurseries increased as the season progressed from 2.7% at the 6-week-old growth stage to 5.7% at the 14-week-old stage. The F. oxysporum f.sp. cepae isolates from transplants were highly to moderately virulent. However, none of the isolates proved to be VCG 0425. Most (>86%) of the F. oxysporum isolates from seed and seedlings were not F. oxysporum f.sp. cepae and were not pathogenic to onion. Altogether, the results indicate that onion seed and seedlings are inoculum sources of F. oxysporum f.sp. cepae in the Western Cape Province, but that VCG 0425 is rarely associated with these sources. [ABSTRACT FROM AUTHOR]

In vitro evaluation was carried out on seed samples of wild and cultivated rocket cultivars, most frequently grown in Italy, and obtained from farms affected by the leaf spot caused by Alternaria japonica in Piedmont and Lombardy during the fall of 2010. Twelve seed samples were collected and assayed for the presence of A. japonica. The pathogen was isolated only from not disinfected seeds. Among the two seed samples of cultivated rocket (Eruca vesicaria), only one was infected by A. japonica at a level of one infected seed out of 800. Four out of ten samples of wild (Diplotaxis tenuifolia) rocket seeds were contaminated by A. japonica with the highest level of infection detected in a single sample of 3 out of 800. All tested isolates of A. japonica obtained from seeds were pathogenic on both wild and cultivated rocket. [ABSTRACT FROM AUTHOR]

Embellisia astragali is an important seedborne pathogenic fungus responsible for yellow stunt and root rot of standing milk vetch ( Astragalus adsurgens). The current detection methods that are based on culture and morphological identification are time-consuming, laborious and not always reliable. A PCR-based diagnostic method was developed with the species-specific primer pairs AatpF and AatpR designed from the sequence of the plasma membrane ATPase gene of E. astragali. The specificity of the primers was verified by PCR analysis of DNA from three strains of E. astragali and 19 isolates of nontarget fungi from other genera. A single 135-bp amplicon was detected only from E. astragali isolates, and no cross-reactions were observed with any other tested isolates. The detection limit of this new method was 5 pg of template DNA. The specific primers enabled the detection of E. astragali from the seed of standing milk vetch. This species-specific PCR method provides quick, simple, powerful and reliable detection of E. astragali. Significance and Impact of the Study PCR-based detection is fast, convenient, precise and sensitive compared to the traditional methods of pathogen detection. This study develops the first PCR method for the detection of Embellisia astragali in standing milk vetch seeds. The species-specific primer set designed from the plasma membrane ATPase gene of E. astragali can detect the pathogen. This assay could be applied in the standing milk vetch seed industry. [ABSTRACT FROM AUTHOR]

A protocol for the specific detection and quantification of ' Candidatus Liberibacter solanacearum' in carrot seeds using real-time PCR was developed. The bacterium was detected in 23 out of 54 carrot seed lots from 2010 to 2014, including seeds collected from diseased mother plants. The average total number of ' Ca. L. solanacearum' cells in individual seeds ranged from 4·8 ± 3·3 to 210 ± 6·7 cells per seed from three seed lots, but using propidium monoazide to target live cells, 95% of the cells in one seed lot were found to be dead. Liberibacter-like cells were observed in the phloem sieve tubes of the seed coat and in the phloem of carrot leaf midrib from seedlings. The bacterium was detected as early as 30 days post-germination, but more consistently after 90 days, in seedlings grown from PCR positive seed lots in an insect-proof P2 level containment greenhouse. Between 12% and 42% of the seedlings from positive seed lots tested positive for ' Ca. L. solanacearum'. After 150 days, symptoms of proliferation were observed in 12% of seedlings of cv. Maestro. ' Candidatus Liberibacter solanacearum' haplotype E was identified in the seeds and seedlings of cv. Maestro. No phytoplasmas were detected in seedlings with symptoms using a real-time assay for universal detection of phytoplasmas. The results show that to prevent the entry and establishment of the bacterium in new areas and its potential spread to other crops, control of ' Ca. L. solanacearum' in seed lots is required. [ABSTRACT FROM AUTHOR]

Aflatoxins are carcinogenic metabolites produced byAspergillus flavus. Rice seeds may be contaminated by it at the time of harvesting or during storage. Detection of aflatoxigenic strains by TLC and analysis of genetic variability among 50A. flavuscultures from seeds of various rice genotypes by PCR using 18 RAPD primers is reported here. About 58% isolates were aflatoxigenic whereas 42% were non-toxic. There were 246 bands and 48 haplotypes. Approximately 99% bands were polymorphic, and thus high degree of genetic variability was observed. All the primers were informative with PIC values of range 0.75–0.95. Seventeen RAPD markers were not found to be useful for the detection of aflatoxigenicA. flavus. However, one RAPD primer 3B could differentiate aflatoxigenic and non-toxigenic isolates to some extent. One allele of Primer 3B at approximately 480 bp was present in 85% aflatoxin non-producers and in 6% aflatoxigenic isolates. This information may be utilised for designing markers for differentiating toxic/non-toxic isolates ofA. flavus. [ABSTRACT FROM AUTHOR]

The economic impact of seedborne bacterial diseases on rice production provides a major motivation for research on seed health. This paper reports on the endophytic growth of a rifampicin-marked strain of the seedborne rice pathogen Pseudomonas fuscovaginae. The bacterium was found in most tested seeds indicating that, even without visible discolouration, seed transmission is possible. Crushed discoloured seeds contained more bacterial cells than did non-crushed discoloured seeds. These bacteria were released during seed soaking, contaminating clean seed and lowering seed germination. Cells of a rifampicin-resistant strain of P. fuscovaginae, which had been inoculated onto rice seeds, were subsequently recovered from different growth stages and from different rice tissues, thereby indicating endophytic colonization. These results have implications for seedling establishment, as symptomless seeds do not assure disease-free seeds, and the presence of seedborne bacteria results in poor germination and poor seedling establishment. Elimination of seedborne bacteria by soaking in sodium hypochlorite can increase seed germination. This could be used in developing control strategies, and, if practised regularly, reduce entry of seedborne disease-causing organisms into crops, resulting in lower disease pressure. [ABSTRACT FROM AUTHOR]

In the present study, 110 local and 125 imported rice (Oryzae sativa L.) seed samples comprising of 28 different varieties were analyzed for seed health using standard blotter paper method. Eighteen fungal species belonging to 8 fungal genera viz., Alternaria, Bipolaris. Curvularia, Fusarium, Nigrospora, Pyricularia, Phoma and Tellitia were found associated with local and imported paddy seed lots. Local paddy seed lots were found more infected with seed-borne fungi as compared to imported paddy seed lots. On local paddy seed lots, Curvularia lunata (10.2%) was most observed as predominant fungal species followed by Fusarium moniliforme (6.5%). On the other hand, in imported paddy seed lots Tellitia barclyana was found maximum in infection percentage (90%) followed by Fusarium moniliforme (7.6%). [ABSTRACT FROM AUTHOR]

Common bacterial blight ( Xanthomonas axonopodis pv. phaseoli ) is a seed-borne disease that is difficult to control in dry bean ( Phaseolus vulgaris L.). Laboratory and field studies were conducted over a two-year period to determine the effect of microwave radiation on navy (cv. Navigator and Envoy) and pinto (cv. AC Ole) bean. Laboratory tests resulted in a 12 to 25% decrease in germination following 50–60 s of radiation, while less than a 10% loss was observed between 0 and 40 s. Pathogen viability was also tested, however the incidence of pathogen infection was low and no correlation was observed between exposure time and the incidence of colonization. In field studies conducted at Morden, MB (2012) and Ridgetown and Exeter, ON (2012–2013) microwave radiation and two chemical seed treatments (copper hydroxide 53.8% and pyraclostrobin + fluxapyroxad + metalaxyl) were evaluated for their effect on emergence, disease infection, seed pick, yield and return on investment. The application of microwave treatment decreased emergence by up to 7%, but did not impact the other parameters measured. Chemical treatment alone or in combination with microwave treatment also did not affect emergence, disease incidence, yield, seed pick, or return on investment. [ABSTRACT FROM AUTHOR]