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Wheat is regarded as the prime source of dietary carbohydrate, protein in the majority of countries all over the world. Wheat growth, productivity and seed quality has been extensively hampered by the aggression of seed-borne pathogens during post-harvest storage. The present work focus on the efficacy of chitosan-based Ag2+ nanoparticles (Ag-CNPs) for the management of seed borne pathogens of wheat and their subsequent effects on growth, yield, and quality of harvested seeds. For this, healthy seeds of wheat were nanoprimed with Ag-CNPs and further inoculated with A. flavus so as to induce pathogenic stress. These seeds were sown in pots in a completely randomized block design and plants were raised from both nanoprimed and inoculated seeds, while plants were also raised from non-nanoprimed primed and uninoculated that served as control. Nanoprimed and pathogen inoculated seeds effectively increased vegetative growth such as (132.31 %), fresh weight (1.63-fold), dry weight (1.67-fold), and panicle length (137.03 %). and amplified the number of grains per spike, harvest index, ten kernel weight, and yield/plant, despite of pathogenic interference. Concomitantly, Ag-CNPs nano-priming enhances the harvested seed quality raised from pathogen inoculated seeds plants. The integrated density of the bands obtained in SDS-PAGE of variedly primed seeds revealed that Ag-CNP priming improved wheat's total protein profiling with a denser band intensity. The antioxidant enzymatic activity of CAT, POD, SOD, and NOX was traced maximum in Ag-CNPs primed seeds by 13.52, 7.90, 26.6 and 16.08 units, respectively. Thus, it can be concluded that nano priming with Ag-CNPs mitigated the wheat seeds from pathogenic stress and efficiently increased yield parameters and quality of harvested seeds.

The objective of this study was to determine the effects of seed treatments with boron on germination, seedling growth, and disinfection of seed-borne pathogens in safflower. Saf- flower seeds of the Balcı cultivar were treated with solutions of 0, 5, 10, and 20 ppm boron for 6 hours or surface treated with powdery sodium borate (Na2B8O13.4H2O). The experiment was a completely randomized design with eight replications and 25 seeds per replicate. Treated or untreated seeds were germinated between papers and germination characteristics, emergence, seedling growth, and infected seed rate were investigated. The results showed that the peak germination percentage (96.5%) was achieved in seeds primed with 5 ppm B. The mean germination time was significantly reduced, and the germination index reached the maximum value (23.5) in seeds primed with 5 ppm boron. Emergence percentage improved from 76.5% in the control to 87.5% in the seed dressing. The root and shoot length of the primed seeds increased fourfold. Seedling fresh weight was positively affected by the boron treatments, and seeds primed with 20 ppm boron produced the heaviest fresh seedlings. All boron treatments significantly reduced the infection rate by about 73%, but the lowest infection rate (11.5%) was observed in seeds primed with 5 ppm boron. It was concluded that safflower seeds should be primed with 5-10 ppm boron or at least undergo seed dressing with boron to reduce the negative effects of seed-borne pathogens and promote germination and seedling growth. [ABSTRACT FROM AUTHOR]

Colletotrichum truncatum and Sclerotinia sclerotiorum are fungal pathogens that can be disseminated by soybean seed, and they are usually controlled by seed treatment with fungicides. However, due to the harmful effects of pesticides on the environment and human health, the search for alternative methods to control seed-borne pathogens is necessary. Thus, this study evaluated whether the extract of Diaporthe infecunda, an endophyte from Schinus terebinthifolius leaves, inhibits the growth of C. truncatum and S. sclerotiorum, and improves the sanitary quality of soybean seeds. Initially, diffusion in agar assays with a D. infecunda extract were carried out. It was shown that the extract results in an inhibition of 94.4% and 83.8% of mycelial growth of C. truncatum and S. sclerotiorum, respectively. In a second study, soybean seeds were artificial inoculated with C. truncatum and S. sclerotiorum separately for each pathogen species with a water restriction technique using mannitol. The treatments consisted of: T1 = synthetic fungicide (thiophanate-methyl + fluazinam); T2 = D. infecunda extract (10 mg mL−1); T3 = solvent only (methanol:water); T4 = D. infecunda extract + fungicide; T5 = non-treated seeds; T6 = non-inoculated and non-treated seeds. The incidence of C. truncatum and S. sclerotiorum was reduced with the use of D. infecunda extract (12% and 10%, respectively) compared to the non-treated seeds (35% and 52%, respectively). However, there was a decrease in the seed germination with the D. infecunda extract. In conclusion, the extract of D. infecunda has potential to be used in seed treatment of soybean to control C. truncatum and S. sclerotiorum, however, further studies are required due to the decrease in seed germination. [ABSTRACT FROM AUTHOR]

Seed-borne pathogens in crops reduce the seed germination rate and hamper seedling growth, leading to significant yield loss. Due to the growing concerns about environmental damage and the development of resistance to agrochemicals among pathogen populations, there is a strong demand for eco-friendly alternatives to synthetic chemicals in agriculture. It has been well established during the last few decades that plant seeds harbor diverse microbes, some of which are vertically transmitted and important for plant health and productivity. In this study, we isolated culturable endophytic bacteria and fungi from soybean seeds and evaluated their antagonistic activities against common bacterial and fungal seed-borne pathogens of soybean. A total of 87 bacterial isolates and 66 fungal isolates were obtained. Sequencing of 16S rDNA and internal transcribed spacer amplicon showed that these isolates correspond to 30 and 15 different species of bacteria and fungi, respectively. Our antibacterial and antifungal activity assay showed that four fungal species and nine bacterial species have the potential to suppress the growth of at least one seed-borne pathogen tested in the study. Among them, Pseudomonas koreensis appears to have strong antagonistic activities across all the pathogens. Our collection of soybean seed endophytes would be a valuable resource not only for studying biology and ecology of seed endophytes but also for practical deployment of seed endophytes toward crop protection.

The pathogen Xanthomonas oryzae pv.oryzae (Xoo) is responsible for rice bacterial leaf blight (BLB), a disease that can significantly reduce rice yield by 60-80%. Xoo can also be transmitted through seeds, making it a seed-borne pathogen. Therefore, it is crucial for farmers to consider environmental factors when storing seeds. This research aims to determine the optimal temperature and packaging for storing rice seeds to prevent Xoo infection. The study employed a split-plot design, where the main plot consisted of two temperature treatments: low (4 ᵒC ± 2 ᵒC) and room temperature (28 ᵒC ± 3 ᵒC). The subplots focused on three packaging types: no packaging as a control, aluminum foil, and polyethylene plastic, resulting in a total of six treatment combinations. Seed pathology testing was conducted using the liquid assay method, while physiological testing utilized the growing on test method. The results revealed that plastic packaging at room temperature provided the most effective treatment for suppressing Xoo, exhibiting the lowest infectivity, number of colonies, and strength vigor index. Conversely, room temperature without packaging demonstrated the highest physiological quality in terms of seed germination and length. However, the temperature and packaging conditions are optimal for the growth of paddy seeds, i.e., at room temperature without packaging.

Seed-borne mycoflora can affect seed health and quality. The present study investigated the occurrence of seed-borne fungi in 600 seed samples of Avena sativa (B7) and A. nuda (B2) collected from Baicheng (BB), Dingxi (DB), and Haibei (HB) cities in China. Effects of seed-borne fungi on seed germination and seedling growth of oat were also studied. Among all isolated fungi, 10 fungal genera with high incidence were identified by colony color, spore morphology, and ITS sequence analysis, including Alternaria, Epicoccum, Fusarium, Bipolaris, Pyrenophora, Aspergillus, Cladosporium, Nigrospora, Pleospora, and Hypomyces. Alternaria spp. showed the highest incidence of 34.2%, while Nigrospora oryzae and Hypomyces sp. showed a lower incidence, 1.87% and 1.77%, respectively. The highest number of fungal species was isolated from HB-7 seeds compared to BB-2 which had the lowest species. Alternaria and Epicoccum were the dominant seed-borne species isolated from oat seeds in three regions, while B7 showed a higher infection incidence than B2. The pathogenicity tests of these seed-borne fungal pathogens against oat seed were conducted in the laboratory, and the results showed that the seed germination rate, germination potential, germination index, and vigor index of B2 and B7 seeds were significantly decreased by Alternaria spp., Bipolaris spp., C. allicinum, Pyrenophora sp., Fusarium spp., and N. oryzae (P < 0.05). The plumule length, radicle length, and dry weight of B2 and B7 seedlings were significantly reduced by Bipolaris spp. and Fusarium spp. (P < 0.05). Seed-borne fungal infection might inhibit seed germination and seedling growth of oat. [ABSTRACT FROM AUTHOR]

This article reports on the first documented case of seed decay and seedling damping-off of wheat caused by the seed-transmitted pathogen Alternaria rosae in Iraq. The study was conducted in the Karbala Governorate, where a survey of 13 wheat varieties revealed high rates of seed germination failure. The researchers collected seeds from different regions, disinfected them, and observed fungal colonies growing around the seeds. The isolates were identified as Alternaria rosae through DNA analysis and were found to be pathogenic to wheat seedlings. This study highlights the importance of ensuring seed quality in wheat production. [Extracted from the article]

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Seed-borne pathogens are a daily issue for ex situ collection managers who try to solve it using various chemicals more or less harmful to the staff and the plant material stored. The most common physical method for seed sterilisation is moist heat, in contrast to dry heat which is used much less frequently. Consequently, the efficiency of dry heat as disinfection method and the behaviour of seeds undergoing this treatment are currently poorly known, especially for wild species. In this study, seed viability was estimated by performing germination tests according to standard procedures. Germination tests were conducted on 13,200 seeds from 66 wild species of temperate regions belonging to 22 different families. Results indicate that dry seeds exposed to 60°C during 1hour were less infected by seed-borne pathogens in 14% of the cases, whereas no change has been registered in the other cases. For all 66 studied species, no decrease in germination percentage was detected after the heat treatment. Given its positive effect on infection control without affecting seed viability, dry heat treatment as proposed here opens opportunities for seed bank managers, but also for the disinfection of herbarium collections. [ABSTRACT FROM PUBLISHER]

Four experimental trials were carried out in order to evaluate the efficacy of different products (chemicals, resistance inducers and natural products) as well as heat air when applied to basil seeds naturally infested by Peronospora belbahrii, the causal agent of downy mildew of basil, a pathogen which is seed transmitted. Seed quality, as vigour index, was also evaluated. In general, seed treatment had a positive effect on the reduction of disease incidence and on plant biomass at the end of each trial, with very satisfactory results when disease incidence was lower than 10% and still satisfactory results with a higher disease incidence. Although many of the fungicides, resistance inducers and thyme oil treatments tested showed a significant disease reduction compared with the untreated control, the protection offered was only partial. Moreover, the effectiveness of the tested seed treatments varied considerably between the trials. The seeds treatment with heat air (65°C for 10 min) significantly reduced the number of infected plants per container. The interaction effect between the fungicides (at the lowest dosage tested, with the exception of acibenzolar-S-methyl, and dimethomorph), thyme oil and the heat air treatment was also significant. In terms of biomass, most treatments not significantly improved the fresh weight in comparison with the untreated control. The highest biomass was observed in the plots where seeds were dressed with mancozeb combined with heat air. Interestingly, thiram is also effective against other pathogens affecting basil and the thermal treatment and potassium phosphite are fully compatible with the rules of organic farming. Seed dressing represents the starting point of a full integrated approach for downy mildew management. [ABSTRACT FROM AUTHOR]

Knowledge about the mechanism of transmission of systemic pathogens of citrus species is highly important for the safe movement of citrus germplasm, management of citrus mother trees, and also production of young plants. Among systemic pathogens of citrus, Xylella fastidiosa the causal agent of the citrus variegated chlorosis (CVC), is one the most important pathogens causing decline in tree vigour and productivity. Seven-year experiments were conducted to evaluate the hypothesis of seed-to-seedling transmission of X. fastidiosa. This bacterium was found colonizing the fruit (exocarp, central axis and mesocarp) and the seed parts (seed coat and endosperm plus embryo). After 7 years of PCR assay, no positive PCR detection of X. fastidiosa was confirmed in seedlings propagated from the seeds infected with X. fastidiosa. This result demonstrates the lack of seed-to-seedling transmission of this bacterium. [ABSTRACT FROM AUTHOR]

In the years 2020-2021 as part of the activity of the Campania region hemp fiber project, variety comparison trials were carried out on 7 hemp varieties among those relevant for bast fiber production. During the trials, in particular on the cv. Fibrante, a consistent problem was noted: a noticeable germination failure (80-90%) occurred during the emergence of seedlings. Therefore, experiments were conducted to ascertain the possible presence of seed-borne pathogens. Tests were carried out on 100 seeds that were surface disinfected with 2% sodium hypochlorite solution for 3 min, rinsed in sterile distilled water three times and dried on sterile filter paper. The seeds were plated on potato dextrose agar (PDA Oxoid™) amended with 100 mg L-1 of streptomycin sulphate, kept at 24°C in the dark and observed daily. Growing colonies were subcultured on PDA for 10 days and, subsequently, twenty purified fungal isolates were obtained by single spore isolation. Colonies of these isolates on PDA were initially grayish-white and then turned dark olive green with abundant cotton-like aerial hyphae. On potato carrot agar (PCA) medium, these isolates produced light brown and solitary conidiophore with septum. Conidia were obclavate or pyriform, brown, with 1-3 transverse septa and 0-3 longitudinal septa, and measured 12.5 to 28.5 × 5 to 15 µm (n=50). The morphological characteristics observed under the light microscope were consistent with that of Alternaria spp. (Simmons 2007). In order to characterize the representative isolate, total DNA was extracted using the DNeasy Plant Mini Kit (Qiagen, Hilden, Germany) and 3 genes were PCR-amplified: the ITS spacer using the primer pair ITS1-ITS4 (White et al., 1990), the transcription elongation factor 1- using the primer pair EF1-983F/ EF1-2218R (Rehner and Buckley., 2005) and the RNA polymerase II second largest subunit (RPB2) using the primer pair RPB2-5F2/fRPB2-7cR (Sung et al 2007; Liu et al 1999). The size-expected amplicons were purified and sequenced at the BMR Genomics (Padova, Italy) and the resulting sequences were deposited in GenBank under the accession numbers ON556507, ON601003, ON601004. BLAST-n analysis revealed 98 to 99% nucleotide identity with some representative isolates of Alternaria rosae E.G. Simmons & C.F. Hill (KU375630.1, XM&#95;046169884.1, XM&#95;046168987.1). To fulfill Koch's postulates, 100 hemp-certified seed were disinfected as mentioned above, left to germinate on the water-agar to discard potentially infected seeds and finally sowed in sterile peat-soil mix (1:1 v/v). The inoculum consisted of 10 mL of 105 conidial suspension obtained by the representative isolate (Ar&#95;H1). Negative control seeds were inoculated with sterile water. After 5-7 days 100% of inoculated seedlings showed weak germinative vigor with yellowing of the epicotyls and dark areas on the root. The tissue narrowed and turned necrotic with abundant white mycelium covering the entire seedling. Small pieces of necrotic roots were plated on PDA and the same Alternaria-like colonies grew in 10 days. DNA sequencing confirmed the presence of A. rosae. Alternaria spp. are fungi that produce a wide range of toxic metabolites, harmful to food safety in the food uses of the seed. This finding further highlights that the quality of the hemp seed must be considered as a priority aspect in the entire hemp supply chain. To the best of our knowledge, this is the first report of A. rosae as seed-borne fungus on hemp.

Background Xanthomonads are plant-associated bacteria responsible for diseases on economically important crops. Xanthomonas fuscans subsp. fuscans (Xff) is one of the causal agents of common bacterial blight of bean. In this study, the complete genome sequence of strain Xff 4834-R was determined and compared to other Xanthomonas genome sequences. Results Comparative genomics analyses revealed core characteristics shared between Xff 4834-R and other xanthomonads including chemotaxis elements, two-component systems, TonBdependent transporters, secretion systems (from T1SS to T6SS) and multiple effectors. For instance a repertoire of 29 Type 3 Effectors (T3Es) with two Transcription Activator-Like Effectors was predicted. Mobile elements were associated with major modifications in the genome structure and gene content in comparison to other Xanthomonas genomes. Notably, a deletion of 33 kbp affects flagellum biosynthesis in Xff 4834-R. The presence of a complete flagellar cluster was assessed in a collection of more than 300 strains representing different species and pathovars of Xanthomonas. Five percent of the tested strains presented a deletion in the flagellar cluster and were non-motile. Moreover, half of the Xff strains isolated from the same epidemic than 4834-R was non-motile and this ratio was conserved in the strains colonizing the next bean seed generations. Conclusions This work describes the first genome of a Xanthomonas strain pathogenic on bean and reports the existence of non-motile xanthomonads belonging to different species and pathovars. Isolation of such Xff variants from a natural epidemic may suggest that flagellar motility is not a key function for in planta fitness. [ABSTRACT FROM AUTHOR]

Seed-borne pathogens in crops reduce the seed germination rate and hamper seedling growth, leading to significant yield loss. Due to the growing concerns about environmental damage and the development of resistance to agrochemicals among pathogen populations, there is a strong demand for eco-friendly alternatives to synthetic chemicals in agriculture. It has been well established during the last few decades that plant seeds harbor diverse microbes, some of which are vertically transmitted and important for plant health and productivity. In this study, we isolated culturable endophytic bacteria and fungi from soybean seeds and evaluated their antagonistic activities against common bacterial and fungal seed-borne pathogens of soybean. A total of 87 bacterial isolates and 66 fungal isolates were obtained. Sequencing of 16S rDNA and internal transcribed spacer amplicon showed that these isolates correspond to 30 and 15 different species of bacteria and fungi, respectively. Our antibacterial and antifungal activity assay showed that four fungal species and nine bacterial species have the potential to suppress the growth of at least one seed-borne pathogen tested in the study. Among them, Pseudomonas koreensis appears to have strong antagonistic activities across all the pathogens. Our collection of soybean seed endophytes would be a valuable resource not only for studying biology and ecology of seed endophytes but also for practical deployment of seed endophytes toward crop protection.

Aims: To evaluate the effectiveness of the optimized immunomagnetic separation (IMS)-plating protocol in relation to other culture, serological and molecular techniques currently used for Clavibacter michiganensis subsp. michiganensis in seed-testing laboratories. Methods and results: Bacterial suspensions, tomato seed extracts spiked with the pathogen and naturally infected seeds were IMS-plated for the detection of C. m. subsp. michiganensis. These results were compared with plating on general (YPGA) and semiselective (mSCM) media, double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), immunofluorescent assay (IF) or polymerase chain reaction (PCR). Different seed lots and pathogen strains were also tested. IMS-plating allowed the detection of less than 10 CFU ml−1 of pathogen in all assayed samples. The mSCM medium provided positive results for 10 CFU ml−1 in naturally infected seeds, but up to 14 days was necessary for the typical colonies of the target to be come visible. By serological techniques, 103 and up to 104 CFU ml−1 were detected by IF and ELISA, respectively. DNA extraction was required to obtain positive results by PCR in seed extracts containing 103 CFU ml−1 or more. Conclusions: Among the evaluated methods, IMS-plating provided the best results regarding sensitivity and specificity for C. m. subsp. michiganensis detection, allowing the recovery of viable bacteria from seed extracts. Significance and impact of the study: IMS-plating increases isolation rates of C. m. subsp. michiganensis and could improve standard protocols currently used for routine analysis. [ABSTRACT FROM AUTHOR]

Bacterial leaf spot symptoms of coriander were first observed in January 2003 in three coriander fields in the valley region of the Axarquía (Málaga, Spain), showing a very high incidence.Pseudomonas syringaepv.coriandricolawas consistently isolated from diseased plants, identified and its pathogenicity on coriander could be proved. The effective inoculum dose (ED50) of the isolated strains was estimated and it was very similar to those displayed by theP. syringaepv.coriandricolareference strains used as control. This is the first report of bacterial leaf spot on coriander in Spain. [ABSTRACT FROM AUTHOR]

Very little information is currently available concerning the pathogenic determinants produced by Alternaria brassicae, the causal agent of the blackspot disease of crucifers. We screened a genomic library of this fungus and identified a nonribosomal peptide synthetase (NRPS) gene named AbrePsy1. The complete coding sequence is 22 kbp long and encodes a large protein (792 kDa) showing typical NRPS modular organization. Structural analysis of AbrePsy1 revealed four complete elongation modules, two of which have epimerization domains. In the vicinity of AbrePsy1, a second gene (named AbreAtr1), which encodes an ATP-binding cassette transporter was identified. Increased expression of AbrePsy1 and AbreAtr1 was observed during host-plant infection. However, while physically linked, these two genes are probably not functionally clustered, as their expression patterns differed. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate in vitro the mycelial susceptibility of Trichoconiella padwickii to different active ingredients through average median concentration IC 50 calculation. Inoculum disks were seeded on bean agar at different concentrations (0.1; 1; 10; 30, 50; 100 and 1000mg/l) of various fungicides. After seven days the colony diameter was measured. The data obtained were fitted to nonlinear regression models. Susceptibility was classified using the scale proposed by Edgington. The results show that the pathogen is very sensitive to products that act on the respiratory chain (quinone outside inhibitors [QoI] and succinate dehydrogenase inhibitors [SDHI]) and cell membrane (multi-site contact activity), and moderately sensitive to those products interfering with cell division (methyl benzimidazole carbamates [MBC]), synthesis of nucleic acids (phenylamides [PA]) and osmotic signal transduction (multi-site contact activity). This work is the first record on the sensitivity of T. padwickii., (Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.)