Search

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]

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.

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]

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_046169884.1, XM_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_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]

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.)