Seed-borne Fungal Diseases Research Articles

In-vitro and In-vivo Management of Seed Borne Fungal Diseases of Maize

In-vitro and In-vivo Management of Seed Borne Fungal Diseases of Maize

Progress in Research on Prevention and Control of Crop Fungal Diseases in the Context of Climate Change

With an advancement in global climate change, the frequency of extreme climatic events, such as high temperature, drought, and flooding, has increased. Meanwhile, outbreaks of crop fungal diseases are becoming more frequent and serious, and crop growth and food production are seriously threatened. This article focuses on the climate change-related aggravation of crop fungal diseases; summarizes the progress in research on the impact of climate change on soil-borne fungal diseases, air-borne fungal diseases, and seed-borne fungal diseases; and discusses the conventional methods for diagnosing crop fungal diseases. On the basis of comparative analysis, the concept of ecological control is proposed; ecological control can maintain the dynamic balance of crop–biology–soil, provide a good environment for the healthy growth of crops, and provide a new fungal disease control method in the context of climate change.

Seed dressing with M451 promotes seedling growth in wheat and reduces root phytopathogenic fungi without affecting endophytes.

Fungal plant infections result in substantial losses to the agricultural sector. A range of fungicide seed dressings are available to control seed-borne fungal diseases; however, they lack sufficient efficacy because of intrinsic tolerance and acquired resistance. Moreover, many fungicide seed dressings can also penetrate plants, negatively affecting plant growth owing to their toxic effects on endophytes, as well as contributing to the spread of antibiotic resistance. Here, we evaluated the efficacy of M451, a member of a new class of antimicrobial agents that are not relevant to human healthcare. As a seed dressing for wheat seeds, M451 exhibited significant antifungal activity against one of the most devastating plant fungal pathogens, Fusarium spp. Furthermore, M451 was more active than the commercially used fungicide Maxim XL against both seed-borne and soil-borne F. oxysporum infection. Importantly, and unlike other antifungals, M451 seed dressing did not inhibit any of the major characteristics of wheat grains and seedlings, such as germination percentage, germination time, grain vigor, shoot- and root weight and length, but rather improved some of these parameters. The results also demonstrated that M451 had no negative impacts on endophytes and did not accumulate in grains. Thus, M451 may have potential applications as an antifungal agent in wheat cultivation.

Seed-Borne Fungi Associated with Diverse Rice Varieties Cultivated in the Western North Region of Ghana.

Rice is a major staple in the Ghanaian diet. However, its production is constrained by fungal diseases. A survey was conducted in 2018 in three selected districts in the Western North Region of Ghana using a structured questionnaire and face-to-face interaction with 230 farmers to assess their knowledge, perceptions of seed-borne fungal diseases, and management practices. Additionally, fungi associated with farmer's seeds were isolated and identified through the Agar and Blotter tests. Findings indicate that 72.7% of the farmers in the selected districts relied on their saved seeds for planting. Thirteen fungal genera were associated with the rice seed samples collected from the three districts. The Juaboso district had the majority (13) of seed-borne fungi. The seed samples were categorized into various forms of discolouration, and significant differences (P < 0.05) existed among the seed samples for this parameter. The AGRA rice, a farmer-saved seed from Juaboso, had the highest level of seed discolouration (41.96%). Fungi identified to be associated with the dark brown/brown discolouration of rice seeds were Bipolaris spp., Fusarium spp., Macrophomina phaseolina and Aspergillus spp. The only fungus associated with the yellow/pale yellow colour was Bipolaris spp. The fungi Bipolaris spp., Curvularia spp., and Botryodiplodia spp. were associated with the dark spot discolouration. Alternaria spp., and Aspergillus spp. were observed on the greyish white seed discolouration sample. Fungi are associated with rice cultivation and vary according to district and rice variety. A complex of pathogenic and saprophytic fungi therefore infects rice grains both in field and storage conditions.

Seed Endophytic Achromobacter sp. F23KW as a Promising Growth Promoter and Biocontrol of Rhizoctonia Root Rot of Fenugreek.

Root rot is one of the most significant soil and seed-borne fungal diseases, limiting the cultivation of fenugreek plants. Endophytic bacteria and their natural bioproducts have emerged as growth promoters and disease suppressors in the current era. Despite limited research, seeds are a good funder of endophytic microbiomes, which are transmitted from them to other seedling parts, thereby providing a shield against biotic and abiotic anxiety and promoting the growth at early germination and later stages. The current study evaluated the hypothesis that seed endophytic bacteria and their lytic enzymes, growth promotors, and antifungal molecules can induce growth, and inhibit root rot disease development at the same time. The isolation trial from fenugreek seeds revealed a lytic Achromobacter sp., which produces indole acetic acid, has antifungal compounds (e.g., 2-Butanol, 3,3’-oxybis-), and reduces the growth of Rhizoctonia solani by 43.75%. Under the greenhouse and natural field conditions, bacterial cells and/or supernatant improved the growth, physiology, and yield performance of fenugreek plants, and effectively suppressed the progress of root rot disease; this is the first extensive study that uses a new seed-borne endophytic bacterium as a plant-growth-promoting, and biocontrol tool against the sclerotia-forming; R. solani; the causative of fenugreek root rot.

Afterglow of atmospheric non-thermal plasma for disinfection of lentil seeds from Botrytis Grey Mould

Seed-borne fungal diseases of grains are a serious threat to grain crops' yield due to lack of either resistant crop varieties or dependence on fungicides. Therefore, there is a growing demand to develop sustainable technologies for crop protection. In the present study, an atmospheric microwave plasma was employed to eradicate Botrytis cinerea from lentil seeds. Argon, air and a combination of them were applied to create the plasma. There was a 41% reduction in the percentage of artificially contaminated seeds (with an initial contaminated seed percentage of 95.8%) after 100 s treatment of 2.5 g of lentil seeds with the afterglow of air plasma followed by 24-h holding time. A 32.3% reduction occurred when a 30% air/70% Argon was applied for 10 s and 60 min of holding time. The holding time of 24 h increased catalase activity from 0.8 to 1.1 mM H2O2 mg−1 min−1 that was an indicator of early plant immune system fortification. This also changed seeds' colour toward redness and yellowness. Conclusively, the afterglow of microwave plasma could be considered as a part of integrated disease management in lentil crops.

Diversity of the Seedborne Fungi and Pathogenicity of Fusarium Species Associated with Intercropped Soybean.

Maize/soybean relay strip intercropping has been widely practiced in Southwest China due to its high productivity and effective application of agricultural resources; however, several seedborne diseases such as seedling blight, pod and seed decay are frequently observed causing severe yield loss and low seed quality. So far, the population and pathogenicity of the seedborne fungi associated with intercropped soybean remain unexplored. In this study, seeds of 12 soybean cultivars screened for intercropping were collected from three growing regions in Sichuan Province of Southwest China, and the seedborne fungi were isolated from the surface-sterilized seeds. Based on sequence analysis of ribosomal DNA internal transcribed spacer (rDNA ITS), 148 isolates were identified into 13 fungal genera, among which Fusarium covered 55.0% as the biggest population followed by Colletotrichum. Furthermore, Fusarium isolates were classified into five distinct species comprising F. fujikuroi, F. proliferatum, F. verticillioides, F. asiaticum and F. incarnatum through sequence analysis of translation elongation factor 1 alpha (EF-1α) and DNA-directed RNA ploymerase II second largest subunit (RPB2). Among them, F. fujikuroi accounted for 51.22% (42/82) and was isolated from 91.7% (11/12) soybean varieties. Pathogenicity assay showed that five Fusarium species were able to infect the seeds of soybean cultivar “Nandou12” and caused water-soaked or rot symptoms, while F. fujikuroi and F. asiaticum had much higher aggressiveness than other species with significant reductions of seed fresh weight and germination percentage. Accordingly, this study indicates that Fusarium species are the dominant seedborne fungi in the intercropped soybean in Sichuan, China, and this provides some useful references for the effective management of seedborne fungal diseases as well as soybean resistance breeding in maize/soybean relay strip intercropping.

Nano-diagnostic technique for detection of rice pathogenic fungus Pyricularia oryzae

Rice blast caused by Pyricularia oryzae is considered as one of the most dangerous diseases in Egypt and worldwide. The fungus can infect rice plants at any growth stage. P. oryzae can be transmitted from seeds to seedlings and increase the possibilities of spreading the disease and could cause epidemics, so that blast was referred to seed-borne disease. Current investigation aimed to develop an advanced technique or procedure that would allow reliable, reasonably fast and accurate detection of dangerous seed-borne fungal diseases such as P. oryzae in rice. The most common seed health tests including washing test (WT), blotter method (BM), washing after incubation, modified (WAI), deep freezing method (DF) and potato dextrose agar method (PDA) were applied for detecting seed-borne fungi from rice seeds. Among other fungi, the blast fungus P. oryzae was recorded only for three times from rice seed samples with very low frequency values of 1.0 and 1.5 in 2015 season using WT and WAI, respectively, and 2.0 in 2016 season using WAI. PCR has many beneficial characteristics that make it highly applicable for detecting P. oryzae in seeds. So that, side by side, PCR reaction was used for detecting and identifing P. oryzae to overcome the time consuming and inacuracy of the common seed heath tests. Metallic nanoparticles, silver and iron oxide nanoparticles were also involved to enhance DNA extraction which considered an important step in the PCR technology. Silver and Iron oxide nanoparticles were able to enhance the quantity and purity of DNA template for successful PCR assay. Preferably, seed health methods should be sensitive, specific, rapid, robust, inexpensive and simple to be applicable and fit for plant quarantine purposes. Many detection methods occur for different seed-borne pathogens, but, few of the minimum requirements for adequate seed tests were satisfied. In conclusion Nano based PCR method could be applied as an appropriate test for rapid detection of rice pathogenic fungus P. oryzae.

Plasma mediated disinfection of rice seeds in water and air

The efficacy of seed disinfection utilizing atmospheric pressure non-thermal plasma is still a subject of intensive research. Previously, we found that rice seeds infected by Fusarium fujikuroi (fungus causing bakanae disease) could be disinfected via underwater arc discharge plasma. In this study, we further investigated the mechanism of disinfection and the effect on disease severity. In addition, we evaluated disinfection of rice seeds in air by surface DBD plasma. Disease severity was significantly reduced in seedlings germinated from rice seeds treated with underwater arc plasma, compared to non-treated seeds (44%–62% plasma treated compared to 92% non-treated). A shockwave of 11 atm pressure was generated during arc discharge, which likely caused fungal detachment from the seed surface. Moreover, reactive oxygen species such as atomic oxygen (O) was emitted from the underwater arc discharge plasma and could have contributed to the degeneration of the chemical composition on the seed surface and the inactivation of the fungal spores. Rice seeds treated with surface DBD plasma in the presence of H2O2 at a lower pressure (0.6 atm) for 30 min showed the highest seed disinfection efficiency (about 93% seed disinfection) and a significant reduction in disease severity in the germinated seedlings (23% plasma-treated compared to 100% non-treated). Taken together, our results suggested that underwater arc discharge and surface DBD plasma could be usefully applied to develop control strategies for seed-borne fungal diseases via seed decontamination during dry storage or water imbibition before sowing.

ADVANCED TECHNIQUES FOR DETECTION OF IMPORTANT SEED-BORNE FUNGAL DISEASES IN SOME CEREAL CROPS

The Aims of this study were to: The first aim of the present study was to develop seed health methods that would allow reliable and reasonably fast detection of seed-borne fungal diseases such as Pyricularia oryzea in rice, Ustila.go tritici in wheat and Cephalosporium maydis in maize. Many detection methods occur for different seed-borne pathogens, but, few of the minimum requirements for adequate seed tests were satisfied. Preferably, seed health methods should be sensitive, specific, rapid, robust, inexpensive and simple to implement and interpret, in order to fit plant quarantine Some standard seed health procedures were applied for seed-borne fungi detection from the three seed crops. Washing test, Blotter method, Washing after Incubation (modified), Deep Freezing method and Potato Dextrose Agar method (PDA) were used in case of rice seed samples. Embryo Count method and Field experiment were carried out for loose smut detection. Blotter mehtod, Deep Freezing mehtod and Potato Dextrose Yeast Agar method were implimented in inspecting whole seeds and broken one of maize seed samples. Side by side, PCR detection and identification of the previously seed-borne pathogen was comparabley applied to face the disadvantages of the common tests. Nano-metalic particles were involved in to enhance of DNA and focused to compare between some traditional detection methods and advanced PCR-based techniques for detection of seed-borne pathogens in the three major food crops; wheat, rice and maize.

Problems of seed-borne fungal diseases affecting sorghum grain (Sorghum bicolor L. Moench) in two districts of Oromia, Ethiopia

Problems of seed-borne fungal diseases affecting sorghum grain (Sorghum bicolor L. Moench) in two districts of Oromia, Ethiopia

Differential Inactivation of Fungal Spores in Water and on Seeds by Ozone and Arc Discharge Plasma.

Seed sterilization is essential for preventing seed borne fungal diseases. Sterilization tools based on physical technologies have recently received much attention. However, available information is very limited in terms of efficiency, safety, and mode of action. In this study, we have examined antifungal activity of ozone and arc discharge plasma, potential tools for seed sterilization. In our results, ozone and arc discharge plasma have shown differential antifungal effects, depending on the environment associated with fungal spores (freely submerged in water or infected seeds). Ozone inactivates Fusarium fujikuroi (fungus causing rice bakanae disease) spores submerged in water more efficiently than arc discharge plasma. However, fungal spores associated with or infecting rice seeds are more effectively deactivated by arc discharge plasma. ROS generated in water by ozone may function as a powerful fungicidal factor. On the other hand, shockwave generated from arc discharge plasma may have greatly contributed to antifungal effects on fungus associated with rice seeds. In support of this notion, addition of ultrasonic wave in ozone generating water has greatly increased the efficiency of seed disinfection.

Seed Borne Fungal Diseases of Fruits in Mymensingh District

An experiment was conducted to evaluate the major seed borne fungal diseases of fruits in Mymensingh. Being perishable crop the fruits were found easily prone to the attack of various disease causing organisms at almost all sphere of their production practices from orchard to the storage, transit and consumption. Fruit rot (Botryodiplodia theobromae) and anthracnose (Colletotrichum gloesporioides) were found as the most common and serious diseases in many fruits such as mango, guava, banana, papaya, pineapple etc. Prevalence of the diseases, losses incurred and probable control measures have been suggested in most of the cases.J. Environ. Sci. &amp; Natural Resources, 8(1): 153-156 2015

Effects of Plant Extracts on Controlling Seed Borne Fungi of Okra (Abelmoschus esculentus L. Moench)

An experiment was conducted using farmer’s okra (Abelmoschus esculentus L. Moench) seeds in Seed Pathology Centre, Bangladesh Agricultural University, Mymensingh to determine the efficacy of plant extracts (garlic, allmanda, neem, ginger and biskathali extracts) and vigour index of seedling for controlling the seed-borne fungal diseases of okra. In the laboratory experiment, the prevalence of seed-borne fungi associated with farmer’s okra seed investigated by blotter method. The identified fungi species in the collected seeds were Colletotrichum dematium, Macrophomina phaseolina, Fusarium oxysporum, Aspergillus flavus, Aspergillus niger, Penicillium spp. and Rhizopus spp. The test seed materials were treated with garlic tablet, allmanda tablet @ 1:1 and 2:1 w/v and neem extract, ginger extract and biskathali extract @ 1:1 and 1:2 w/v for each to control pathogens with control treatment. The significantly highest germination (62.5%) and lowest incidence of pathogen (5.25%) were recorded in garlic tablet @ 2:1 w/v treated seeds. The okra seeds treated by garlic tablet @ 2:1 w/v was also showed the higher vigour index (545.60%) compare to untreated seed (423.40%).DOI: http://dx.doi.org/10.3329/jesnr.v7i2.22212 J. Environ. Sci. &amp; Natural Resources, 7(2): 85-88 2014

Evaluation of bio agents, botanicals and fungicides against the seed mycoflora of soybean

The soybean is the prime oil seed crop and the sources of protein cultivated all over the world. Seed borne diseases are of the important concern with regard to low productivity. The seed borne fungal diseases can be controlled if the seeds are treated with effective chemical and biological fungicides. In the present investigation seed borne fungi were evaluated against the bio agent, plant extracts and chemical fungicides. The best results were exhibited by chemical fungicides followed by bio agent and botanicals.

Supression of seed borne Cladosporium herbarum on common bean seed by Trichoderma harzianum and promotion of seedling development

Trichoderma harzianum isolates have been broadly used for biocontrol of plant diseases caused by fungi. Cladosporium herbarum is a common saprophyte and seed borne fungus, which is easy to manipulate under controlled conditions. It was chosen as a model to test the effectivity of seed treatments with T. harzianum. Common bean seeds (cv. Perola) contaminated with C. herbarum were treated with conidial suspension (CS) and autoclaved filtrate (AF) of five isolates of T. harzianum and subsequently submitted to health and germination tests. The proportion of normal seedlings formed, the length of roots, hypocotyls and leaves, and total plantlet length, total plantlet biomass, root mass ratio (RMR), stem mass ratio (SMR), leaf mass ratio (LMR), aerial part/root system ratio (AP/RS) and leaf area were also evaluated. Isolates CEN289 and CEN290 (CS and AF) provided 66 to 77% of supression of C. herbarum on seeds and a higher number of normal seedlings as compared with control. It also yielded a higher total biomass of plantlets. Moreover treatment with isolates CEN289 and CEN290 increased root and stem length in the experiments with CS. Such results indicate the potential of T. harzianum for seed treatment and suggest that it should be further tested as control for seed borne fungal diseases and as a plant growth promoter. The better performance found for CEN289 and CEN290 confirms the variability in terms of biocontrol activity among strains of T. harzianum.

Effect of plant extracts and an essential oil on the control of brown spot disease, tillering, number of panicles and yield increase in rice

The effects of essential oils (EO), cold water (CWE), hot water (HWE) and ethanol (ETHE) extracts of Callistemon citrinus L. and Cymbopogon citratus (DC) Stapf on the radial growth of Alternaria padwickii (Ganguly) M.B. Ellis and Bipolaris oryzae (Breda de Haan) Shoemaker, the control of brown spot disease, the tillering, the number of panicles and the yield increase in rice were evaluated under laboratory and field conditions. In vitro, the growth of both fungi was completely inhibited by the EO of C. citrinus and C. citratus at 4,520 μg/ml and 452 μg/ml, respectively. For solvent extracts, the ETHE of C. citrinus was the most active and inhibited 80–85 % of the fungal growth followed by the CWE of C. citratus with 77 % and 36 % diameter reduction against B. oryzae and A. padwickii, respectively at 10 000 μg/ml. Under laboratory conditions, seed treatment with the EO of C. citrinus reduced the incidence of B. oryzae in seeds by 85–100 % compared to the non-treated controls. Similarly, the seed treatment increased the germination of an irrigated rice cultivar by 10.6 %, whereas the percentage of germinated seeds of upland rice was not significantly affected. The highest germination (85–94 %) was found in the non-treated and treated samples with a low incidence (0–4 %) of B. oryzae. Under field conditions, the combined use of the essential oil of C. citrinus as a seed treatment and spraying the plants with 2 % ethanol followed by 2 % (w/v) aqueous extracts of C. citrinus or C. citratus increased the emergence, tillering, panicles/plant and the grain yield by 25–55 % of the irrigated rice. In addition, the brown spot severity was reduced by 36–42 %. For the upland rice, the treatments led to similar results with the grain yield increase of 54–137 % and 20–80 % reduction in the brown spot severity. From our results, we concluded that the EO and solvent extracts of C. citrinus and C. citratus have potential as control agents against brown spot and other seed-borne fungal diseases in rice under both conventional and organic farming.

Effect of BAU-Biofungicide and Plant Extracts on Seedling Vigour of Maize

An experiment was conducted in Seed Pathology Center, Bangladesh Agricultural University, Mymensingh to determine the efficacy of biocontrol means (BAU-Biofungicide, Garlic extract and Neem extract) and vigour index of seedling for controlling the seedborne fungal diseases of maize. In laboratory experiment, the prevalence of seed-borne fungi associated with maize cultivar cv. BARI Bhutta - 6 were investigated by blotter method. The identified fungi species were A. niger, A. flavus, Fusarium sp., P. oxalicum, C. lunata and R. stolonifer. The test materials were treated with BAU-Biofungicide @ 2.5% of seed weight, neem extract @ 1:2 w/v and 1:3 w/v and garlic extract @ 1:2 w/v and 1:3 w/v to control the pathogens. Significantly, the highest germination (87.%) and the lowest incidence of pathogen (4%) was recorded in BAU-Biofungicide treated seed The maize seeds treated by BAU- Biofungicide also show the higher vigour index (2856) followed by neem extract (1:2) treated seed (2621) after germination.DOI: http://dx.doi.org/10.3329/jesnr.v5i2.14602 J. Environ. Sci. &amp; Natural Resources, 5(2): 59-61 2012

Effect of Seed-borne Fungi on the Germinating Seeds and their Bio-control in Maize

An experiment was conducted in Seed Pathology Center, Bangladesh Agricultural University, Mymensingh to determine the efficacy of biocontrol means (BAU-Biofungicide, Garlic extract and Neem extract) in controlling seedborne fungal diseases of maize (Zea mays). In laboratory experiment, the seeds of maize cultivars cv. Badsha-1, Khai Bhutta, Bornali, Mohor, BARI Bhutta- 5 and BARI Bhutta- 6 were tested by blotter method. The identified fungi associated with the seeds were A. niger, A. flavus, Fusarium sp., P. oxalicum, C. lunata and R. stolonifer. The seed samples were treated with BAU-Biofungicide @ 2.5% of seed weight, neem extract@ 1:2 w/v and 1:3 w/v and garlic extract @ 1:2 w/v and 1:3 w/v to control the seed-borne pathogens. The effective results were recorded as regards to the highest germination (84.5%) reflected the lowest disease incidence (4.0%) recorded in BAUBiofungicide treated seeds followed by other treatment. DOI: http://dx.doi.org/10.3329/jesnr.v5i1.11564 J. Environ. Sci. &amp; Natural Resources, 5(1): 117 - 120, 2012

Role of leaf extracts of some medicinal plants in the management of seed-borne fungal diseases of Okra (Abelmoschus esculentus (L.) Moench)

In order to manage the fungal pathogens in okra, seeds of variety Arka Anamika were subjected to soaking treatment with the aqueous leaf extracts of Coleus aromaticus, Adathoda vasica, Vitex negundo, Solanum nigrum, Leucas aspera, Ocimum sanctum and Catharanthus roseus. Among the extracts used, Coleus aromaticus, Vitex negundo extracts were found superior in reducing the incidence of mycoflora. These leaf extract treatments also resulted in increased percentage of seed germination and vigour of the seedlings. Both in greenhouse and field conditions, these extracts proved their efficiency in the enhancement of biomass, number of leaves, number of seeds per fruit, seed density and ascorbic acid content in the raw fruits.