Pantoea species (Pantoea spp.) is a diverse group of Gram-negative bacteria in the Enterobacteriaceae family that leads to devastating diseases in rice plants, thus affecting significant economic losses of rice production worldwide. Most critical rice diseases such as grain discoloration, bacterial leaf blight, stem necrosis and inhibition of seed germination have been reported to be caused by this pathogen. To date, 20 Pantoea spp. have been identified and recognized as having similar phenotypic and diverse characteristics. Detection via phenotypic and molecular-based approaches, for example the polymerase chain reaction (PCR) and multiplex PCR give us a better understanding of the diversity of Pantoea genus and helps to improve effective disease control strategies against this emergent bacterial pathogen of rice. In this review, we focused on the significance of rice diseases caused by Pantoea spp. and insights on the taxonomy and characteristics of this destructive pathogen via phenotypic and molecular identification.
The aim of this review is to describe ecological and physiological features of Andrallus spinidens Fabricius and to discuss various possibilities of using it as an appropriate biocontrol agent in different agroecosystems. This hemipteran is a cosmopolitan predator of caterpillar pests of rice, wheat, soybean, moong, pigeon pea, maize, sugarcane and cowpea with special feeding on Chilo suppressalis Walker, Naranga aenescnes Moore, Helicoverpa armigera Hübner and Spodoptera litura Fabricius. Climate, spatial distribution of prey and type of agricultural crop are among the factors influencing the biology and spatial-temporal distribution of A. spinidens. Studies have shown random or aggregated distribution of the predatory bug with population peaks in April, July and October. The 1st instar nymphs have no feeding, the 2nd and 3rd (the first 2 days) instars are seedling feeders while they are voracious predators of caterpillars from the middle of 3rd instar to adulthood. The salivary gland consisted of two anterior-, two lateral- and two posterior lobes with major secretion of trypsin, chymotrypsin, amino- and carboxypeptidases. The alimentary canal has a four-sectioned midgut in which the third section seems to be the main place for digestive enzymes including α-amylase, trypsin, chymotrypsin, elastase cathepsins B, L and D as well as carboxy- and aminopetidases. Andrallus spinidens have shown compatibility with some insecticides and the entomopathogenic fungus, Beauveria bassiana. The predatory bug may be successfully reared in a laboratory using Galleria mellonella larvae as prey and both conservation and augmentation should be considered as biological control strategies against insect pests.
In the spring of 2019, many plants, mainly winter wheat, were observed to have dwarfism and leaf yellowing symptoms. These plants from several regions of Poland were collected and sent to the Plant Disease Clinic of the Institute of Plant Protection – National Research Institute in Poznań to test for the presence of viral diseases. Double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) results showed numerous cases of Wheat dwarf virus (WDV) and a few cases of plant infections caused by Barley yellow dwarf viruses (BYDVs). WDV was detected in 163 out of 236 tested winter wheat plants (69.1%), in 10 out of 27 tested winter barley plants (37%) and in 6 out of 7 triticale plants (85.7%) while BYDVs were found, respectively, in 9.7% (23 out of 236) and in 18.5% (5 out of 27) of tested winter forms of wheat and barley plants. Infected plants came mainly from the regions of Lower Silesia and Greater Poland. Furthermore, individual cases of infections were also confirmed in the following districts: Lubusz, Opole, Silesia, Kuyavia-Pomerania and Warmia-Masuria. Results of Duplex-immunocapture-polymerase chain reaction (Duplex-IC-PCR) indicated the dominance of WDV-W form in wheat and WDV-B form in barley plants. Moreover, results of reverse transcription – polymerase chain reaction (RT-PCR) connected with restriction fragment length polymorphism (RFLP) analysis, performed for 17 BYDVs samples, revealed 8 BYDV-PAS, 4 BYDV-MAV and 2 BYDVPAV as well as the presence of two mixed infections of BYDV-MAV/-PAS and one case of BYDV-MAV/-PAV. Next, RT-PCR reactions confirmed single BYDV-GAV infection and the common presence of BYDV-SGV. To the best of our knowledge, in 2020 the viruses were not a big threat to cereal crops in Poland.
The shipment of cut flowers from Colombia and Ecuador to the United States, the biggest importer of this product in the world, has doubled in the last 20 years. One of the main constraints in cut roses production is the gray mold disease caused by the fungus Botrytis cinerea, which can destroy the flowers, in the crop, during storage and/or shipping. Since the resistance of the fungus to conventional fungicides has been increasing, as well as the health effects in rose growers, alternative approaches for controlling the disease are needed. The effect of UV-C light on the gray mold development in cut roses was studied. Irradiation with 2,160; 1,080 and 540 J ⋅ m–2 UV-C, every 24 h for 5 days in a humid chamber, did not harm the roses. Instead, as seen by image analysis, a highly significant reduction of the area of the lesions by the disease and of the fungus germination was obtained at 1,080 J ⋅ m–2. The addition of a 4-h dark period to the irradiation did not improve the effect of UV-C on the disease. The results of this work potentiate the use of UV-C light in the agro-industry as a low-cost and non-invasive alternative method to control diseases. They also reflect the application of optical approaches as image analysis in the evaluation of important agricultural features.
Species of the genus Salsola belong to the family Chenopodiaceae and are associated with large saline areas in eastern Iran. The aim of the study was to isolate and characterize the endophytic and phytopathogenic fungal communities from non-mycotrophic Salsola species. Sampling was done from different parts of Salsola plants in the Birjand region in 2017 and 2018. Isolation and identification of fungal isolates were done using biological characteristics and ITS region sequences. The pathogenicity of the representative isolates was investigated by cultivating disinfected Salsola incanescens seeds under greenhouse conditions and inoculating seedlings with a fungal spore suspension from 7 day old fungal colonies on PDA media. Based on morphological and molecular data, 27 isolates from 11 fungal species were isolated and identified from Salsola tissues. Alternaria alternata, A. chlamydospora, Aspergillus terreus, Macrophomina phaseolina, Fusarium longipes, Ulocladium atrum, and Talaromyes pinophilus caused root or stem rotting and yellowing leaf of S. incanescens under greenhouse conditions. Aspergillus niger induced S. incanescens crown swelling without any pathogenicity. Clonostachys rosea, F. redolens and F. proliferatum grew as endophytic fungi on S. incanescens roots. This is the first report of phytopathogenic M. phaseolina, F. longipes, T. pinophilus, endophytic F. redolens and A. niger as a swelling agent on S. incanescens.
The aim of this study was to monitor pesticide residues in the blood of agricultural workers (farmers, pesticide dealers, and spraying workers) living in the Dakahlia Governorate, Egypt. Residue analysis revealed that 48, 76, and 84% of the farmers, pesticide dealers, and spraying workers had pesticide residues in their bloods, respectively. Eleven compounds were detected in the blood of examined individuals. According to the World Health Organization (WHO) classification, most of these pesticides (nine pesticides) were in moderately hazardous compounds. Carbofuran, a highlyhazardous compound was the most toxic. The compound with the lowest toxicity was hexytiazox, which is unlikely to pose an acute hazard in normal use. Chlorpyrifos was found in the blood of 38.3% of the study subjects, followed by acetamiprid (11.7%) and profenofos (10.7%), while fenvalerate was the lowest occurring compound (1.3%). Of the collected samples 41.3% was free of pesticide residues, while 58.7% of the samples was contaminated. Furthermore, the amounts of all detected pesticides were below the no observable adverse effect levels (NOAEL). Also, 38.7% of the samples had only one pesticide, while 8% of them contained residues of two pesticides, and 5.3% contained more than two compounds. The worker’s age did not affect the accumulations of pesticide residues in their bodies. However, there was a strong correlation between pesticide residues accumulation and an individual’s exposure time. Therefore, from these results it can be seen that encouraging greater awareness among pesticide users of the need to improve safe usage and handling of pesticides by education, advice, and warning them of the risks involved in the misuse of these poisonous materials is highly recommended.
Plant derived α-amylase inhibitors are proteinaceous molecules that regulate the enzyme activity in plants and also protect plants from insect attack. In the current study, 28 accessions of 19 plant species were screened for their α-amylase inhibitory activity. The durum wheat varieties, Beni Suef-1 and Beni Suef-5, showed strong α-amylase inhibitory activity and were subjected to further purification studies using ammonium sulfate fractionation and DEAE-Sephadex G-25 column. The isolated inhibitors were found to be stable at temperatures below 80°C with maximum activity obtained at 40−50°C. Also, they were stable in a wide pH range (2−12). The ion exchange products of purified α-amylase inhibitors from Beni Suef-1 and Beni Suef-5 varieties showed a molecular weight of 16 and 24 kDa, respectively. The purified α-amylase inhibitors were tested against Tribolium castaneum and Callosobruchus maculatus both in vitro and in vivo. There was linear inhibition of α-amylase activity with increasing inhibitor concentration until saturation was reached. Beni Suef-5 α-amylase inhibitor was more potent against α-amylase with lower IC50 values than Beni Suef-1 α-amylase inhibitor except in the case of T. castaneum larva. Kinetics analysis revealed that Beni Suef-1 and Beni Suef-5 α-amylase inhibitors are non-competitive types of inhibitors with high affinity toward α-amylase of T. castaneum and C. maculatus. Results of the in vivo studies demonstrated that α-amylase inhibitors isolated from durum wheat, Beni Suef-1 and Beni Suef-5 varieties, were very effective in inhibiting the development of T. castaneum and C. maculatus and could be used for future studies in developing insect resistant transgenic plants approaching α-amylase inhibitor genes.
Currently, production of wheat cultivars (Triticum aestivum L.) that show durable field resistance against fungal pathogens is a priority of many breeding programs. This type of resistance involves race-nonspecific mechanisms and can be identified at adult-plant stages. Until now, seven genes (Lr34/Yr18, Lr46/Yr29, Lr67/Yr46, Lr68, Lr75, Lr77 and Lr78) conferring durable types of resistance against multiple fungal pathogens have been identified in the wheat gene pool. In this study we showed a multiplex Polymerase Chain Reaction (multiplex PCR) assay, which was developed for detection of slow rusting resistance genes Lr34, Lr46, Lr68, using molecular markers: csLV34, Xwmc44 and csGS, respectively. Identification of molecular markers was performed on 40 selected wheat genotypes which are the sources of slow rusting genes according to literature reports. Multiplex PCR is an important tool to reduce the time and cost of analysis. This multiplex PCR protocol can be applicable for genotyping processes and marker assisted resistance breeding of wheat.
In the current study the antifungal activity of inorganic reagents was tested against Cryphonectria parasitica in vitro in a mycelial growth inhibition test. Three reagents, each consisting of chloride silver (AgCl) in combination with (1) aluminum oxide − Al2O3, (2) zinc oxide − ZnO, and (3) Al2O3 and titanium dioxide – TiO2, were tested. Significant differences of the tested reagents on the growth of C. parasitica were recorded. The study demonstrated that silver in mixture with ZnO had an antifungal effect and significantly reduced the mycelial growth of C. parasitica in vitro. The mixture of AgCl with the other two combinations of inorganic metal oxides had no inhibition effect on the growth of the pathogen. It was confirmed that ZnO (applied in a single compound test) is responsible for inhibition of C. parasitica mycelium growth. A preliminary in planta assay was performed but statistically significant differences were not recorded in the average increment of canker length.
Obviously, the moment has come in agriculture and forestry when we must decide to gradually abandon (where possible) non-selectively acting chemical insecticides, taking into consideration the overall decrease in the total biomass of insects, especially pollinators, and the increased number of diseases and human deaths directly or indirectly associated with chemical insecticides. Yet with the world facing the rapid growth of human populations, the annual reduction of cultivated areas, and substantial losses from insect pests, most experts believe that no serious alternative to chemical insecticides exists. However, there is definitely room to create more well-tailored chemical insecticides. And there is hope, in the form of effective DNA insecticides able to provide an adequate level of safety for non-target organisms. In this short communication describing experiments carried out on the larvae of Ceroplastes japonicus Green (feeding on Ilex aquifolium Linnaeus), we show for the first time the enormous potential for the use of DNA insecticides in the control of soft scale insects and how they could replace non-selective organophosphate insecticides.
The genus Cnephasia is represented by more than 70 species of insects worldwide, including serious pests of agricultural plants, mainly cereals. Since members of this genus are frequently very similar externally, species determination based on morphotaxonomy is time-consuming and difficult, especially for non-taxonomists. Hence, it could possibly be replaced by molecular biology approaches. A short nucleotide sequence of mitochondrial cytochrome oxidase I (mtCOI) constitutes a commonly used molecular marker for phylogenetic analyses identification. The aim of this work was molecular species determination of leaf rollers, collected in Poland, that on the basis of external features were hardly distinguishable. We amplified, sequenced and phylogenetically studied the fragment of the mtCOI gene for each individual. Comparative analyses showed the highest nucleotide similarity to C. genitalana, C. longana, C. pasiuana, C. asseclana and C. stephensiana, which was also confirmed by phylogeny. Obtained results showed genetic variation of the analyzed fragment of the mtCOI gene between analyzed Cnephasia spp. found in Poland that can be helpful in proper species determination. This in turn, may be essential for successful biological control and pest monitoring in crop cultivation.
The efficacy of the fungus Lecanicillium lecanii and two bacteria, Bacillus thuringiensis and Streptomyces avermitilis against the two-spotted spider mite Tetranychus urticae Koch and side effects on its predatory mite Phytoseiulus persimilis A.-H. was studied under laboratory conditions. Both S. avermitilis and B. thuringiensis based biopesticides resulted in maximum mortality rates of 90–100% and 91–99% for spider mite adults and larvae, respectively. The mortality of spider mite larvae under fungus L. lecanii treatment was around 60%. These bacteria and fungus also had toxic effects against P. persimilis on the same day of applying insecticides and releasing the predatory mite. The release of predatory mites one day post-treatment of plants with L. lecanii and 7 days post-treatment with B. thuringiensis or S. avermitilis did not negatively affect the survival of predators released. These findings support the potential use of entomopathogenic fungi and bacteria in combination with predatory mites in spider mite biocontrol.
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