Bacillus Species: Excellent Biocontrol Agents against Tomato Diseases.

Tomatoes encounter many pathogens, such as fungi and bacteria, which reduce the yield and quality of plants and lead to large losses in production. The application of plant protection products (PPPs) is still an important and most effective measure to control plant diseases. However, the use of chemicals in agriculture contributes to environmental pollution and biodiversity loss, and it can also threaten non-target living organisms. Biological control is a widely accessible, environmentally safe, and cost-efficient alternative for the prevention and suppression of plant diseases. Bacillus species with antimicrobial and plant growth-promoting effects are most frequently used as biocontrol agents to increase the resilience of agricultural production against biotic stresses. The present review discusses the antagonistic mechanisms and the biocontrol potential of Bacillus spp. against tomato diseases caused by different pathogens. The main mechanisms of Bacillus spp. include the production of antimicrobial compounds (antibiotics, extracellular enzymes, siderophores, and volatile compounds), competition for nutrients and space, and induced systemic resistance (ISR). Although Bacillus-based PPPs have been developed and commercialised worldwide for various crops and pathogens, the efficiency issues are still subject to debate. Additionally, a combined strategy for controlling tomato diseases based on Bacillus spp. and other available methods (conventional or natural-based) is a promising research field.

Genetic Diversity of Pectobacterium spp. on Potato in Serbia.

Pectobacterium is a diverse genus which comprises of multiple destructive bacterial species which cause soft rot/blackleg/wilt disease complex in a wide variety of crops by employing high levels of virulence factors. During the 2018, 2019 and 2020 potato growing seasons, numerous outbreaks of bacterial wilt, stem blackleg and tuber soft rot were recorded, and symptomatic plant samples from ten localities in the Province of Vojvodina (Serbia) were collected and analysed. Bacterial soft-rot pathogens were detected in 63 samples using genus and species-specific primers. Through 16S rRNA Sanger sequencing of 19 representative isolates, the identity of P. brasiliense (73.7%), P. punjabense (15.8%), and P. carotovorum (10.5%) species were revealed. To further validate the identification, genotypic profiling of Pectobacterium strains using rep-PCR (ERIC, BOX, REP) was conducted for 25 selected isolates and the phylogenetic assessment based on four selected housekeeping genes (gyrA, recA, rpoA, and rpoS). Physiological and biochemical properties were analysed using basic microbiological tests and VITEK® 2 GN card, and pathogenicity was confirmed on cv. VR808 and cv. Desiree potato tubers and plants. This study confirmed the distinctiveness of the newly described P. punjabense in Serbia as well as the high diversity of Pectobacterium brasiliense and Pectobacterium carotovorum species in Serbia.

Bio-Priming of Soybean with Bradyrhizobium japonicum and Bacillus megaterium: Strategy to Improve Seed Germination and the Initial Seedling Growth.

Bio-priming is a new technique of seed treatment that improves seed germination, vigor, crop growth and yield. The objective of this study was to evaluate the effectiveness of Bradyrhizobium japonicum (commercial strains) and Bacillus megaterium (newly isolated strains) as a single inoculant and co-inoculant during seed bio-priming to improve seed germination and initial seedling growth of two soybean cultivars. The treated seeds were subjected to germination test (GT), cold test (CT) and accelerated aging test (AAT). B. megaterium significantly improved all parameters in GT and CT; final germination, shoot length, root length, root dry weight, and seedling vigor index in AAT, as compared to control. In addition, co-inoculation significantly increased all parameters except shoot dry weight in GT; all parameters in CT; germination energy, shoot length, root length, and seedling vigor index in AAT, in comparison to the control. Moreover, Br. japonicum significantly improved the germination energy, shoot length, shoot dry weight, root dry weight, and seedling vigor index in GT; all parameters in CT; shoot length, root length, and seedling vigor index in AAT, compared with non-primed seeds. Thus, B. megaterium strains could be used in soybean bio-priming as a potential single inoculant and co-inoculant, following proper field evaluation.

Ionic liquids as potentially new antifungal agents against Alternaria species.

The fungal genus Alternaria Nees 1816 includes the most prevalent pathogenic species that can cause crop diseases such as blight, black spot, and dark leaf spot. In accordance with the aim of developing modern sustainable approaches in agriculture for the replacement of synthetic and toxic substances with environmentally friendly alternatives, the objective of this study was to examine the in vitro antifungal activities of 18 newly synthesized ionic liquids (ILs) against three Alternaria strains: A. padwickii, A. dauci and A. linicola. The antifungal activities of the ILs were estimated via a microdilution method to establish minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) values. The results confirmed that 17 of the 18 ILs showed strain specificity, including good antifungal activity toward Alternaria strains, with MIC and MFC values in the range of 0.04 to 0.43 mol dm-3. The strongest antifungal effects toward all analyzed Alternaria strains were displayed by the compounds with long alkyl chains: [omim][Cl] (MIC/MFC: 0.042 mol dm-3), [dmim][Cl] (MIC/MFC: 0.043 mol dm-3), [ddmim][Cl] (MIC/MFC: 0.053 mol dm-3), [ddTSC][Br] (MIC/MFC: 0.053 mol dm-3), and [Allyl-mim][Cl] (MIC/MFC: 0.054 mol dm-3). The introduction of oxygen as a hydroxyl group resulted in less-pronounced toxicity towards Alternaria compared to the introduction of an ether group, while the contribution of the hydroxyl group was shown to be a more determining factor than the prolongation of the side-chain, resulting in overall fungicidal activity decrease. Our results indicate the possibility that the most effective ILs ([Allyl-mim][Cl], [omim][Cl], [dmim][Cl], [ddmim][Cl], [bTSC][Br], [hTSC][Br], [oTSC][Br], [dTSC][Br], and [ddTSC][Br]) could be applied to the control of plant diseases caused by Alternaria species, based on their potential as an environmentally friendly crop protection approach. Since salts based on TSC cations are significantly cheaper to synthesize, stable under mild conditions, and environmentally friendly after degradation, thiosemicarbazidium-based ILs can be a suitable replacement for commercially available imidazolium ILs.

Threshold Level and Traceability of Roundup Ready® Soybeans in Tofu Production.

The aim of this study is to assess DNA degradation, DNA amplification, and GMO quantity during tofu production. Soybean seeds were spiked with Roundup Ready® soybeans (RRS) at 0.9, 2, 3 and 5% (by mass), to assess the level of RSS that would be of practical interest for threshold labelling. Real-time polymerase chain reaction (PCR) was more effective than conventional PCR in the analysis of raw soymilk, okara, boiled soymilk and tofu. The negative effect of grinding and mechanical manipulation was obvious in the okara sample prepared with 3 and 5% RRS, where GMO content was reduced to (2.28±0.23) and (2.74±0.26) %, respectively. However, heating at 100 °C for 10 min did not cause significant degradation of DNA in all samples. The content of RRS in the final product, tofu, was reduced tenfold during processing, ranging from 0.07 to 0.46%, which was below the labelling threshold level. The results are discussed in terms of global harmonization of GMO standards, which could have the positive effect on the trade of lightly processed foodstuffs such as tofu, especially regarding the labelling policies.

Detection of genetically modified soybean in crude soybean oil.

In order to detect presence and quantity of Roundup Ready (RR) soybean in crude oil extracted from soybean seed with a different percentage of GMO seed two extraction methods were used, CTAB and DNeasy Plant Mini Kit. The amplifications of lectin gene, used to check the presence of soybean DNA, were not achieved in all CTAB extracts of DNA, while commercial kit gave satisfactory results. Comparing actual and estimated GMO content between two extraction methods, root mean square deviation for kit is 0.208 and for CTAB is 2.127, clearly demonstrated superiority of kit over CTAB extraction. The results of quantification evidently showed that if the oil samples originate from soybean seed with varying percentage of RR, it is possible to monitor the GMO content at the first stage of processing crude oil.