Plant-Expressed Receptor Binding Domain of the SARS-CoV-2 Spike Protein Elicits Humoral Immunity in Mice

The current 15-month coronavirus disease-19 (COVID-19) pandemic caused by SARS-CoV-2 has accounted for 3.77 million deaths and enormous worldwide social and economic losses. A high volume of vaccine production is urgently required to eliminate COVID-19. Inexpensive and robust production platforms will improve the distribution of vaccines to resource-limited countries. Plant species offer such platforms, particularly through the production of recombinant proteins to serve as immunogens. To achieve this goal, here we expressed the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein in the glycoengineered-tobacco plant Nicotiana benthamiana to provide a candidate subunit vaccine. This recombinant RBD elicited humoral immunity in mice via induction of highly neutralizing antibodies. These findings provide a strong foundation to further advance the development of plant-expressed RBD antigens for use as an effective, safe, and inexpensive SARS-CoV-2 vaccine. Moreover, our study further highlights the utility of plant species for vaccine development.

Optimized Scale-Invariant Hog Descriptors for Tobacco Plant Detection

The histogram of gradient (HOG) descriptor is being employed in this research work to demonstrate the technique of scale variant to identify the plant in surveillance videos. In few scenarios, the discrepancies in the histogram of gradient descriptors along with scale as well as variation in illumination are considered as one of the major hindrances. This research work introduces a unique SIO-HOG descriptor that is approximated to be scale-invariant. With the help of the footage that is captured from the tobacco plant identification process, the system can integrate adoptive bin selections as well as sample resizing. Further, this research work explores the impact of a PCA transform that is based on the process of feature selection on the performance of overall recognition and thereby considering finite scale range, adoptive orientation binning in non-overlapping descriptors, as well as finite scale range are all essential for a high detection rate. The feature vector of HOG over a complete search window is computationally intensive. However, suitable frameworks for classification can be developed by maintaining a precise range of attributes with finite Euclidean distance. Experimental results prove that the proposed approach for detecting tobacco from other weeds has resulted in an improved detection rate. And finally, the robustness of the complete plant detection system was evaluated on a video sequence with different non-linearity's that is quite common in a real-world environment and its performance metrics are evaluated

Tobacco Leaf Curl Puer Virus: a Novel Monopartite Begomovirus Infecting Nicotiana Tabacum in China

Begomoviruses (family Geminiviridae) cause serious diseases in many economic crops and weeds globally. This study characterized a begomovirus isolated from a tobacco plant with leaf curl in Puer, Yunnan Province, China. Analysis of the viral genome obtained from a diseased Nicotiana tabacum plant showed a novel monopartite begomovirus. The DNA-A-like sequence (2741 nt) has the typical Old World monopartite begomovirus genome organization, sharing the highest nucleotide sequence identity (81.2%) with that of Tomato yellow leaf curl Vietnam virus (TYLCVV). According to the current International Committee on Taxonomy of Viruses (ICTV )taxonomic criteria, this is a new species of begomovirus for which the name “Tobacco leaf curl Puer virus” is proposed.

Analysis of MeEf1A6 Gene Promoter Activity with In-vitro and In-vivo using Transient and Stable Expression Techniques in Tobacco Plant (Nicotiana tabacum)

The promoter is a part of the gene that functions in carrying out the gene expression, and its work activity becomes a matter of concern to ensure that expression works effectively. MeEF1A6 (Manihot esculenta Elongation Factor 1 Alfa - 6) is a promoter derived from cassava plants (Manihot esculenta). In previous studies, the MeEF1A6 promoter was successfully isolated, introduced, and characterized into the pBI121 plasmid, replacing the CaMV35S promoter. This study aims to analyze the activity of MeEF1A6 promoters in-vivo and in-vitro by using transient and transgenic techniques in tobacco plants. The pBI121 plasmid containing the MeEF1A6 promoter was introduced into Agrobacterium tumefaciens strain AGL1 and LBA4404. The promoter's work was then analyzed by the result of introducing it into the tobacco plant using the transient and stable transformation. The whole part of explants was used for transient study and tested in a minimum of two biological replicates. Sixty sheets of explant leaves that have been cut were used for stable transformation. The promoter work analysis was carried out with the GUS gene expression that integrated with the promoter with histochemical GUS assay. The transient produced a blue color in the roots, stems, and leaves on the whole repetition. The transverse incision in the stem shows the blue color on the epidermis and procambium tissue. Stable transformation using AGL1 as vector produced 43 shoots from 40 calli. A total of 43 shoots were selected with antibiotics and produced 27 plantlets that were successfully grown. Some plantlets are then reacted with x-gluc as histochemical GUS assay substrat and produced a blue color in the explants, indicating that the MeEF1A6 promoter has been successfully introduced. The results indicate that the MeEF1A6 promoter could work on plant tissue in roots, stems, leaves, and tissues that connect meristems such as procambium in tobacco plants. This reinforces the suspicion that the MeEF1A6 promoter performs work constitutionally as a constitutive promoter.

Variation in Manduca sexta Pollination-Related Floral Traits and Reproduction in a Wild Tobacco Plant

Most flowering plants depend on animal pollination for successful sexual reproduction. Floral signals such as color, shape, and odor are crucial in establishing this (often mutualistic) interaction. Plant and pollinator phenotypes can vary temporally but also spatially, thus creating mosaic-like patterns of local adaptations. Here, we investigated natural variation in floral morphology, flower volatile emission, and phenology in four accessions of a self-compatible wild tobacco, Nicotiana attenuata, to assess how these traits match the sensory perception of a known pollinator, the hawkmoth Manduca sexta. These accessions differ in floral traits and also in their habitat altitudes. Based on habitat temperatures, the accession occurring at the highest altitude (California) is less likely to be visited by M. sexta, while the others (Arizona, Utah 1, and Utah 2) are known to receive M. sexta pollinations. The accessions varied significantly in flower morphologies, volatile emissions, flower opening, and phenology, traits likely important for M. sexta perception and floral handling. In wind tunnel assays, we assessed the seed set of emasculated flowers after M. sexta visitation and of natural selfed and hand-pollinated selfed flowers. After moth visitations, plants of two accessions (Arizona and Utah 2) produced more capsules than the other two, consistent with predictions that accessions co-occurring with M. sexta would benefit more from the pollination services of this moth. We quantified flower and capsule production in four accessions in a glasshouse assay without pollinators to assess the potential for self-pollination. The two Utah accessions set significantly more seeds after pollen supplementation compared with those of autonomous selfing flowers, suggesting a greater opportunistic benefit from efficient pollinators than the other two. Moreover, emasculated flowers of the accession with the most exposed stigma (Utah 2) produced the greatest seed set after M. sexta visitation. This study reveals intraspecific variation in pollination syndromes that illuminate the potential of a plant species to adapt to local pollinator communities, changing environments, and altered pollination networks.

Extraction and Determination of Nicotine in Tobacco from Selected Local Cigarettes Brands in Iraq

Tobacco smoke contains more than 3,800 different compounds, where all could harm the exposed humans to different degrees. Among them, nicotine (3-(1-methyl-2-pyrrolidinyl) pyridine) is considered the most toxic compound. In many countries, tobacco smoking is considered a severe health hazard and a significant factor in death and several common diseases. Because of that, knowing the toxicity of nicotine is important to help understand tobacco-induced human diseases and identify the potential risks associated with the therapeutic use of nicotine as an aid in smoking cessation. Thereby, estimating the nicotine amount is very crucial in tobacco production. As this work aims to extract and determine nicotine, which is the highest toxic component in tobacco plant leaves, several methods were carried out to extract the nicotine. All extracting methods were based on water extraction as a polar solvent and the other non-polar solvents. Water shows a limited extraction activity for nicotine from tobacco leaves. Since nicotine is a dibasic compound, an alkaline solution (40% NaOH) was used to extract nicotine from tobacco leaves for the selected samples. Further, solvent extraction by non-polar solvents was conducted to extract nicotine from the alkaline solution and prepare it for the spectrometric analysis. FT-IR and UV analysis show that the oily substance, which was extracted from tobacco leaves, is nicotine. Results were confirmed by microscopic examination for the extracted nicotine after the addition of mercuric chloride, where flowery shape crystals of nicotine liganded with mercuric chloride complex were formed.