Micro (nano) plastics uptake, toxicity and detoxification in plants: Challenges and prospects.

Plastic pollution has emerged as a global challenge affecting ecosystem health and biodiversity conservation. Terrestrial environments exhibit significantly higher plastic concentrations compared to aquatic systems. Micro/nano plastics (MNPs) have the potential to disrupt soil biology, alter soil properties, and influence soil-borne pathogens and roundworms. However, limited research has explored the presence and impact of MNPs on aquaculture systems. MNPs have been found to inhibit plant and seedling growth and affect gene expression, leading to cytogenotoxicity through increased oxygen radical production. The article discusses the potential phytotoxicity process caused by large-scale microplastics, particularly those unable to penetrate cell pores. It also examines the available data, albeit limited, to assess the potential risks to human health through plant uptake.

Heterologous expression of Arabidopsis SOS3 increases salinity tolerance in Petunia.

BACKGROUND: Salinity stress is one of the most important rising problems worldwide. It significantly reduces plant growth and development, mainly by provoking excessive uptake of ions such as Na+. The Salt Overly Sensitive (SOS) machinery is a well-known signaling pathway that help plants to maintain ion homeostasis by reducing Na+ accumulation in plant cells. Overexpression of key components of this pathway has been reported to increase salinity stress tolerance in some plant species. METHODS AND RESULTS: In this study, SOS3 cDNA isolated from Arabidopsis seedlings was transferred into the Petunia genome by two common plant transformation methods, Agrobacterium and biolistic gun. Transgene integration and expression in putative lines were evaluated by PCR and RT-PCR techniques. In vitro and greenhouse evaluation of transgenic plants for salt tolerance showed that, compared to the wild type, transgenic plants overexpressing AtSOS3 gene exhibit enhanced salt tolerance in response to high NaCl concentrations. CONCLUSIONS: These results not only demonstrate the potential of SOS pathway components to improve salt tolerance in Petunia, but also provide more evidence for functional conservation of the SOS salt tolerance signaling pathway among different plant families.

Identification of differentially expressed genes in salt-tolerant oilseed sunflower (Helianthus annuus L.) genotype by RNA sequencing.

BACKGROUND: Sunflower (Helianthus annuus L.) is widely planted as an oilseed crop worldwide. Salt stress is one of the major abiotic stresses that negatively affect crop growth and productivity. To counter the negative impact of salt stress, plants have developed avoidance and tolerance mechanisms. Developing salt-tolerant genotypes requires understanding the molecular basis of adaptive mechanisms in depth. Although using model plants i.e., Arabidopsis has improved our understanding of salt tolerant mechanisms, the relative impotence and regulation mechanisms vary among plant species due to differences in genetic and metabolic backgrounds. On the other hand, sunflower is a highly polymorphic plant due to its cross-pollinated behavior which provides different salt-tolerant genotypes available for comparative analyses. METHODS AND RESULTS: In order to gain a better view of molecular mechanisms involved in salt tolerance in sunflower, RNA sequencing analysis was realized by evaluating a tolerant genotype (AS5305) with two biological replicates under control and salt stress conditions in a controlled environment. Salinity stress was applied from NaCl resource at the 8-leaf stage and samplings were done at 24 h post salt stress application. Sequencing data were analyzed using tuxedo software suite. Blast2GO software and the KEGG database were used to identify the functional tasks of each of the assembled transcripts. Analysis of genes with robust expression (i.e., with FPKM > 1 in at least one sample) revealed a total of 121 significantly expressed genes between the saline-stressed and control samples. The differential expression of 11 genes was confirmed by real-time PCR. In the following, the cDNA of MYB44 as one of the selected candidate genes involved in salt tolerance was isolated, cloned, and sequenced for comparison. CONCLUSIONS: Overall, the results of the current study may pave the way for the accurate selection of genes involved in salinity to be used in molecular-genetics-assisted breeding programs. In addition, making use of the identified genes may help relieve the damages arising from the salt stress in sunflowers.

Tobacco Plant: A Novel and Promising Heterologous Bioreactor for the Production of Recombinant Bovine Chymosin.

The natural source of chymosin, a key enzyme in the dairy industry, is insufficient for rapidly growing cheese industries. Large-scale production of recombinant proteins in heterologous hosts provides an efficient alternative solution. Here, the codon-optimized synthetic prochymosin gene, which has a CAI index of 0.926, was subcloned from a cloning vector (pUC57-bCYM) into the pBI121 vector, resulting in the construct named pBI121-bCYM. CAI ranges from 0 to 1 and higher CAI improves gene expression in heterologous hosts. The overexpression of the prochymosin gene was under the control of constitutive CaMV 35S promoter and NOS terminator and was transferred into the tobacco via A. tumefaciens strain LBA4404. Explant type, regeneration method, inoculation temperature, cell density (OD600) of Agrobacterium for inoculation, and acetosyringone concentration were leaf explants, direct somatic embryogenesis, 19 °C, 0.1, and 100 µM, respectively. The successful integration and expression of the prochymosin gene, along with the bioactivity of recombinant chymosin, were confirmed by PCR, RT-PCR, and milk coagulation assay, respectively. Overall, this study reports the first successful overexpression of the codon-optimized prochymosin form of the bovine chymosin enzyme in the tobacco via indirect transformation. Production of recombinant bovine chymosin in plants can be an easy-to-scale-up, safe, and inexpensive platform.

Production of functional recombinant roseltide rT1 antimicrobial peptide in tobacco plants.

Plant-derived peptides represent a promising group of natural compounds with broad industrial and pharmaceutical applications. Low-efficiency production level is the major obstacle to the commercial production of such bioactive peptides. Today, recombinant techniques have been developed for fast and cost-effective production of high-quality peptides for various applications in the chemical and food industries. The roseltide rT1 is a plant peptide with different antimicrobial properties and therapeutic applications in the prevention and treatment of inflammatory lung diseases by inhibiting human neutrophil elastases. Here, we report the expression of functional recombinant roseltide rT1 peptide in tobacco plants. Transgenic plants were generated by the Agrobacterium-mediated transformation method followed by molecular analysis of transgenic plants to demonstrate successful integration and expression of recombinant rT1 peptide. Protein extracts of transgenic plants expressing a single-copy rT1 gene showed efficient antimicrobial properties as verified by growth inhibition of different bacterial strains. Our results illustrate that plant-derived recombinant rT1 peptide is a promising alternative for rapid and cost-effective production of this important antimicrobial peptide for application in therapeutic and food industries.

Quinoa: A Promising Crop for Resolving the Bottleneck of Cultivation in Soils Affected by Multiple Environmental Abiotic Stresses.

Quinoa (Chenopodium quinoa Willd.) has gained worldwide recognition for its nutritional values, adaptability to diverse environments, and genetic diversity. This review explores the current understanding of quinoa tolerance to environmental stress, focusing on drought, salinity, heat, heavy metals, and UV-B radiation. Although drought and salinity have been extensively studied, other stress factors remain underexplored. The ever-increasing incidence of abiotic stress, exacerbated by unpredictable weather patterns and climate change, underscores the importance of understanding quinoa's responses to these challenges. Global gene banks safeguard quinoa's genetic diversity, supporting breeding efforts to develop stress-tolerant varieties. Recent advances in genomics and molecular tools offer promising opportunities to improve stress tolerance and increase the yield potential of quinoa. Transcriptomic studies have shed light on the responses of quinoa to drought and salinity, yet further studies are needed to elucidate its resilience to other abiotic stresses. Quinoa's ability to thrive on poor soils and limited water resources makes it a sustainable option for land restoration and food security enterprises. In conclusion, quinoa is a versatile and robust crop with the potential to address food security challenges under environmental constraints.

Transfer and Expression of Native Human Insulin-Like Growth Factor-1 in Tobacco Chloroplasts.

Background: Insulin-like growth factor-1 (IGF-1), in addition to having insulin-like effects, has boosting effects on all cells in human body. Most of the recombinant IGF-1 required for patients suffering from its deficiency is currently produced by bacterial and yeast systems. Plant systems, especially chloroplasts, have many benefits for producing human blood proteins. Production costs are low in these systems, and their side effects are less than other systems. Objectives: In this study, the transfer and expression of mature IGF-1 protein cDNA in tobacco chloroplasts under the control of strong plastid transcription and translation elements was evaluated. Materials and Methods: The biolistic transformation method was used to transfer the IGF-1 gene cloned into the pRB94-IGF1 chloroplast vector. Homoplasmic transplastomic plants were produced through four selection rounds on the selective medium. Transfer of foreign genes to chloroplast genome was confirmed by PCR, Southern blotting and seed progeny test. RT-PCR and SDS-PAGE methods were used to evaluate the expression of IGF-1 gene in transgenic line. Results: A truly transformed line was identified from selected seedlings by PCR method. The seed progeny test of 4th-regeneration-round transgenic plants of this line showed maternal inheritance and homoplasmic level for the selectable marker gene, which confirms the transfer and expression of the marker gene in the chloroplast genome. The Southern blot test also confirmed the transfer of the IGF-1 gene into the chloroplast genome. RT-PCR test showed that IGF-1 gene transcription is performed correctly in transgenic plants. Finally, accumulation of IGF-1 protein in transgenic plants was detected by SDS-PAGE. Conclusions: Successful transfer and expression of the native human IGF-1 gene in tobacco chloroplast genome is reported.

Stable Transformation of the Saintpaulia ionantha by Particle Bombardment.

BACKGROUND: A highly efficient genetic transformation system is essential for a successful genetic manipulation of the African violet (Saintpaulia ionantha Wendl.). OBJECTIVES: Developing a particle bombardment-based genetic transformation system for the African violet. MATERIALS AND METHODS: A local cultivar of the African violet from Guilan province was used for transformation experiments. The pFF19G and pBin61-Ech42 vectors were used for transient and stable transformation experiments, respectively. The PCR and RT-PCR techniques were used to verify transgene presence and transcript levels in candidate transgenic lines, respectively. RESULTS: Using leaf explants as target tissues, we transferred an endochitinase gene cDNA into African violet. Transgenic plants were regenerated on selection medium at a reasonable frequency (in average, one stable transgenic line per shot). Molecular analysis of transgenic plants by PCR and RT-PCR techniques confirmed successful integration and expression of transgene in several independent transgenic lines. CONCLUSIONS: Our results provide an efficient stable transformation system for genetic transformation of African violet.

A leaf-based regeneration and transformation system for maize (Zea mays L.).

Efficient methods for in vitro propagation, regeneration, and transformation of plants are of pivotal importance to both basic and applied research. While being the world's major food crops, cereals are among the most difficult-to-handle plants in tissue culture which severely limits genetic engineering approaches. In maize, immature zygotic embryos provide the predominantly used material for establishing regeneration-competent cell or callus cultures for genetic transformation experiments. The procedures involved are demanding, laborious and time consuming and depend on greenhouse facilities. We have developed a novel tissue culture and plant regeneration system that uses maize leaf tissue and thus is independent of zygotic embryos and greenhouse facilities. We report here: (i) a protocol for the efficient induction of regeneration-competent callus from maize leaves in the dark, (ii) a protocol for inducing highly regenerable callus in the light, and (iii) the use of leaf-derived callus for the generation of stably transformed maize plants.