Agrobacterium tumefaciens-mediated plant transformation is the most dominant technique for the transformation of plants. It is used to transform monocotyledonous and dicotyledonous plants. A. tumefaciens apply for stable and transient transformation, random and targeted integration of foreign genes, as well as genome editing of plants. The Advantages of this method include cheapness, uncomplicated operation, high reproducibility, a low copy number of integrated transgenes, and the possibility of transferring larger DNA fragments. Engineered endonucleases such as CRISPR/Cas9 systems, TALENs, and ZFNs can be delivered with this method. Nowadays, Agrobacterium-mediated transformation is used for the Knock in, Knock down, and Knock out of genes. The transformation effectiveness of this method is not always desirable. Researchers applied various strategies to improve the effectiveness of this method. Here, a general overview of the characteristics and mechanism of gene transfer with Agrobacterium is presented. Advantages, updated data on the factors involved in optimizing this method, and other useful materials that lead to maximum exploitation as well as overcoming obstacles of this method are discussed. Moreover, the application of this method in the generation of genetically edited plants is stated. This review can help researchers to establish a rapid and highly effective Agrobacterium-mediated transformation protocol for any plant species.

BACKGROUND: Hairy roots are a plant-tissue culture raised by Rhizobium rhizogenes infection (formerly known as Agrobacterium rhizogenes). Nowadays, these roots have been gaining more space in biotechnology due to their benefits for the recombinant expression of valuables proteins; it includes simplified downstream processing, protein rhizosecretion, and scalability in bioreactors. However, due to methodological inconsistency among reports, the tissue platform is still a promising technology.
RESULTS: In the current paper, we propose the first step to overcome this issue through a systematic review of studies that employ Nicotiana hairy roots for recombinant expression. We conducted a qualitative synthesis of 36 out of 387 publications initially selected. Following the PRISMA procedure, all papers were assessed for exclusion and inclusion criteria. Multiple points of root culture were explored, including transformation methods, root growth curve, external additives, and scale-up with bioreactors to determine which approaches performed best and what is still required to achieve a robust protocol.
CONCLUSIONS: The information presented here may help researchers who want to work with hairy roots in their laboratories trace a successful path to appraisal the literature status.

Chlamydomonas reinhardtii is a model organism with three sequenced genomes capable of genetic transformation. C. reinhardtii has the advantages of being low cost, non-toxic, and having a post-translational modification system that ensures the recombinant proteins have the same activity as natural proteins, thus making it a great platform for application in molecular biology and other fields. In this review, we summarize the existing methods for nuclear transformation of C. reinhardtii, genes for selection, examples of foreign protein expression, and factors affecting transformation efficiency, to provide insights into effective strategies for the nuclear transformation of C. reinhardtii.

Agrobacterium rhizogenes, along with A. tumefaciens, has been used to affect genetic transformation in plants for many years. Detailed studies conducted in the past have uncovered the basic mechanism of foreign gene transfer and the implication of Ri/Ti plasmids in this process. A number of reviews exist describing the usage of binary vectors with A. tumefaciens, but no comprehensive account of the numerous binary vectors employed with A. rhizogenes and their successful applications has been published till date. In this review, we recollect a brief history of development of Ri-plasmid/Ri-T-DNA based binary vectors systems and their successful implementation with A. rhizogenes for different applications. The modification of native Ri plasmid to introduce foreign genes followed by development of binary vector using Ri plasmid and how it facilitated rapid and feasible genetic manipulation, earlier impossible with native Ri plasmid, have been discussed. An important milestone was the development of inducible plant expressing promoter systems which made expression of toxic genes in plant systems possible. The successful application of binary vectors in conjunction with A. rhizogenes in gene silencing and genome editing studies which are relatively newer developments, demonstrating the amenability and adaptability of hairy roots systems to make possible studying previously intractable research areas have been summarized in the present review.

UNASSIGNED: This review provides an in-depth and comprehensive overview of the in vitro culture of Tylophora species, which have medicinal properties. Tylophora indica (Burm. f.) Merr. is a climbing perennial vine with medicinal properties. The tissue culture and genetic transformation of T. indica, which has been extensively studied, is reviewed. Micropropagation using nodal explants has been reported in 25 % of all publications. Leaf explants from field-grown plants has been the explant of choice of independent research groups, which reported direct and callus-mediated organogenesis as well as callus-mediated somatic embryogenesis. Protoplast-mediated regeneration and callus-mediated shoot organogenesis has also been reported from stem explants, and to a lesser degree from root explants of micropropagated plants in vitro. Recent studies that used HPLC confirmed the potential of micropropagated plants to synthesize the major T. indica alkaloid tylophorine prior to and after transfer to field conditions. The genetic integrity of callus-regenerated plants was confirmed by RAPD in a few reports. Tissue culture is an essential base for genetic transformation studies. Hairy roots and transgenic T. indica plants have been shown to accumulate tylophorine suggesting that in vitro biology and transgenic methods are viable ways of clonally producing valuable germplasm and mass producing compounds of commercial value. Further studies that investigate the factors affecting the biosynthesis of Tylophora alkaloids and other secondary metabolites need to be conducted using non-transformed as well as transformed cell and organ cultures.

Cytokines are a family of signaling polypeptides involved in cell-cell interactions in the process of the immune response, as well as in the regulation of a number of normal physiological functions. Cytokines are used in medicine for the treatment of cancer, immune disorders, viral infections, and other socially significant diseases, but the extent of their use is limited by the high production cost of the active agent. The development of this area of pharmacology is associated with the success of genetic engineering, which allows the production of significant amounts of protein by transgenic organisms. The review discusses the latest advances in the production of various cytokines with the use of genetically modified plants.

Peanut (Arachis hypogaea L.) is a major species of the family, Leguminosae, and economically important not only for vegetable oil but as a source of proteins, minerals and vitamins. It is widely grown in the semi-arid tropics and plays a role in the world agricultural economy. Peanut production and productivity is constrained by several biotic (insect pests and diseases) and abiotic (drought, salinity, water logging and temperature aberrations) stresses, as a result of which crop experiences serious economic losses. Genetic engineering techniques such as Agrobacterium tumefaciens and DNA-bombardment-mediated transformation are used as powerful tools to complement conventional breeding and expedite peanut improvement by the introduction of agronomically useful traits in high-yield background. Resistance to several fungal, virus and insect pest have been achieved through variety of approaches ranging from gene coding for cell wall component, pathogenesis-related proteins, oxalate oxidase, bacterial chloroperoxidase, coat proteins, RNA interference, crystal proteins etc. To develop transgenic plants withstanding major abiotic stresses, genes coding transcription factors for drought and salinity, cytokinin biosynthesis, nucleic acid processing, ion antiporter and human antiapoptotic have been used. Moreover, peanut has also been used in vaccine production for the control of several animal diseases. In addition to above, this study also presents a comprehensive account on the influence of some important factors on peanut genetic engineering. Future research thrusts not only suggest the use of different approaches for higher expression of transgene(s) but also provide a way forward for the improvement of crops.

Plants provide an immense reservoir of natural secondary metabolites. Secondary metabolites and those involved enzymes accumulate in various compartments in specific plant tissues. The biosynthesis of diverse groups of secondary metabolites is often complicated, tightly controlled via network interconnections, metabolite levels, metabolite channeling and multi-enzyme complexes, and so on. Secondary metabolite profiles could be genetically altered by two strategies, i.e. single gene modification and multiple gene modification; which thus has opened a feasible and prospective platform for secondary chemicals production in plant.

The past 30 years have witnessed a series of systematic biotechnological advances made in pomegranate. These encompass optimization and establishment of in vitro culture techniques including micropropagation, somatic embryogenesis, synthetic seed production, plant regeneration via callus-mediated shoot organogenesis, adventitious shoot regeneration, anther culture, tetraploid induction and genetic transformation. This review attempts to provide a comprehensive account on the tissue culture-mediated biotechnological interventions made in pomegranate aimed at complementing conventional programmes for improvement of this nutraceutically important fruit crop.

Microalgae represent the \'best of both worlds\', combining the high growth rate and ease of cultivation of microorganisms with the ability to perform post-transcriptional and post-translational modifications of plants. The development of economically viable microalgal expression systems is, however, hindered by low recombinant protein yields. Although there are still many obstacles to overcome before microalgae become standard expression systems, considerable progress has been made in recent years in regards to elucidating the causes for these low yields and in the development of strategies to improve them. Transgenes have successfully been expressed in both nuclear and chloroplast microalgal genomes, although at economically viable levels only in the latter. The present review describes recent progress in genetic manipulation of microalgae, outlines strategies to increase protein yields and presents some interesting avenues of research that remain to be explored.