Plant biotechnology in agriculture

Novel Approaches for Sustainable Horticultural Crop Production: Advances and Prospects

Reduction of plant growth, yield and quality due to diverse environmental constrains along with climate change significantly limit the sustainable production of horticultural crops. In this review, we highlight the prospective impacts that are positive challenges for the application of beneficial microbial endophytes, nanomaterials (NMs), exogenous phytohormones strigolactones (SLs) and new breeding techniques (CRISPR), as well as controlled environment horticulture (CEH) using artificial light in sustainable production of horticultural crops. The benefits of such applications are often evaluated by measuring their impact on the metabolic, morphological and biochemical parameters of a variety of cultures, which typically results in higher yields with efficient use of resources when applied in greenhouse or field conditions. Endophytic microbes that promote plant growth play a key role in the adapting of plants to habitat, thereby improving their yield and prolonging their protection from biotic and abiotic stresses. Focusing on quality control, we considered the effects of the applications of microbial endophytes, a novel class of phytohormones SLs, as well as NMs and CEH using artificial light on horticultural commodities. In addition, the genomic editing of plants using CRISPR, including its role in modulating gene expression/transcription factors in improving crop production and tolerance, was also reviewed.

Advances in heterocycles as DNA intercalating cancer drugs

The insertion of a molecule between the bases of DNA is known as intercalation. A molecule is able to interact with DNA in different ways. DNA intercalators are generally aromatic, planar, and polycyclic. In chemotherapeutic treatment, to suppress DNA replication in cancer cells, intercalators are used. In this article, we discuss the anticancer activity of 10 intensively studied DNA intercalators as drugs. The list includes proflavine, ethidium bromide, doxorubicin, dactinomycin, bleomycin, epirubicin, mitoxantrone, ellipticine, elinafide, and echinomycin. Considerable structural diversities are seen in these molecules. Besides, some examples of the metallo-intercalators are presented at the end of the chapter. These molecules have other crucial properties that are also useful in the treatment of cancers. The successes and limitations of these molecules are also presented.

Hepatitis B core-based virus-like particles: A platform for vaccine development in plants

Virus-like particles (VLPs) are a class of structures formed by the self-assembly of viral capsid protein subunits and contain no infective viral genetic material. The Hepatitis B core (HBc) antigen is capable of assembling into VLPs that can elicit strong immune responses and has been licensed as a commercial vaccine against Hepatitis B. The HBc VLPs have also been employed as a platform for the presentation of foreign epitopes to the immune system and have been used to develop vaccines against, for example, influenza A and Foot-and-mouth disease. Plant expression systems are rapid, scalable and safe, and are capable of providing correct post-translational modifications and reducing upstream production costs. The production of HBc-based virus-like particles in plants would thus greatly increase the efficiency of vaccine production. This review investigates the application of plant-based HBc VLP as a platform for vaccine production.

Soybean genetic transformation: A valuable tool for the functional study of genes and the production of agronomically improved plants

Transgenic plants represent an invaluable tool for molecular, genetic, biochemical and physiological studies by gene overexpression or silencing, transposon-based mutagenesis, protein sub-cellular localization and/or promoter characterization as well as a breakthrough for breeding programs, allowing the production of novel and genetically diverse genotypes. However, the stable transformation of soybean cannot yet be considered to be routine because it depends on the ability to combine efficient transformation and regeneration techniques. Two methods have been used with relative success to produce completely and stably transformed plants: particle bombardment and the Agrobacterium tumefaciens system. In addition, transformation by Agrobacterium rhizogenes has been used as a powerful tool for functional studies. Most available information on gene function is based on heterologous expression systems. However, as the activity of many promoters or proteins frequently depends on specific interactions that only occur in homologous backgrounds, a final confirmation based on a homologous expression system is desirable. With respect to soybean biotech improvement, transgenic lines with agronomical, nutritional and pharmaceutical traits have been obtained, including herbicide-tolerant soybeans, which represented the principal biotech crop in 2011, occupying 47% of the global biotech area.

Recent advances in plant transformation

Plant genetic engineering has become one of the most important molecular tools in the modern molecular breeding of crops. Over the last decade, significant progress has been made in the development of new and efficient transformation methods in plants. Despite a variety of available DNA delivery methods, Agrobacterium- and biolistic-mediated transformation remain the two predominantly employed approaches. In particular, progress in Agrobacterium-mediated transformation of cereals and other recalcitrant dicot species has been quite remarkable. In the meantime, other transgenic-enabling technologies have emerged, including generation of marker-free transgenics, gene targeting, and chromosomal engineering. Although transformation of some plant species or elite germplasm remains a challenge, further advancement in transformation technology is expected because the mechanisms of governing the regeneration and transformation processes are now better understood and are being creatively applied to designing improved transformation methods or to developing new enabling technologies.

Production of recombinant single chain antibodies (scFv) in vegetatively reproductive Kalanchoe pinnata by in planta transformation

We developed an asexual reproductive plant, Kalanchoe pinnata, as a new bioreactor for plant-based molecular farming using a newly developed transformation method. Leaf crenate margins were pin-pricked to infect the plant with the Agrobacterium strain LBA4404 and vacuum infiltration was also applied to introduce the target gene into the plants. Subsequently, the young mother leaf produced new clones at the leaf crenate margins without the need for time- and labor-consuming tissue culture procedures. The average transformation rates were approximately 77 and 84% for pin-prickling and vacuum-infiltration methods, respectively. To functionally characterize an introduced target protein, a nucleic acid hydrolyzing recombinant 3D8 scFv was selected and the plant based 3D8 scFv proteins were purified and analyzed. Based on abzyme analysis, the purified protein expressed with this system had catalytic activity and exhibited all of properties of the protein produced in an E. coli system. This result suggested that vegetatively reproductive K. pinnata can be a novel and potent bioreactor for bio-pharmaceutical proteins.

Bioactive beads-mediated transformation of rice with large DNA fragments containing Aegilops tauschii genes

Transformation with large DNA molecules enables multiple genes to be introduced into plants simultaneously to produce transgenic plants with complex phenotypes. In this study, a large DNA fragment (ca. 100 kb) containing a set of Aegilops tauschii hardness genes was introduced into rice plants using a novel transformation method, called bioactive beads-mediated transformation. Nine transgenic rice plants were obtained and the presence of transgenes in the rice genome was confirmed by PCR and FISH analyses. The results suggested that multiple transgenes were successfully integrated in all transgenic plants. The expression of one of the transgenes, puroindoline b, was confirmed at the mRNA and protein levels in the T(2) generation. Our study clearly demonstrates that the bioactive bead method is capable of producing transgenic rice plants carrying large DNA fragments. This method will facilitate the production of useful transgenic plants by introducing multiple genes simultaneously.

[Metabolic control of seed germination]

We have used proteomics to better characterize germination and early seedling vigor in sugarbeet. Our strategy includes (1) construction of proteome reference maps for dry and germinating seeds of a high-vigor reference seed lot; (2) investigation of the specific tissue accumulation of proteins (root, cotyledon, perisperm); (3) investigation of changes in protein expression profiles detected in the reference seed lot subjected to different vigor-modifying treatments, e.g. aging and/or priming. More than 1 000 sugarbeet seed proteins have been identified by LC/MS-MS mass spectrometry (albumins, globulins and glutelins have been analyzed separately). Due to the conservation of protein sequences and the quality of MS sequencing (more than 10 000 peptide sequences have been obtained), the success rate of protein identification was on the average of 80%. This is to our knowledge the best detailed proteome analysis ever carried out in seeds. The data allowed us to build a detailed metabolic chart of the sugarbeet seed, generating new insights into the molecular mechanisms determining the development of a new seedling. Also, the proteome of a seed-storage tissue as the perisperm is described for the first time.