Expression analysis of human β-secretase in transgenic tomato fruits

Current Advances of Plant-Based Vaccines for Neurodegenerative Diseases

Neurodegenerative diseases (NDDs) are characterized by the progressive degeneration and/or loss of neurons belonging to the central nervous system, and represent one of the major global health issues. Therefore, a number of immunotherapeutic approaches targeting the non-functional or toxic proteins that induce neurodegeneration in NDDs have been designed in the last decades. In this context, due to unprecedented advances in genetic engineering techniques and molecular farming technology, pioneering plant-based immunogenic antigen expression systems have been developed aiming to offer reliable alternatives to deal with important NDDs, including Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Diverse reports have evidenced that plant-made vaccines trigger significant immune responses in model animals, supported by the production of antibodies against the aberrant proteins expressed in the aforementioned NDDs. Moreover, these immunogenic tools have various advantages that make them a viable alternative for preventing and treating NDDs, such as high scalability, no risk of contamination with human pathogens, cold chain free production, and lower production costs. Hence, this article presents an overview of the current progress on plant-manufactured vaccines for NDDs and discusses its future prospects.

Identification of essential element determining fruit-specific transcriptional activity in the tomato HISTIDINE DECARBOXYLASE A gene promoter

In SlHDC-A promoter, SlHDC-A core-ES is an essential region for fruit-specific expression and interacts with GATA, HSF and AP1. Triplication of essential region was proposed as a minimal fruit-specific promoter. In plant biotechnology, fruit-specific promoter is an important tool for the improvement and utilization of tomato fruit. To expand our understanding on fruit-specific expression, it is necessary to determine the promoter region involved in fruit-specific transcriptional activity and transcriptional regulations of the promoter. In previous study, we isolated a fruit-specific SlHDC-A core promoter specifically expressed during tomato ripening stages. In this study, we identified SlHDC-A promoter region (SlHDC-A core-ES) that is essential for fruit-specific expression of the SlHDC-A. To understand the molecular mechanisms of fruit-specific expression of the SlHDC-A promoter, we first identified the putative transcription factor binding elements in the SlHDC-A core promoter region and corresponding putative transcription factors which are highly expressed during fruit maturation. Yeast one hybrid analysis confirmed that GATA, HSF, and AP1 interact with the SlHDC-A core-ES promoter region. Further transactivation analysis revealed that expression of the three transcription factors significantly activated expression of a reporter gene driven by SlHDC-A core-ES promoter. These results suggest that GATA, HSF, and AP1 are involved in the fruit-specific expression of SlHDC-A promoter. Furthermore, the synthetic promoter composed of three tandem repeats of SlHDC-A core-ES showed relatively higher activity than the constitutive 35S promoter in the transgenic tomato fruits at the orange stage. Taken together, we propose a new synthetic promoter that is specifically expressed during fruit ripening stage.

Functional characterization of a strong promoter of the early light-inducible protein gene from tomato

The tomato ELIP gene promoter is mainly active in the ripening fruit. Considering its high activity, the promoter could be used for molecular breeding of plants in the future. The ability to obtain new varieties of transgenic plants with economically valuable traits relies on a high level of target gene expression, which is largely controlled by a gene promoter. Hence, research aimed at finding and characterizing new tissue-specific promoters that direct gene expression in specific plant tissues or at certain developmental stages has become the most important field of plant biotechnology. Here, we cloned and characterized the promoter of the early light-inducible protein (ELIP) gene from tomato (Solanum lycopersicum cv. Yalf). ELIPs are produced in the presence of light and putatively function in the chloroplast-to-chromoplast conversion, playing a photorepairing role in the photosynthetic system. Analysis of the promoter sequence revealed multiple cis-acting elements related to light responsiveness, and other motifs involved in plant hormone response and circadian control. To determine the functionality of the promoter, seven 5'-deletion variants were fused with the β-glucuronidase (GUS) reporter gene and introduced into tomato. Histochemical analysis of transgenic tomato plants revealed different levels of GUS activity in most analyzed tissues, depending on the promoter fragment used. The intensity of staining was considerably higher in ripening fruits than in unripe and non-fruit tissues. Quantitative analysis indicated that the level of GUS activity with the longest (full-length) version of the ELIP promoter in ripened fruits was comparable to that in plants expressing the constitutive CaMV35S promoter. Further, the location of both negative and positive regulatory motifs was identified. The described ELIP promoter is a potential tool for various applications in plant biotechnology.

In vitro regeneration of eight cultivars of Brassica oleracea var. capitata

Eight cultivars of Brassica oleracea var. capitata and two types of explant (hypocotyl and cotyledon) were tested for their potential to regenerate under in vitro conditions. Hypocotyl and cotyledon explants from 10-d-old seedlings were subcultured onto different callus induction media based on Murashige and Skoog (MS) basal medium supplemented with 1% sucrose and different concentrations and combinations of plant growth regulators. Hypocotyl explants were found to be more suitable for callus induction and organogenesis than cotyledon explants for all cultivars tested. In terms of regeneration, the cv. 'Amager' was significantly more responsive than the other cultivars tested and produced the highest number of shoots/buds per explant. Moreover, among five types of media tested, MS + 8.88 μM 6-benzyloaminopurine (BAP) + 0.53 μM α-naphthylacetic acid (NAA) was most effective for shoot regeneration. Rooting was achieved within 10-15 d on all the rooting media, but MS medium containing 5.37 μM NAA produced the maximum number of strong and healthy roots. Plantlets (95%) were subsequently established in the greenhouse, and no phenotypic variations were observed among regenerated plants. This plant regeneration protocol could be suitable for a wide range of cabbage cultivars.

Plant-based vaccines for Alzheimer's disease: an overview

Plants are considered advantageous platforms for biomanufacturing recombinant vaccines. This constitutes a field of intensive research and some plant-derived vaccines are expected to be marketed in the near future. In particular, plant-based production of immunogens targeting molecules with implications on the pathology of Alzheimer's has been explored over the last decade. These efforts involve targeting amyloid beta and β-secretase with several immunogen configurations that have been evaluated in test animals. The results of these developments are analyzed in this review. Perspectives on the topic are identified, such as exploring additional antigen configurations and adjuvants in order to improve immunization schemes, characterizing in detail the elicited immune responses, and immunological considerations in the achievement of therapeutic humoral responses via mucosal immunization. Safety concerns related to these therapies will also be discussed.

Production of pharmaceutical proteins in solanaceae food crops

The benefits of increased safety and cost-effectiveness make vegetable crops appropriate systems for the production and delivery of pharmaceutical proteins. In particular, Solanaceae edible crops could be inexpensive biofactories for oral vaccines and other pharmaceutical proteins that can be ingested as minimally processed extracts or as partially purified products. The field of crop plant biotechnology is advancing rapidly due to novel developments in genetic and genomic tools being made available today for the scientific community. In this review, we briefly summarize data now available regarding genomic resources for the Solanaceae family. In addition, we describe novel strategies developed for the expression of foreign proteins in vegetable crops and the utilization of these techniques to manufacture pharmaceutical proteins.