Development of a protocol for genetic transformation of Malus spp

A protocol to produce transgenic shoots of Malus X domestica cv Greensleaves was optimized using two gene constructs previously used to create parthenocarpic tomato, Ino-IaaM and DefH9-IaaM. The aim was to obtain sufficient nº of transgenic shoots for in vitro multiplication, transfer to soil, grafting and testing for parthenocarpy in the next years. We investigated the effects of two modifications of a previous published protocol: 1) co-transformation with an Agrobacterium containing “VIP” genes in the gene construct and 2) two different hormones or hormone combinations. More shoot regeneration was obtained with a combination of three hormones (BA:NAA:TDZ) during co-cultivation instead of IBA and no co-transformation was performed using the VIP gene. For the DefH9-IaaM transgene, 21.04% regeneration was achieved for this treatment instead of 8.95% achieved with “IBA treatment” and 4.42% with the Agrobacterium co-transformation treatment. More shoot regeneration occurred with the combination of three hormones (BA:NAA:TDZ) instead of with only IBA and no co-transformation was performed using VIP gene. Experiments using Ino-IaaM confirmed the results shown for the DefH9-IaaM transgene. The regenerated shoots were multiplied in selective media containing kanamycin and roots were obtained.

Field evaluation of transgenic hybrid poplars with desirable wood properties and enhanced growth for biofuel production by bicistronic expression of PdGA20ox1 and PtrMYB3 in wood-forming tissue

Background To create an ideotype woody bioenergy crop with desirable growth and biomass properties, we utilized the viral 2A-meidated bicistronic expression strategy to express both PtrMYB3 (MYB46 ortholog of Populus trichocarpa, a master regulator of secondary wall biosynthesis) and PdGA20ox1 (a GA20-oxidase from Pinus densiflora that produces gibberellins) in wood-forming tissue (i.e., developing xylem). Results Transgenic Arabidopsis plants expressing the gene construct DX15::PdGA20ox1-2A-PtrMYB3 showed a significant increase in both stem fresh weight (threefold) and secondary wall thickening (1.27-fold) relative to wild-type (WT) plants. Transgenic poplars harboring the same gene construct grown in a greenhouse for 60 days had a stem fresh weight up to 2.6-fold greater than that of WT plants. In a living modified organism (LMO) field test conducted for 3 months of active growing season, the stem height and diameter growth of the transgenic poplars were 1.7- and 1.6-fold higher than those of WT plants, respectively, with minimal adverse growth defects. Although no significant changes in secondary wall thickening of the stem tissue of the transgenic poplars were observed, cellulose content was increased up to 14.4 wt% compared to WT, resulting in improved saccharification efficiency of the transgenic poplars. Moreover, enhanced woody biomass production by the transgenic poplars was further validated by re-planting in the same LMO field for additional two growing seasons. Conclusions Taken together, these results show considerably enhanced wood formation of our transgenic poplars, with improved wood quality for biofuel production.

Strategy for Designing the Synthetic Gene Encoding Human papillomavirus Major Capsid L1 Protein for Heterologous Expression in Escherichia coli System

DNA is widely used to construct heterologously expressed genes. The adaptation of the codons to the host organism is necessary in order to ensure sufficient production of proteins. The GC content, codon identity and the mRNA from the translation site are also important in the design of the gene construct. This study performed a strategy for the design of synthetic gene encoding HPV52 L1 protein and several analyses at the genetic level to optimize its protein expression in the Escherichia coli BL21(DE3) host. The determination of the codon optimization was performed by collecting 75 HPV52 L1 protein sequences in the NCBI database. Furthermore, all the sequences were analyzed using multiple global alignments by Clustal Omega web server. Once the model was determined, codon optimization was performed using OPTIMIZER and the web server of the IDT codon optimization tool based on the E. Coli B. The generated open reading frame (ORF) sequence was analyzed using Restriction mapper web server to choose the restriction site for facilitating the cloning stage, which is adjusted for pJExpress414 expression vector. To maximize the protein expression level, the mRNA secondary structure analysis around the ribosome binding site (rbs) was performed. A slight modification at the 5’-terminal end waa carried out in order to get more accessible rbs and increasing mRNA folding free energy. Finally, the construction of the synthetic gene was confirmed to ensure that no mutation occurs in the protein and to calculate its Codon Adaptation Index (CAI) and GC content. The above strategy, which leads to a good ORF sequence with the value of the free mRNA folding energy around rbs, is -5.5 kcal / mol, CAI = 0.787 and GC content 49.5%. This result is much better than its original gene. This result is much better compared to its native gene. Theoretically it is possible that this synthetic gene construct generates a high level protein expression in E. coli BL21 (DE3) under the regulation of the T7 promoter.

Strategy to design and functionally analyze an miR targeted reporter gene construct using In planta assay

Plants, upon exposure to environmental stress, express sophisticated and co-ordinated responses to reprogram interconnected defense networks and metabolic pathways. These responses are governed by intricate molecular and biochemical signal transduction processes, which act in harmony to determine tolerance and sensitivity at a holistic level. Modern studies in plant stress biology include identification of key genes that influence stress tolerance and the verification of gene functions using knockout mutants or over-expression lines. Abiotic stresses induce aberrant expression of many miRNAs, suggesting that miRNAs could be a new target for genetically improving plant stress tolerance. MicroRNAs (miRNAs), 21-24 nts in length, are an extensive class of endogenous small RNA molecules that provide a fascinating option for engineering tolerance to environmental stress by serving as non-protein coding switches of both desirable and undesirable gene expressions. During abiotic stress, miRNAs function by regulatingthe stress inducing networks like signalling components and a variety of transcription factors (TFs) that leads to cleavage of the target genes. It is important to identify the expression domains of miRs and their targets to understand how the spatio-temporal regulations are co-ordinated under stress. In this project, we aim to design reporter gene construct containing the target site of selected miR. We have selected pCAMBIA1302 vector with the aim to insert the target site before the ATG of GFP gene such that the coding frame remains intact. Later, the functionality of the designed construct can be checked by expressing the constructs In planta using Agroinfiltration and the technology is expected to greatly favour in molecular pharming.

Standardisation of an Agroinfiltration Protocol for Eggplant Fruits and Proving its Usefulness by Over-expressing the SmHQT Gene

Eggplant is a fruit vegetable of family Solanaceae, and eggplant fruits are of different shape and sizes that render them as an ideal system for metabolic engineering. Here, we have developed an agroinfiltration protocol for the transient expression of a gene in the eggplant fruit using GUS bearing; pCAMBIA1304 vector. Thereafter, to prove the effectiveness of the developed protocol, we have used the eggplant hydroxycinnamoyl CoA-quinate transferase (SmHQT), which is the central enzyme studied to increase the chlorogenic acid content, in a gene construct with the specific promoter in a plant transformation vector (pBIN19). Also, in our cassette, we also co-expressed the P19 protein of Tomato bushy stunt virus (native promoter) to overexpress the protein. Overall, using the protocol, the chlorogenic content was increased by more than two folds in the transgenic tissues.

Expression of Hemagglutinin-Neuraminidase (HN) and Fusion (F) Epitopes of Newcastle Disease Virus (NDV) in Chlamydomonas reinhardtii

Owing to their unique characteristics which combines the properties of both prokaryotes and eukaryotes, microalgae have emerged as an ideal platform for heterologous production of recombinant proteins including subunit vaccines. In an attempt to develop recombinant vaccine against Newcastle Disease, an agrobacterium-mediated genetic transformation was carried out to express a chimeric gene construct including Hemagglutinin-Neuraminidase (HN) and Fusion (F) epitopes of Newcastle Disease Virus (NDV) in Chlamydomonas reinhardtii. Four tandem repeat of HN epitope with 96bp length followed by three tandem repeat of F epitope of NDV with 153bp length were used. Microalgal cells (Chlamydomonas reinhardtii) were co-cultivated with Agrobacterium tumefaciens cells harboring foreign gene construct and then transferred to selection medium. Single colonies representing putative transformation events were screened in selection medium enriched with kanamycin. PCR assay confirmed integration of F-HN sequence in microalgal nuclei. RT-PCR assay showed that the F-HN sequence was expressed in transformed colonies. Finally, translation of the foreign gene was confirmed by protein dot blotting, western blot and Elisa assay. The results of this experiment may contain both research and practical implications.