China
Africa
Explore chapters and articles related to this topic
Agrobacterium and Plant Genetic Engineering
Published in Yoshikatsu Murooka, Tadayuki Imanaka, Recombinant Microbes for Industrial and Agricultural Applications, 2020
Masami Sekine, Atsuhiko Shinmyo
Since the T-DNA-located genes are not required for this transferring process, DNA that is inserted between the T-DNA borders can be efficiently transferred to the plant genome. Many studies have been carried out using this system to analyze the molecular mechanism involved in the control of gene expression [7]. The ease of a plant’s regeneration, which is based on its totipotency, could enable the production of numerous transgenic plants. Therefore, studies in plants will produce an important contribution to understand the molecular basis of plant development and differentiation. An alternative approach has been attempted to identify or to isolate a gene using T-DNA as an insertional element, since insertion of T-DNA can alter the expression of the neighboring gene, which might cause a screenable phenotype [8,9].
Production of VNPs, VLPs, and Chimeras
Published in Nicole F Steinmetz, Marianne Manchester, Viral Nanoparticles, 2019
Nicole F Steinmetz, Marianne Manchester
This method exploits the plant bacterium Agrobacterium tumefaciens, which causes crown-gall disease in plants. Agrobacterium tumefaciens can invade wounded plant cells and transform the cells resulting in tumor growth. The bacteria contain a tumor-inducing plasmid, the Ti-plasmid. During infection, a segment of the Ti-plasmid is transferred into the plant cell; this segment is referred to as transfer or T-DNA. The T-DNA is incorporated into the plant genome by recombination, resulting in transient expression of the T-DNA genes. The T-DNA is flanked by 25-bp direct repeats, termed the left and right borders, that mediate the recombination event. Transfer of the T-DNA is induced by activation of the so-called virulence (vir) genes on the Ti-plasmid. Phenolic compounds, mainly acetosyringone, that are produced and released from wounded plant cells initiate expression of the vir genes. The T-DNA encodes for growth hormones, which stimulate tumor formation, as well as for unnatural amino acids such as nopaline, mannopine, and octopine, which serve as an energy source for the bacterium. The reader is referred to the following textbooks for more information on the biology of Agrobacterium and its use as an expression system: Molecular Biology of the Cell (Alberts et al., 2008) and Agrobacterium: From Biology to Biotechnology (Tzvi & Vitaly, 2008).
Plant Biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
The Agrobacterium-mediated technique involves the natural gene transfer system in the bacterial plant pathogens of the genus Agrobacterium. In nature, Agrobacterium tumefaciens and Agrobacterium rhizogenes are the causative agents of the crown gall and the hairy root diseases, respectively. The utility of Agrobacterium as a gene transfer system was first recognized when it was demonstrated that these plant diseases were produced because of the transfer and integration of genes from the bacteria into the genome of the plant. Both Agrobacterium species carry a large plasmid (small circular DNA molecule) called Ti in A. tumefaciens and Ri in A. rhizogenes. A segment of this plasmid designated T-(for transfer) DNA is transmitted by this organism into individual plant cells, usually within wounded tissue. The T-DNA segment penetrates the plant cell nucleus and integrates randomly into the genome where it is stably incorporated and inherited like any other plant gene in a predictable, dominant Mendelian fashion. Expression of the natural genes on the T-DNA results in the synthesis of gene products that direct the observed morphological changes such as tumor or hairy root formation. In genetic engineering, the tumor-inducing genes within the T-DNA, which cause the plant disease, are removed and replaced by foreign genes. These genes are then stably integrated into the genome of the plant after infection with the altered strain of Agrobacterium, just like the natural T-DNA. Because all tumor-inducing genes are removed, the gene transfer does not induce any disease symptoms. This reliable method of gene transfer is well suited for plants that are susceptible to infection by Agrobacterium. Unfortunately, many species, especially economically important legumes and monocotyledons such as cereals, do not respond positively to Agrobacterium-mediated transformation (Figure 6.6).
Establishment and elicitation of transgenic root culture of Plantago lanceolata and evaluation of its anti-bacterial and cytotoxicity activity
Published in Preparative Biochemistry & Biotechnology, 2021
Samaneh Rahamouz-Haghighi, Khadijeh Bagheri, Ali Sharafi, Hossein Danafar
One of the plant diseases is hairy root (HR) which is caused by Agrobacterium rhizogenes.[1] HR occurs when root loci (rol) genes harbored by the root inducing plasmid (Ri) of A. rhizogenes integrate into the nuclear genome of the infected plant cells. It is believed that numerous factors impact the frequency of A. rhizogenes mediated transformation in host plants like bacterial strains, Acetosyringone as well as salt concentration in co-cultivation media.[2] The high growth rate of transformed root cultures is very attractive for the industrial production of secondary metabolites.[3] In a study, Sudha et al. mentioned that the effects of endogenous hormones and bacterial strains reacted to the rol gene products might lead to tumors.[4] The T-DNA regions, chromosomal virulence (chv) and virulence (vir) genes, are essential for DNA transference from bacteria to the host plant cells. The rol A, B, C and D genes are supported by TL-DNA that separates the Ri-plasmid of A. rhizogenes from the Ti-plasmid in A. tumefaciens.[5,6] The rolB induced HR and plays a key role in the secretion of active auxin performed by indoxyl-β-oxidase activity.[7] On the other hand, rolA, rolC, rolD, and other open reading frames act together in order to promote root induction.[8]