Agrobacterium-Mediated Transformation for Insect-Resistant Plants
01 Jan 2019-pp 275-283
TL;DR: Bacillus thuringiensis (Bt) is considered as gram-positive, aerobic, spore-forming, naturally occurring facultative soilborne bacterial pathogen and has been used for natural insect control and produces a parasporal, persistent insecticidal protein crystals (ICPs).
Abstract: Bacillus thuringiensis (Bt) is considered as gram-positive, aerobic, spore-forming, naturally occurring facultative soilborne bacterial pathogen and has been used for natural insect control. It produces a parasporal, persistent insecticidal protein crystals (ICPs). These ICPs are toxic in nature for a class of lepidopterans, dipterans, and coleopterans. That toxic protein differs, depending on the subspecies of Bt producing it. The most prevalent ICPs are the Cry (crystal) protein, and the other is Cty (cytolytic) protein produced by some Bacillus thuringiensis stains. The Cry proteins, in general were cleaved by proteolytic enzymes on intake to produce active toxins which results in osmotic imbalance, lysis of epithelial cells, and finally death due to starvation, whereas Cty proteins release vegetative insecticidal proteins (VIPs) which lead to membrane disruptions, midgut lysis, and paralysis in lepidopterans pests. The use of ICPs as a pesticide or insecticide over chemicals is more beneficial as there is less amount of environmental pollution and harmful chemical residues leaching into the soil and water bodies. It is also target specific and acts on specific class of pests and at the same time harmless to birds, fish, and mammals whose acidic gut conditions negate the bacteria’s effect.
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01 Jan 2023
TL;DR: A review of microbial genes-based transgenic plants for tolerance against abiotic stresses, improved nutrients, and disease resistance can be found in this paper , where the expression of foreign genes induce changes at the biochemical, physio-chemical, anatomical, morphological, and physiological levels, which ultimately improve stresses tolerance and crop production.
Abstract: Microbial genes from fungi, virus, actinomycete, and bacteria have been widely explored for the improvement of crop plants. Here we review microbial genes-based transgenic plants for tolerance against abiotic stresses, improved nutrients, and disease resistance. Genetic engineering involves the transfer of desirable genes of foreign origin to plants. The expression of foreign genes induce changes at the biochemical, physio-chemical, anatomical, morphological, and physiological levels, which ultimately improve stresses tolerance and crop production. Foreign genes of microbial origin are delivered to the plant species by methods including Agrobacterium transformation, floral dip transformation, polyethylene glycol/CaCl2-mediated transformation, viral vectors, and the biolistic method. The efficiency of these methods depend on plant type, variety/cultivar, organ, cloning method, and gene size.
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TL;DR: It is now clear that Agrobacterium is capable of transferring DNA to monocotyledons if tissues containing ‘competent’ cells are infected, which will allow the genetic improvement of diverse varieties of rice, as well as studies of many aspects of the molecular biology of rice.
Abstract: Agrobacterium tumefaciens has been routinely utilized in gene transfer to dicotyledonous plants, but monocotyledonous plants including important cereals were thought to be recalcitrant to this technology as they were outside the host range of crown gall. Various challenges to infect monocotyledons including rice with Agrobacterium had been made in many laboratories, but the results were not conclusive until recently. Efficient transformation protocols mediated by Agrobacterium were reported for rice in 1994 and 1996. A key point in the protocols was the fact that tissues consisting of actively dividing, embryonic cells, such as immature embryos and calli induced from scutella, were co-cultivated with Agrobacterium in the presence of acetosyringonc, which is a potent inducer of the virulence genes. It is now clear that Agrobacterium is capable of transferring DNA to monocotyledons if tissues containing ‘competent’ cells are infected. The studies of transformation of rice suggested that numerous factors including genotype of plants, types and ages of tissues inoculated, kind of vectors, strains of Agrobacterium,selection marker genes and selective agents, and various conditions of tissue culture, are of critical importance. Advantages of the Agrobacterium-mediated transformation in rice, like on dicotyledons, include the transfer of pieces of DNA with defined ends with minimal rearrangements, the transfer of relatively large segments of DNA, the integration of small numbers of copies of genes into plant chromosomes, and high quality and fertility of transgenic plants. Delivery of foreign DNA to rice plants via A. tumefaciens is a routine technique in a growing number of laboratories. This technique will allow the genetic improvement of diverse varieties of rice, as well as studies of many aspects of the molecular biology of rice.
513 citations
TL;DR: An improved protocol for Agrobacterium-mediated transformation of rice that permitted the regeneration of transgenic plants from callus in only two months is described.
Abstract: An improved protocol forAgrobacterium-mediated transformation of rice is described. The procedure permitted the regeneration of transgenic plants from callus in only two months.
383 citations
TL;DR: A reproducible system has been developed for the production of transgenic plants in indica rice using Agrobacterium-mediated gene transfer and inclusion of acetosyringone in the Agrobacteria suspension and co-culture media proved to be indispensable for successful transformation.
Abstract: A reproducible system has been developed for the production of transgenic plants in indica rice using Agrobacterium-mediated gene transfer. Three-week-old scutella calli served as an excellent starting material. These were infected with an Agrobacterium tumefaciens strain EHA101 carrying a plasmid pIG121Hm containing genes for β-glucuronidase (GUS) and hygromycin resistnace (HygR). Hygromycin (50 mg/l) was used as a selectable agent. Inclusion of acetosyringone (50μM) in the Agrobacterium suspension and co-culture media proved to be indispensable for successful transformation. Transformation efficiency of Basmati 370 was 22% which was as high as reported in japonica rice and dicots. A large number of morphologically normal, fertile transgenic plants were obtained. Integration of foreign genes into the genome of transgenic plants was confirmed by Southern blot analysis. GUS and HygR genes were inherited and expressed in R1 progeny. Mendelian segregation was observed in some R1 progeny.
336 citations
TL;DR: The characteristics which would be desirable in an ideal transgenic technology are analysed, which include being environmentally benign, relatively inexpensive to develop, with a potentially wide spectrum of activity (although targetable at pests and not bene"cials), generated by a #exible technology that allows any insect site to be targeted and readily adaptable so that alternatives can be produced as required.
316 citations
TL;DR: Using this method, transgenic rice plants can be obtained in about 2–3 months with a transformation frequency of 30–50%, both in easily cultured varieties and recalcitrant elite japonica rice.
Abstract: Agrobacterium-mediated transformation of rice is an important method that has been widely adopted by many laboratories. However, because current approaches rely on culture systems, routine protocols have been established only in japonica rice, especially those varieties with higher regeneration potential. Some very efficient methods have been developed for japonica varieties that enable high-throughput functional analysis in rice; however, many elite japonica, and most indica, varieties are difficult to regenerate, leading to low transformation efficiencies. Much effort has been devoted to improving transformation efficiency for all rice genotypes. Here, we describe an Agrobacterium-mediated rice transformation method that is applicable to easily cultured varieties in addition to elite japonica varieties that are more difficult to culture. Using this method, transgenic rice plants can be obtained in about 2–3 months with a transformation frequency of 30–50%, both in easily cultured varieties and recalcitrant elite japonica rice.
294 citations