“…The cry genes of Bacillus thuringiensis and synthetic cry genes are transferred to crops for insect or pest resistance. A synthetic cry2AX1 gene (NCBI accession GQ332539.1) made with plant-preferred codons and expressed in rice and cotton showed significant protection against different types of lepidopteran insects [111][112][113]. However, designing of two kinds of codon optimised cry genes, one for monocot and another for dicot plants are also in vogue to improve the chances for getting events with desirable level of transgene expression.…”
Section: Applications Of Codon Usage Studiesmentioning
Codon usage bias is the preferential or non-random use of synonymous codons, a ubiquitous phenomenon observed in bacteria, plants and animals. Different species have consistent and characteristic codon biases. Codon bias varies not only with species, family or group within kingdom, but also between the genes within an organism. Codon usage bias has evolved through mutation, natural selection, and genetic drift in various organisms. Genome composition, GC content, expression level and length of genes, position and context of codons in the genes, recombination rates, mRNA folding, and tRNA abundance and interactions are some factors influencing codon bias. The factors shaping codon bias may also be involved in evolution of the universal genetic code. Codon-usage bias is critical factor determining gene expression and cellular function by influencing diverse processes such as RNA processing, protein translation and protein folding. Codon usage bias reflects the origin, mutation patterns and evolution of the species or genes. Investigations of codon bias patterns in genomes can reveal phylogenetic relationships between organisms, horizontal gene transfers, molecular evolution of genes and identify selective forces that drive their evolution. Most important application of codon bias analysis is in the design of transgenes, to increase gene expression levels through codon optimization, for development of transgenic crops. The review gives an overview of deviations of genetic code, factors influencing codon usage or bias, codon usage bias of nuclear and organellar genes, computational methods to determine codon usage and the significance as well as applications of codon usage analysis in biological research, with emphasis on plants.
“…The cry genes of Bacillus thuringiensis and synthetic cry genes are transferred to crops for insect or pest resistance. A synthetic cry2AX1 gene (NCBI accession GQ332539.1) made with plant-preferred codons and expressed in rice and cotton showed significant protection against different types of lepidopteran insects [111][112][113]. However, designing of two kinds of codon optimised cry genes, one for monocot and another for dicot plants are also in vogue to improve the chances for getting events with desirable level of transgene expression.…”
Section: Applications Of Codon Usage Studiesmentioning
Codon usage bias is the preferential or non-random use of synonymous codons, a ubiquitous phenomenon observed in bacteria, plants and animals. Different species have consistent and characteristic codon biases. Codon bias varies not only with species, family or group within kingdom, but also between the genes within an organism. Codon usage bias has evolved through mutation, natural selection, and genetic drift in various organisms. Genome composition, GC content, expression level and length of genes, position and context of codons in the genes, recombination rates, mRNA folding, and tRNA abundance and interactions are some factors influencing codon bias. The factors shaping codon bias may also be involved in evolution of the universal genetic code. Codon-usage bias is critical factor determining gene expression and cellular function by influencing diverse processes such as RNA processing, protein translation and protein folding. Codon usage bias reflects the origin, mutation patterns and evolution of the species or genes. Investigations of codon bias patterns in genomes can reveal phylogenetic relationships between organisms, horizontal gene transfers, molecular evolution of genes and identify selective forces that drive their evolution. Most important application of codon bias analysis is in the design of transgenes, to increase gene expression levels through codon optimization, for development of transgenic crops. The review gives an overview of deviations of genetic code, factors influencing codon usage or bias, codon usage bias of nuclear and organellar genes, computational methods to determine codon usage and the significance as well as applications of codon usage analysis in biological research, with emphasis on plants.
“…The limited variability within the genetic resources along with their cross incompatibility with pigeonpea cultivars make the crop improvement through conventional breeding an arduous task. Genetic transformation, on the other hand, has enabled transfer of desirable transgenes and development of transgenic plants that need to be analyzed through various methods for selecting a transgenic event(s) with stable gene inheritance and expression over generations, imperative for successful M Singh et al deployment at field level (Jadhav et al 2020). The present study was thus conducted on molecular characterization of T 1 , T 2 and T 3 plants generated through selfing of cry1Ab carrying T 0 transformants developed earlier in our laboratory through Agrobacterium mediated in planta transformation (Singh et al 2021).…”
Development of transgenic crops with stable gene inheritance and expression over generations is important for effective deployment at field level.In present study, T 1 plants of pigeonpea cultivars AL15 and AL201 were evaluated for the presence and expression of cry1Ab gene and protection against Maruca pod borer. Cry1Ab protein in transgene carrying T 1 plants ranged from 0.72 to 0.87 µg g-1 flower tissue. In vitro insect bioassay demonstrated up to 49.17 and 53.80% loss in larval body weight after four days of infesting T 1 transgenic flowers and pods, respectively. Further, no adults emerged from the pupae of larvae fed on transgenic plants 15-537 and 201-344. All T 2 progeny plants of 15-537 exhibited cry1Ab presence; likewise, all T 3 progeny plants derived from homozygous T 2 plant (15-537-5) displayed presence and expression of transgene, thus establishing stable transgene integration in T 1 plants, followed by its stable inheritance and expression in T 2 and T 3 generations.
“…This strategy of in planta transformation has been utilized for the successful transformation of different crop species ( Kesiraju and Sreevathsa, 2017 ); including fiber crops like cotton ( Karthik et al, 2020a ; Kesiraju et al, 2020 ) and flax ( Karthik et al, 2020b ). Moreover, development of transgenic cotton resistant to H. armigera has been a pertinent endeavour by various research groups ( Tabashnik et al, 2002 ; Wu et al, 2003 ; Kurtz et al, 2007 ; Anilkumar et al, 2008 ; Singh et al, 2016 ; Han et al, 2017 ; Bajwa et al, 2020 ; Jadhav et al, 2020 ; Katta et al, 2020 ).…”
Section: Resultsmentioning
confidence: 99%
“…Genetic engineering for the development of insect resistant plants has been considered as a revolutionary contribution in agricultural biotechnology. Transgenesis in economically important crop plants like cotton ( Chen et al, 2017 ; Ribeiro et al, 2017 ; Siddiqui et al, 2019 ; Bajwa et al, 2020 ; Jadhav et al, 2020 ; Katta et al, 2020 ); soybean ( Marques et al, 2017 ; Moghaieb et al, 2019 ; Qin et al, 2019 ; Bacalhau et al, 2020 ); maize ( Moscardini et al, 2020 ); pigeon pea ( Ghosh et al, 2017 ; Singh et al, 2018 ; Ramkumar et al, 2020 ); chick pea ( Das et al, 2017 ); cow pea ( Bett et al, 2017 ; Addae et al, 2020 ; Kumar et al, 2021 ); sweet potato ( Zhong et al, 2019 ); jute ( Majumder et al, 2020 ); castor ( Muddanuru et al, 2019 ), etc., by the introgression of insecticidal proteins encoding genes from Bacillus thuringiensis ( Bt ) resulted in plants with improved ability to mitigate the pest load. Reduced topical applications of chemical pesticides and increased agricultural productivity have been major achievements of transgenic technology ( Fleming et al, 2018 ) in crop improvement.…”
Cotton is a commercial crop of global importance. The major threat challenging the productivity in cotton has been the lepidopteron insect pest Helicoverpa armigera or cotton bollworm which voraciously feeds on various plant parts. Biotechnological interventions to manage this herbivore have been a universally inevitable option. The advent of plant genetic engineering and exploitation of Bacillus thuringiensis (Bt) insecticidal crystal proteins (ICPs) marked the beginning of plant protection in cotton through transgenic technology. Despite phenomenal success and widespread acceptance, the fear of resistance development in insects has been a perennial concern. To address this issue, alternate strategies like introgression of a combination of cry protein genes and protein-engineered chimeric toxin genes came into practice. The utility of chimeric toxins produced by domain swapping, rearrangement of domains, and other strategies aid in toxins emerging with broad spectrum efficacy that facilitate the avoidance of resistance in insects toward cry toxins. The present study demonstrates the utility of two Bt ICPs, cry1AcF (produced by domain swapping) and cry2Aa (produced by codon modification) in transgenic cotton for the mitigation of H. armigera. Transgenics were developed in cotton cv. Pusa 8–6 by the exploitation of an apical meristem-targeted in planta transformation protocol. Stringent trait efficacy-based selective screening of T1 and T2 generation transgenic plants enabled the identification of plants resistant to H. armigera upon deliberate challenging. Evaluation of shortlisted events in T3 generation identified a total of nine superior transgenic events with both the genes (six with cry1AcF and three with cry2Aa). The transgenic plants depicted 80–100% larval mortality of H. armigera and 10–30% leaf damage. Molecular characterization of the shortlisted transgenics demonstrated stable integration, inheritance and expression of transgenes. The study is the first of its kind to utilise a non-tissue culture-based transformation strategy for the development of stable transgenics in cotton harbouring two novel genes, cry1AcF and cry2Aa for insect resistance. The identified transgenic events can be potential options toward the exploitation of unique cry genes for the management of the polyphagous insect pest H. armigera.
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