Introduction To Plant Biotechnology Hs Chawla Pdf Download

This book has been written to meet the needs of students for biotechnology courses at various levels of undergraduate and graduate studies. This book covers all the important aspects of plant tissue culture viz. nutrition media, micropropagation, organ culture, cell suspension culture, haploid culture, protoplast isolation and fusion, secondary metabolite production, somaclonal variation and cryopreservation. For good understanding of recombinant DNA technology, chapters on genetic material, organization of DNA in the genome and basic techniques involved in recombinant DNA technology have been added. Different aspects on rDNA technology covered gene cloning, isolation of plant genes, transposons and gene tagging, in vitro mutagenesis, PCR, molecular markers and marker assisted selection, gene transfer methods, chloroplast and mitochondrion DNA transformation, genomics and bioinformatics. Genomics covers functional and structural genomics, proteomics, metabolomics, sequencing status of different organisms and DNA chip technology. Application of biotechnology has been discussed as transgenics in crop improvement and impact of recombinant DNA technology mainly in relation to biotech crops.

In addition to the importance of cotton, cotton cultivation faces many problems, such as insect pests, weeds and viruses. In the past, insects were controlled by insecticides, but this caused economic loss in the country. Although conventional breeding methodology has made significant progress in the field of cotton improvement, it has limitations to its ability to introduce new alleles (Keshamma et al., 2008). This method still cannot solve the problem of insecticides. To combat losses from insects and pests, insecticides are used excessively every year in developing countries, such as Pakistan. Biotechnology has the potential to create new plants, new genes and new products that are environmentally safe and economically viable (John, 2011). Cotton biotechnology has tremendous commercial implications. It can change the way cotton is cultivated. Cotton was one of the first genetically modified crops to be commercially released (Jones et al., 1996; Wilkins et al., 2005). To obtain high yields, several methods have been used by farmers to minimize the major threats of cotton. For example, weeds have been controlled traditionally by mechanically uprooting methods Weeds compete with crop plants and reduce the yield in both quantity and quality (ICAR, 2009). The implements used for mechanical weed control shear and tear the surface of the soil, resulting in the uprooting of plants. The introduction of herbicide-resistant crops has dramatically changed weed management in crop production systems (Owen, 2001). 5-enolpyruvylshikimic acid-3-phosphate synthase (EPSPS)-encoding bacterial genes transformed into crop plants by the use of stable genetic transformation can confer glyphosate resistance (Fitzgibbon and Braymer, 1990; Padgette et al., 1991).

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Since the introduction of the first genetically modified (GM)/biotech crop plants in the mid-1990s, the agriculture industry has seen a steady increase in the acreage of those crops planted and harvested worldwide each year. In 2014, a record 18 million farmers in 28 countries planted 447 million acres of biotech soybean, maize, cotton, canola, zucchini squash, papaya, alfalfa, poplar, sugar beet, tomato, eggplant, and sweet pepper (James 2014). This represents a more than 100-fold increase in usage between 1996 and 2014. This increase is largely due to the economic, environmental, and productivity benefits derived from their use.

In the U.S., potato annually accounts for $4.2 billion in production value and the crop is grown on just over a million acres (NASS 2015). Potato is an ideal crop for the introduction of traits using biotechnology. In fact, after virus-resistant tobacco (China in 1992) and the FlavrSavr tomato (U.S. in 1994), potato was one of the first crops to be genetically modified; it was grown commercially as NewLeafTM by Monsanto in 1995. Conventional potato breeding as it is practiced worldwide is an inefficient, slow process that has changed little in the past century. Potato requires considerable inputs of nutrients, pesticides, and water to maintain yield, quality, and protection from diseases and insects. Potato breeding efforts have historically focused on yield, fresh market and processing quality, and storability as well as disease resistance. Genetic variation for these traits in commercial cultivars is low, but related wild species contain many traits not found in cultivars and represent an especially rich source of disease resistance and tuber quality genes (Hanneman 1989; Jansky 2000). Efforts have been made to introgress nutritional qualities and resistance to pests and abiotic stresses from wild species into cultivated potato, but popular cultivars have few traits derived from wild germplasm due to their genetic complexity, unpredictable expression in adapted backgrounds, and a desire by industry to limit variability in processing quality (Hirsch et al. 2013). In the U.S., the availability of effective pesticides, fungicides, fumigants, synthetic fertilizers, and irrigation systems has meant that market-driven traits, such as yield, are often given higher priority than biotic and abiotic stress resistances. Combining tuber quality traits desired by consumers and processors with the agronomic performance and disease resistance preferred by farmers remains the most significant challenge in potato breeding. Fortunately, the tremendous amount of genetic diversity in wild and cultivated relatives of potato allows for relatively easy identification, isolation, and introduction of new genes for a specific trait using biotechnology. For example, genes from wild potato relatives can contribute resistance to late blight, Verticillium wilt, potato virus Y, water stress, and cold-induced sweetening (see following discussion). The fact that genes of interest can be derived from wild relatives of potato allows for the production of biotech varieties by inserting potato DNA. This is contrasted with traditional transgenic plants that use DNA derived from bacteria, viruses, or other organisms.

The purpose of this review is to provide readers with an overview of biotech potato including its history, past and potential impact on the industry, targeted traits, consumer perception, and biotech crop safety. Genetic modification of potato to introduce agronomic-, production-, and consumer-oriented traits has led to an opportunity to revolutionize potato breeding and offer an alternative to traditional variety selection methods. We are hopeful that market acceptance of the technology will increase efforts towards the discovery of genes that could be used to improve current varieties. The use of biotechnology will provide a much-needed avenue for the introduction of unique traits present in wild potato relatives, which would typically be difficult or impossible to introduce into cultivated potato using traditional methods.

The introduction of pest resistance into cultivated varieties would reduce pesticide applications. Similarly, manipulation of gene expression that regulates water use efficiency in potato would allow for increased performance under water deficit conditions. Fortunately, collections of wild and cultivated potato germplasm are diverse and many wild species possess resistance to economically important diseases. Resistance to diseases is relatively easy to integrate because most traits are single genes that are inherited in a dominant fashion. Single genes can have a dramatic effect on the host when the pathogen is present, but rapid evolution of some pathogen genotypes has led to a breakdown of disease resistance after deployment. Our ability to use biotechnology to rapidly deploy stress resistance in popular cultivars and combine multiple genes for resistance offers certain advantages over traditional breeding.

In addition to PRR and R proteins, other genes and mechanisms have the potential to be used to increase disease resistance in potato using biotechnology. One such example is the eIF4E gene that has been found to be associated with virus resistance in many plant species (Nicaise et al. 2003; Gao et al. 2004; Yoshii et al. 2004; Kang et al. 2005; Kanyuka et al. 2005; Stein et al. 2005; Nieto et al. 2006, 2007; Ibiza et al. 2010; Naderpour et al. 2010; Piron et al. 2010), including resistance to potato virus Y in potato, tomato, and pepper (Ruffel et al. 2002, 2005; Cavatorta et al. 2011; Duan et al. 2012). Variants of eIF4E confer resistance to PVY in the potato wild species relatives S. chacoense, S. demissum, and S. etuberosum (Duan et al. 2012), permitting the eventual use of this gene in future biotech potato varieties. Unlike PRR or R proteins, the eIF4E protein does not recognize the presence of a specific pathogen molecule to elicit resistance. Instead, it is a host protein required for proper translation of the viral genomic RNA. Mutations within eIF4E render the protein unusable by the virus and therefore the virus is unable to replicate within the plant cell (Ruffel et al. 2002). In pepper and tomato, eIF4E-mediated resistance is inherited in a recessive manner (Ruffel et al. 2002, 2005). However, introduction of the pepper gene into tomato or potato results in resistance that is dominant over the expression of the endogenous eIF4E variant (Kang et al. 2007; Cavatorta et al. 2011), demonstrating that deployment of eIF4E-based resistance from wild relatives into tetraploid potato is feasible without the need for removal or silencing of the endogenous susceptible allele. The mechanism by which the introduction of this eIF4E using biotechnology results in a switch from recessive to dominant resistance is not well understood and is currently a focus of multiple research projects. 2351a5e196