Agrobacterium Biology And Its Application To Transgenic Plant Production

The broad host range pathogenic bacterium Agrobacterium tumefaciens has been widely studied as a model system to understand horizontal gene flow, secretion of effector proteins into host cells, and plant-pathogen interactions. Agrobacterium-mediated plant transformation also is the major method for generating transgenic plants for research and biotechnology purposes. Agrobacterium species have the natural ability to conduct interkingdom genetic transfer from bacteria to eukaryotes, including most plant species, yeast, fungi, and even animal cells. In nature, A. tumefaciens causes crown gall disease resulting from expression in plants of auxin and cytokinin biosynthesis genes encoded by the transferred (T-) DNA. Gene transfer from A. tumefaciens to host cells requires virulence (vir) genes that reside on the resident tumor-inducing (Ti) plasmid. In addition to T-DNA, several Virulence (Vir) effector proteins are also translocated to host cells through a bacterial type IV secretion system. These proteins aid in T-DNA trafficking through the host cell cytoplasm, nuclear targeting, and T-DNA integration. Genes within native T-DNAs can be replaced by any gene of interest, making Agrobacterium species important tools for plant research and genetic engineering. In this research topic, we provided updated information on several important areas of Agrobacterium biology and its use for biotechnology purposes.

Agrobacterium is a plant pathogen which causes the “crown-gall” disease, a neoplastic growth that results from the transfer of a well-defined DNA segment (“transferred DNA”, or “T-DNA”) from the bacterial Ti (tumor-inducing) plasmid to the host cell, its integration into the host genome, and the expression of oncogenes contained on the T-DNA. The molecular machinery, needed for T-DNA generation and transport into the host cell and encoded by a series of chromosomal (chv) and Ti-plasmid virulence (vir) genes, has been the subject of numerous studies over the past several decades. Today, Agrobacterium is the tool of choice for plant genetic engineering with an ever expanding host range that includes many commercially important crops, flowers, and tree species. Furthermore, its recent application for the genetic transformation of non-plant species, from yeast to cultivated mushrooms and even to human cells, promises this bacterium a unique place in the future of biotechnological applications. The book is a comprehensive volume describing Agrobacterium's biology, interactions with host species, and uses for genetic engineering.

The aim of Transgenic Plants: Methods and Protocols is to provide a source of information to guide the reader through a wide range of frequently used, broadly applicable, and easily reproducible techniques involved in the gene- tion of transgenic plants. Its step-by-step approach covers a series of methods for genetically transforming plant cells and tissues, and for recovering whole transgenic plants from them. The volume then moves on to the use of sele- able and reporter markers, positive selection, marker elimination after rec- ery of transgenic plants, and the analysis of transgene integration, expression, and localization in the plant genome. Although contributors usually refer to model plants in most chapters, the protocols described herein should be widely applicable to many plant species. The last two sections are devoted to me- ods of risk assessment and to exploring the current and future applications of transgenic technology in agriculture and its social implications in a case study. Transgenic Plants: Methods and Protocols is divided into six major s- tions plus an introduction, comprising 27 chapters. Part I, the Introduction, is a review of the past, present, and perspectives of the transgenic plants, from the discovery of Agrobacterium tumefaciens as a feasible transformation vector, to its use as a tool to study gene expression and function, and the current and possible future applications of this technology in agriculture, industry, and medicine.

Since the first transgenic plants were produced back in the early 1980s, there have been substantial developments towards the genetic engineering of most crops of our world. Initial studies using isolated plant cells and removing their cell walls to form protoplasts, offered the possibility of transferring genetic material by Agrobacterium-mediated gene transfer, chemical agents or electrical charges. However, in those cases were isolated protoplasts could be transformed, often, a shoot regeneration system was not available to induce the production of transgenic plants and any such regenerated plants were subject to mutation or chromosomal of cultured plant organs, such as leaf abnormalities. By the mid-1980s, the use disks, offered the convenience of combining gene transfer, plant regeneration and selection of transformants in a single system. This approach, enabled the production of stable, phenotypically-normal, transgenic potato and tomato plants in culture. By the late 1980s, the use of biolistics offered a means of inserting foreign genes into plant cells which where inaccessible to Agrobacterium infection. Even today, this technology is now standard practice for the production of some transgenic plants.

Designed to inform and inspire the next generation of plant biotechnologists Plant Biotechnology and Genetics explores contemporary techniques and applications of plant biotechnology, illustrating the tremendous potential this technology has to change our world by improving the food supply. As an introductory text, its focus is on basic science and processes. It guides students from plant biology and genetics to breeding to principles and applications of plant biotechnology. Next, the text examines the critical issues of patents and intellectual property and then tackles the many controversies and consumer concerns over transgenic plants. The final chapter of the book provides an expert forecast of the future of plant biotechnology. Each chapter has been written by one or more leading practitioners in the field and then carefully edited to ensure thoroughness and consistency. The chapters are organized so that each one progressively builds upon the previous chapters. Questions set forth in each chapter help students deepen their understanding and facilitate classroom discussions. Inspirational autobiographical essays, written by pioneers and eminent scientists in the field today, are interspersed throughout the text. Authors explain how they became involved in the field and offer a personal perspective on their contributions and the future of the field. The text's accompanying CD-ROM offers full-color figures that can be used in classroom presentations with other teaching aids available online. This text is recommended for junior- and senior-level courses in plant biotechnology or plant genetics and for courses devoted to special topics at both the undergraduate and graduate levels. It is also an ideal reference for practitioners.

The green revolution led to the development of improved varieties of crops, especially cereals, and since then, classical or molecular breeding has resulted in the creation of economically valuable species. Thanks to recent developments in genetic engineering, it has become possible to introduce genes from different sources, such as bacteria, fungi, viruses, mice and humans, to plants. This technology has made the scientific community aware of the critical role of transgenics, not only as a means of producing stress tolerant crops but also as a platform for the production of therapeutics through molecular farming. This book discusses the commercial applications of plant transgenic technologies, including the use of transgenic cell culture approachesto improve the production of metabolites and high-value therapeutics as well as transgenic plants in pest management. It also explores generation of novel vectors, protein production using chloroplast engineering and the latest developments in this area, such as genome editing in plants. Featuring general discussions and research papers by leading international experts, it is a valuable resource for scientists, teachers, students and industrialists working in the field.

Genetic transformation of plants has revolutionized both basic and applied plant research. Plant molecular biology and physiology benefit from this power fool, as well as biotechnology. This book is a review of some of the most significant achievements that plant transformation has brought to the fields of Agrobacterium biology, crop improvement and, flower, fruit and tree amelioration. Also, it examines their impact on molecular farming, phytoremediation and RNAi tools.

Volumes 1 and 2 of Transgenic Plants assemble important information on transgenic crops which has appeared scattered in many different publications. These two volumes are a significant milestone in plant/agricultural biology, promote the practical application of recombinant DNA technology, and assist in transforming the agricultural industry.