Robert T. Fraley

In vitro transformation of petunia cells by an improved method of co-cultivation with A. tumefaciens strains

SummaryA method (termed co-cultivation) for transforming plant cells in vitro with A. tumefaciens strains, which was originally developed by Marton et al. (1978) Nature 277: 129–131, has been modified by the incorporation of a novel feeder plate culture system and been extended to use with petunia protoplasts. Using efficient cell plating and selection conditions for phytohormone-independent growth, large numbers of independent transformed calli can be obtained efficiently (∼10-1) and in less than 3 weeks following protoplast isolation. Southern hybridization analysis has confirmed that the majority of the resulting in vitro transformants contain a single copy of full length T-DNA.The high efficiency of this procedure allows simple screening to identify plant cells transformed by Ti plasmids attenuated by deletion of internal T-DNA regions. Results are presented that demonstrate the co-cultivation method can be used in conjunction with short term assays for monitoring plant gene expression.

Current Vectors for Plant Transformation

Publisher Summary One of the most significant recent advances in the area of plant molecular biology has been the development of the Agrobacterium tumefaciens Ti plasmid as a vector system for the transformation of plants. Ti plasmid transformation vectors provide a facile means to introduce homologous and heterologous DNAs and genes into plants. This ability to transfer genetic information between plants and other organisms permits investigators to study the temporal and tissue-specific expression of genes as well as the stability of the gene products. With this tool, the promoter regions responsible for light-regulated expression of certain genes and the portions of transit peptides responsible for proper compartmentalization of proteins within the plant cell are being elucidated. This chapter discusses the correct tissue-specific and developmentally regulated expression of several reintroduced genes. The Ti transformation system has also been adapted for the study of virus host range, symptom production, and replication, as well as host cell recombination processes. For crop improvement uses, the Ti transformation system has been used to obtain plants that are resistant to the nonselective herbicide Roundup®, which express the Bacillus thuringiensis crystal toxin and are resistant to tobacco hornworm and that produce the tobacco mosaic virus coat protein and are resistant to superinfection by virulent strains of this virus.

Plant biotechnology news and views

Everyone involved in plant research today is aware of the increasing interest that industry is displaying towards the emerging field of plant molecular biology. There is a growing list of venture capital companies involved in agricultural research (and university scientists who are joining them) and a lot of talk about increasing crop yields and making drought resistant or herbicide resistant plants. The fact is that this a most exciting period to be doing plant research and a most unusual one for universities and companies. The opportunity exists to initiate combined research efforts to greatly increase our understanding of basic plant biology and to apply this knowledge to scientific and commercial problems. Accomplishing these long-range goals will require effective communication of the problems experienced by as well as the breakthroughs achieved by scientists in the broad area of plant biotechnology. In Biotechnology News we will report on the issues and results which impinge this growing field; included will be descriptions of the progresss, advances and patents in the areas of plant molecular biology, biochemistry, genetics and tissue culture. In addition, periodic updates on key problems dealing with the practical application of this technology to plant systems will be presented by leading academic and industrial scientists.