Direct Gene Transfer to Plants

Abstract

Evidence for direct, gene-mediated stable genetic transformation of plant cells of Nicotiana tabacum is presented. A selectable hybrid gene comprising the protein coding region of the Tn5 aminoglycoside phosphotransferase type II gene under control of cauliflower mosaic virus gene VI expression signals was introduced into plant protoplasts as part of an Escherichia coli plasmid. The gene was stably integrated into plant genomic DNA and constitutively expressed in selected, drugresistant, protoplast-derived cell clones. The mode of integration of the foreign gene into the plant genome resembled that observed for DNA transfection of mammalian cells. Plants regenerated from transformed cell lines were phenotypically normal and fertile, and they maintained and expressed the foreign gene throughout the development of vegetative and generative organs. Microspores, grown in anther culture, developed into resistant and sensitive haploid plantlets. Genetic crossing analysis of one of the transformed plants revealed the presence of one dominant trait for kanamycin resistance segregating in a Mendelian fashion in the F1 generation.

Anther Culture in Crop Plants: Progress and Perspectives

“…Potrykus and his co-authors predicted the potentiality of the anther in genetic transformation as anther cultured isolated pollen has remarkable regeneration frequency (Potrykus et al 1985;Potrykus 1988) which has proved further. In genetic transformation, the single-celled micro-spore, haploid embryo, or calli act as the recipient of the gene of interest.…”

Biofortification of essential nutritional compounds and trace elements in rice and cassava

“…Genetic transformation does not change the genetic background of the plant, in contrast to breeding. This process represents the best method of adding a new characteristic to a plant without changing its other properties (Klein & Fitzpatrick-McElligott, 1993;Potrykus et al 1995;Sinclair et al 2004). In the following paper the methodology for genetically modifying a plant will be discussed, with particular reference to the most important approaches for biofortification in rice and cassava.…”

Regeneração de plantas de Phaseolus vulgaris L. a partir de calos e transformação genética via Agrobacterium.

“…É necessária a utilização de um gene marcador que possa ser facilmente detectado. Além disto, é uma metodologia patenteada e exige equipamentos específicos (Potrykus & Spangenberg, 1995;Brasileiro & Carneiro, 1998).…”

“…Assim, um pré-requisito essencial é um protocolo eficiente de regeneração aliado a um sistema de seleção que possibilite a recuperação de plantas a partir destas células (Potrykus & Spangenberg, 1995).…”

“…Os principais fatores a serem considerados na escolha de um determinado gene marcador são: i) a expressão do mesmo não deve interferir no metabolismo normal das células transformadas, ii) seu produto deve proteger, de modo efetivo, as células transformadas, das propriedades inibitórias de crescimento do agente seletivo, além de ter uma boa difusão nos tecidos, de forma a permitir uma distinção fenotípica clara entre as células transformadas e as não transformadas e, iii) a exposição do explante transgênico ao agente seletivo, não deve afetar seu subseqüente crescimento e regeneração em plantas inteiras e férteis (Potrykus & Spangenberg, 1995).…”