Selectable Markers and Reporter Genes: A Well Furnished Toolbox for Plant Science and Genetic Engineering

Abstract

Marker genes (MGs) are essential tools for plant research and biotechnology. Positive selectable marker genes (SMGs) are used in genetic transformation to allow only transgenic cells to grow and develop and are necessary for efficient transformation. Negative SMGs confer a selective disadvantage to the cells that express them, and have several uses in both basic and applied research. Reporter genes (RGs) make it possible to easily screen cells or tissues for their expression. Several tens of different genes from bacteria, fungi, plants, and animals have been demonstrated to function as SMGs. Here, SMGs are classified based on the mechanism of action of the gene products. To provide the readers with practically useful information, details on transformation and selection efficiency are given. RGs are the object of intense research. Refinement of existing RGs and development of new ones is constant, and has provided powerful aids for fine studies on cell biology and more efficient genetic engineering. They are classified as vital and non vital, depending on the possibility to screen their expression in living cells. The effect of MG expression on the phenotype and their safety in crops is briefly discussed. The picture emerging from this literature review is that a plentiful array of powerful and versatile tools for basic and applied research is available.