Abstract Marker genes have been wildly used for identifying transgenic plants. However, the poor transformation efficiency of most crops necessitates the use of marker genes to identify transgenic plants. Much more concerns are being given to the safety of the resistance marker genes，as the quick development and commercialization of the transgenic plants. Positive selection system has been developed as an efficient alternative by using non-resistance marker genes with biosafety, some of which are sugar metabolic enzyme genes (pmi and xylA), disturbing amino acid metabolic enzyme genes (ak and dapA), green fluorescent protein gene(gfp),β-glucuronidase gene(gus), ribitol operon(rtl), chlorophyllous biosynthesis enzyme gene (hemL).
|
