Screening for transgenic plant cells that highly express a target gene from genetically mixed cells

To establish a strategy for stably and highly expressing a target gene in transformed plant cell suspensions, we developed the co-selection method that linked the hygromycin phosphotransferase gene (hph) to the beta-glucuronidase (uidA, GUS) gene in the opposite direction under the same transcriptional regulation of the cauliflower mosaic virus (CaMV) 35S promoter. The linked genes were transferred into a tobacco BY-2 cell suspension, which was cultivated under various levels of the antibiotic pressure. Under the high pressure of hygromycin, GUS expression was increased and maintained over 1.5 years. We presented a successful example for selecting the plant cell suspension that highly expressed the target gene out of genetically heterogeneous cells. (C) 2002 Elsevier Science B.V. All rights reserved.