title: Systems for the removal of a selection marker and their combination with a positive marker.
abstract: Many systems have been developed for the removal of a selection marker in order to generate marker-free transgenic plants. These systems consist of (1) a site-specific recombination system (Cre/lox) or a phage-attachment region (attP) to remove the selectable marker gene and (2) a transposable element system (Ac) or a co-transformation system to segregate the gene of interest from the selectable marker gene. Overall, the process is more time-consuming than conventional transformation methods because two rounds of transformation - two steps of regeneration or sexual crossings - are required to obtain the desired transgenic plants. Recently, removal systems combined with a positive marker, denoted as MAT vectors, have been developed to save time and effort by generating marker-free transgenic plants through a single-step transformation. We summarize here the transformation procedures using these systems and discuss their feasibility for practical use.
authors.affiliation: Pulp and Paper Research Laboratory, Nippon Paper Industries Co, 5-21-1, Oji, Kita-ku, Tokyo 114-0002, Japan, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ebinuma
authors.forename: K
authors.initials: K
authors.lastname: Sugita
authors.forename: E
authors.initials: E
authors.lastname: Matsunaga
authors.forename: S
authors.initials: S
authors.lastname: Endo
authors.forename: K
authors.initials: K
authors.lastname: Yamada
authors.forename: A
authors.initials: A
authors.lastname: Komamine