The Competence of Maize Shoot Meristems for Integrative Transformation and Inherited Expression of Transgenes.
We have developed a novel and reproducible system for recovery of fertile transgenic maize (Zea mays L.) plants. The transformation was performed using microprojectile bombardment of cultured shoot apices of maize with a plasmid carrying two linked genes, the Streptomyces hygroscopicus phosphinothricin acetyltransferase gene (bar) and the potato proteinase inhibitor II gene, either alone or in combination with another plasmid containing the 5[prime] region of the rice actin 1 gene fused to the Escherichia coli [beta]-glucuronidase gene (gus). Bombarded shoot apices were subsequently multiplied and selected under 3 to 5 mg/L glufosinate ammonium. Co-transformation frequency was 100% (146/146) for linked genes and 80% (41/51) for unlinked genes. Co-expression frequency of the bar and gus genes was 57% (29/51). The co-integration, co-inheritance, and co-expression of bar, the potato proteinase inhibitor II gene, and gus in transgenic R0, R1, and R2 plants were confirmed. Localized expression of the actin 1-GUS protein in the R0 and R1 plants was extensively analyzed by histochemical and fluorometric assays.
Zhong
H.
H
202 Pesticide Research Center, Department of Crop and Soil Sciences, Michigan State University, East Lansing, Michigan 48824-1311 (H.Z., B.S., D.W., S.Z., M.B.S.).
Sun
B.
B
Warkentin
D.
D
Zhang
S.
S
Wu
R.
R
Wu
T.
T
Sticklen
M. B.
MB