Submitted to: Maize Genetics Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/13/2003
Publication Date: 3/13/2003
Citation: BICAR, E., LEE, M., SCOTT, M.P. EXPRESSION AND INHERITANCE PATTERNS OF A MODIFIED PORCINE A-LACTALBUMIN TRANSGENE IN MAIZE KERNELS. MAIZE GENETICS CONFERENCE ABSTRACTS. 2003. http://www.maizegdb.org/cgi-bin/displayrefrecord.cgi?id=885074. Interpretive Summary:
Technical Abstract: A codon-adjusted version of a gene encoding the porcine milk protein alpha-lactalbumin was synthesized to create maize with improved nutritional quality. Three expression vectors containing the synthetic gene were constructed and transformed into maize callus by particle bombardment. The constructs (P45, P64, P57) differ in their promoters and subcellular targeting domains. The objective of this study was to characterize the expression and inheritance patterns of these transgenes. Alpha-La DNA sequences were detected by PCR analysis of F1 plants in 6 of 8 events of P64, 6 events of P45 and 4 of 5 events of P57, indicating that the alpha-La gene was integrated into the maize genome and transmitted to the F1 generation. Western blot analysis indicated that the alpha-La protein accumulated in the endosperm, showing that the transgenes were functional. Expression and inheritance of the alpha-La transgenes were assessed. In 5 of 6 events of P64, the alpha-La transgene was inherited as a single locus through the F3 generation. In P45, irregular expression and inheritance patterns were observed. In 3 events, the alpha-La transgene was inherited as a single locus in the BC1F1 and F2 generations. In the F3 generation, segregation distortion manifested by an increase in frequency of kernels with no detectable alpha-La protein was observed. PCR analysis of these kernels confirmed presence of the alpha-La transgene, indicating that the transgene was not functional. In 2 events that expressed alpha-La in the F1, the alpha-La protein was not detected in the BC1F1 and F2 generations. However, in F3 kernels derived from self-pollination of these F2 null plants, alpha-La was detected, suggesting that the transgene was reactivated. This phenomenon was also observed in the F3 generation in 2 events of P57 that manifested transgene inactivation in the BC1F1 and F2 generations. Possible causes of these irregular inheritance patterns are discussed.