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Endosperm‐specific activity of a zein gene promoter in transgenic tobacco plants
Author(s) -
Schernthaner J. P.,
Matzke M. A.,
Matzke A. J. M.
Publication year - 1988
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1988.tb02938.x
Subject(s) - biology , endosperm , transgene , nicotiana tabacum , genetically modified crops , gene , genetics , botany
Transgenic tobacco plants containing maize gene (Z4) encoding a 23‐kd zein protein, which is normally synthesized in the endosperm of maize seeds, were obtained using a modified Ti plasmid vector. Although a polyadenylated transcript homologous to the Z4 gene was present in the seeds of some of these transgenic plants, zein protein could not be detected in any of the plants tested (35 total). To simplify the analysis of the tissue specificity of the Z4 promoter (Z4 pro ) in different organs of transformed tobacco plants, additional transgenic plants containing the chimeric genes Z4 pro ‐CAT and Z4 pro ‐GUS were produced. Very weak seed‐specific CAT activity was observed in one out of ten Z4 pro ‐CAT‐transformed plants. When the more sensitive GUS assay system was used to evaluate Z4 pro activity in tobacco, it could be shown in all 11 transgenic plants obtained that GUS activity was restricted to the endosperm tissue of transgenic tobacco seeds. To study the synthesis and stability of the zein proteins in different organs of transgenic tobacco plants, the Z4 protein‐coding region and also a cDNA clone (A30) encoding a 19‐kd zein protein were placed under the control of the 35S promoter (35S pro ) of cauliflower mosaic virus. Undegraded zein proteins of both size classes were detected in roots, leaves and endosperm tissue, but not embryos, of mature seeds from 35S pro ‐zein‐transformed plants. The zein proteins did not appear to be broken down during tobacco seed germination; synthesis of zeins began in green cotyledons.