Dissection of a pollen-specific promoter from maize by transient transformation assays.
We have previously reported the isolation and characterization of a gene (Zm13) from Zea mays which shows a pollen-specific pattern of expression. Stably transformed tobacco plants containing a reporter gene linked to portions of the Zm13 5' flanking region show correct temporal and spatial expression of the gene. Here we present a more detailed analysis of the 5' regions responsible for expression in pollen by utilizing a transient expression system. Constructs containing the beta-glucuronidase (GUS) gene under the control of various sized fragments of the Zm 13 5' flanking region were introduced into Tradescantia and Zea mays pollen via high-velocity microprojectile bombardment, and monitored both visually and with a fluorescence assay. The results suggest that sequences necessary for expression in pollen are present in a region from -100 to -54, while other sequences which amplify that expression reside between -260 and -100. The replacement of the normal terminator with a portion of the Zm13 3' region containing the putative polyadenylation signal and site also increased GUS expression. While the -260 to -100 region contains sequences similar to other protein-binding domains reported for plants, the -100 to -54 region appears to contain no significant homology to other known promoter fragments which direct pollen-specific expression. The microprojectile bombardment of Tradescantia pollen appears to be a good test system for assaying maize and possibly other monocot promoter constructs for pollen expression.
Hamilton
D A
DA
Department of Biological Sciences, State University of New York, Albany 12222.
Roy
M
M
Rueda
J
J
Sindhu
R K
RK
Sanford
J
J
Mascarenhas
J P
JP
D015870:Gene Expression / Q000235:genetics; D005822:Genetic Vectors / Q000235:genetics; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D011058:Pollen / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015183:Restriction Mapping; D014170:Transformation, Genetic / Q000235:genetics; D003313:Zea mays / Q000235:genetics*
D011993:Recombinant Fusion Proteins; D005966:Glucuronidase