Isolation of a polyubiquitin promoter and its expression in transgenic potato plants.
A polyubiquitin clone (ubi7) was isolated from a potato (Solanum tuberosum) genomic library using a copy-specific probe from a stress-induced ubiquitin cDNA. The genomic clone contained a 569-bp intron immediately 5' to the initiation codon for the first ubiquitin-coding unit. Two chimeric beta-glucuronidase (GUS) fusion transgenes were introduced into potato. The first contained GUS fused to a 1156-bp promoter fragment containing only 5' flanking and 5' untranslated sequences from ubi7. The second transgene contained GUS translationally fused to the carboxy terminus of the first ubiquitin-coding unit and thus included the intron present in the 5' untranslated region of the polyubiquitin gene. Both ubi7-GUS transgenes were activated by wounding in tuber tissue and in leaves by application of exogenous methyl jasmonate. They were also expressed constitutively in the potato tuber peel (outer 1-2 mm). Both transgenes were actively expressed in mature leaves. Exceptionally high levels of expression were observed in senescent leaves. Transgenic clones containing the ubi7 intron and the first ubiquitin-coding unit showed GUS expression levels at least 10 times higher than clones containing GUS fused to the intronless promoter.
Demeter Biotechnologies, Ltd., Research Triangle Park, North Carolina 27709, USA.
J E
JE
Garbarino
T
T
Oosumi
W R
WR
Belknap
D001483:Base Sequence; D001704:Biopolymers / Q000096:biosynthesis* / Q000235:genetics*; D003062:Codon; D017931:DNA Primers; D015870:Gene Expression; D017343:Genes, Plant; D015698:Genomic Library; D005966:Glucuronidase / Q000096:biosynthesis / Q000378:metabolism; D007438:Introns; D007700:Kinetics; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified; D016133:Polymerase Chain Reaction; D025821:Polyubiquitin; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D011198:Solanum tuberosum / Q000378:metabolism*; D014452:Ubiquitins / Q000096:biosynthesis* / Q000235:genetics*
D001704:Biopolymers; D003062:Codon; D017931:DNA Primers; D011993:Recombinant Fusion Proteins; D014452:Ubiquitins; D025821:Polyubiquitin; D005966:Glucuronidase