Early transcription of Agrobacterium T-DNA genes in tobacco and maize

• Published in: The Plant cell Vol. 8; no. 5; pp. 873 - 886
• Main Authors: Narasinhulu, S.B. (Colorado State University, Ft. Collins, CO.), Deng, X.B, Sarria, R, Gelvin, S.B
• Format: Journal Article
• Language: English
• Published: England American Society of Plant Physiologists 01-05-1996
• Subjects: ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; ADN; Agrobacterium; AGROBACTERIUM TUMEFACIENS; ARN MENSAJERO; ARN MESSAGER; BACTERIA; Bacterial Proteins - biosynthesis; Bacterial Proteins - genetics; Base Sequence; Coculture techniques; Corn; CULTIVO DE CELULAS; CULTURE DE CELLULE; DNA Primers; DNA, Bacterial - metabolism; DNA, Single-Stranded - metabolism; EXPRESION GENICA; EXPRESSION DES GENES; GENE; GENES; Genes, Bacterial; GLICOSIDASAS; Glucuronidase - biosynthesis; Glucuronidase - genetics; GLYCOSIDASE; Infections; Messenger RNA; Molecular Sequence Data; MUTACION INDUCIDA; Mutagenesis; MUTANT; MUTANTES; MUTATION PROVOQUEE; Nicotiana - metabolism; Nicotiana - virology; NICOTIANA TABACUM; PATOGENICIDAD; PCR; Plant cells; Plants, Toxic; Plasmids; Polymerase Chain Reaction; POUVOIR PATHOGENE; PROTEINAS; PROTEINE; Proteins; Reverse transcriptase polymerase chain reaction; Rhizobium - genetics; Rhizobium - metabolism; RNA; RNA, Messenger - biosynthesis; TRANSCRIPTASA INVERSA; TRANSCRIPTASE INVERSE; Transcription Factors - biosynthesis; Transcription Factors - genetics; Transcription, Genetic; TRANSFERENCIA DE GENES; TRANSFERT DE GENE; TRANSFORMACION GENETICA; TRANSFORMATION GENETIQUE; Virulence Factors; ZEA MAYS; Zea mays - metabolism; Zea mays - virology
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.8.5.873

We developed a sensitive procedure to investigate the kinetics of transcription of an Agrobacterium tumefaciens transferred (T)-DNA-encoded beta-glucuronidase gusA (uidA) gene soon after infection of plant suspension culture cells. The procedure uses a reverse transcriptase-polymerase chain reaction and enables detection of gusA transcripts within 18 to 24 hr after cocultivation of the bacteria with either tobacco or maize cells. Detection of gusA transcripts depended absolutely on the intact virulence (vir) genes virB, virD1/virD2, and virD4 within the bacterium. Mutations in virC and virE resulted in delayed and highly attenuated expression of the gusA gene. A nonpolar transposon insertion into the C-terminal coding region of virD2 resulted in only slightly decreased production of gusA mRNA, although this insertion resulted in the loss of the nuclear localization sequence and the important omega region from VirD2 protein and rendered the bacterium avirulent. However, expression of gusA transcripts in tobacco infected by this virD2 mutant was more transient than in cells infected by a wild-type strain. Infection of tobacco cells with an Agrobacterium strain harboring a mutant virD2 allele from which the omega region had been deleted resulted in similar transient expression of gusA mRNA. These data indicate that the C-terminal nuclear localization signal of the VirD2 protein is not essential for nuclear uptake of T-DNA and further suggest that the omega domain of VirD2 may be required for efficient integration of T-DNA into the plant genome. The finding that the initial kinetics of gusA gene expression in maize cells are similar to those shown in infected tobacco cells but that the presence of gusA mRNA in maize is highly transient suggests that the block to maize transformation involves T-DNA integration and not T-DNA entry into the cell or nuclear targeting