Organ-specific and dosage-dependent expression of a leaf/stem specific gene from potato after tagging and transfer into potato and tobacco plants

Abstract

ST-LS1, a single copy gene from potato displaying a leaf/stem specific gene expression, was tagged by an exon modification and introduced into both potato and tobacco cells using Agrobacterium vectors. After regeneration of whole plants, the expression of the tagged gene was analyzed with respect to its organ specificity and compared to the expression of the corresponding resident gene. The expression of the transferred gene in transgenic plants closely followed the expression of the resident gene. No marked influence of the plant species serving as host was observed. The level of expression of the introduced gene varied by a factor of at least 100 in independent transformants when normalized to the expression of the resident gene. Southern analysis performed on the transformed plants indicated a correlation between copy number of the introduced gene and its expression level. The activity of the tagged gene as well as of the resident gene was significantly inhibited by treatment of the transgenic plants with the herbicide norfluorazon, indicating that this gene activity is dependent on the presence of functional chloroplasts in the leaves.

Silencing in Arabidopsis T-DNA Transformants: The Predominant Role of a Gene-Specific RNA Sensing Mechanism versus Position Effects

“…On the other hand, the analysis of a small number of single-copy T-DNA transformants did not reveal evidence that transgene transcript levels were affected by position effects (Hobbs et al, 1990). Direct proportionality between transgene copy number and expression level has been reported (Stockhaus et al, 1987;Hobbs et al, 1993;Ku et al, 1999), whereas several other studies described a correlation between silencing and high transgene doses and/or repeat arrangements of transgenes (Hobbs et al, 1990;Jorgensen et al, 1996;Que et al, 1997).…”

“…These findings reconcile the seemingly contradictory data that were obtained in previous studies of different transgene populations in plants. On the one hand, a positive correlation between transgene copy number and expression was reported (Stockhaus et al, 1987;Hobbs et al, 1993;Ku et al, 1999); on the other hand, many transformants containing multiple copies of an introduced gene showed low levels of transgene expression and/or silencing (Hobbs et al, 1990;Jorgensen et al, 1996).…”

Diploid potato (Solanum tuberosum L.) as a model crop to study transgene expression

“…However, strong and stable GUS-expressing and weak GUS-expressing plants also differed in the number of transgene copies integrated within the genome. The transgene copy number can be positively [32,33] or negatively associated with transgene expression [34,35]. Schubert et al [36] characterized the correlation between the number of transgene copies and expression in A. thaliana.…”

The Bt gene cry2Aa2 driven by a tissue specific ST-LS1 promoter from potato effectively controls Heliothis virescens

“…The ST-LS1 gene promoter was originally reported by Stockhaus et al (1987Stockhaus et al ( , 1989. In potato, the endogenous ST-LS1 gene encodes a 10 kDa protein in the oxygen-evolving complex of photosystem II.…”

“…The leaf tissue specific promoter of a gene encoding a light inducible protein ST-LS1 from potato has been reported to express heterologous genes in the green tissues of plants (Stockhaus et al, 1987;van Voorthuysen et al, 2000). They, however, studied metabolic enzymes not required at a high dose.…”