S Omirulleh | PubMed Health

PubMed1997

Factors affecting transient expression of vector constructs in wheat protoplasts.

Direct uptake of reporter gene constructs with the bacterial beta-glucuronidase (GUS) gene fused to various promoters was achieved to embryogenic cell suspension culture-derived protoplasts of GK Ságvári winter wheat (Triticum aestivum L.) with polyethylene glycol (PEG) treatment. Based on GUS specific activity values, it was found that Mg2+ with PEG at 20% final concentration can significantly increase the transient expression in wheat protoplasts in comparison to the Ca(2+)-containing medium. The optimum incubation time in transformation mixture was 5-10 min at 25 degrees C. Transient GUS expression as detected by spectrofluorimetry was positively correlated with the time elapsed after DNA uptake (with maximum activity at 48 h), and the incubation time in GUS reaction mixture. It was also found that the protoplast culture medium plays an important role in the efficiency, and the treated wheat protoplasts cultured in KM medium showed a higher GUS activity than those kept in GM medium. Among the five plasmid constructs 6-16-fold higher promoter activity has been achieved with pKM794 driven by CaMV 35S promoter plus two enhancer elements than with the other constructs tested.

Gene Expression↗

PubMed1996

A zinc-finger-type transcription factor WZF-1 that binds to a novel cis-acting element of histone gene promoters represses its own promoter.

WZF-1 is a zinc-finger protein which binds to the wheat histone gene promoter. Southwestern-binding analyses revealed that it bound a CACTC sequence, a novel positive cis-acting element. The activity of WZF-1 gene promoter, containing six CACTC sequences, was markedly reduced when WZF-1 was co-expressed, suggesting that WZF-1 is a transcriptional repressor.

Base Sequence↗

PubMed1993

Activity of a chimeric promoter with the doubled CaMV 35S enhancer element in protoplast-derived cells and transgenic plants in maize.

A reproducible and efficient transformation system has been developed for maize that is based on direct DNA uptake into embryogenic protoplasts and regeneration of fertile plants from protoplast-derived transgenic callus tissues. Plasmid DNA, containing the beta-glucuronidase (GUS) gene, under the control of the doubled enhancer element (the -208 to -46 bp upstream fragment) from CaMV 35S promoter, linked to the truncated (up to -389 bp from ATG) promoter of wheat, alpha-amylase gene was introduced into protoplasts from suspension culture of HE/89 genotype. The constructed transformation vectors carried either the neomycin phosphotransferase (NPTII) or phosphinothricin acetyltransferase (PAT) gene as selective marker. The applied DNA uptake protocol has resulted at least in 10-20 resistant calli, or GUS-expressing colonies after treatment of 10(6) protoplasts. Vital GUS staining of microcalli has made possible the shoot regeneration from the GUS-stained tissues. 80-90% of kanamycin or PPT resistant calli showed GUS activity, and transgenic plants were regenerated from more than 140 clones. Both Southern hybridization and PCR analysis showed the presence of introduced foreign genes in the genomic DNA of the transformants. The chimeric promoter, composed of a tissue specific monocot promoter, and the viral enhancer element specified similar expression pattern in maize plants, as it was determined by the full CaMV 35S promoter in dicot and other monocot plants. The highest GUS specific activity was found in older leaves with progressively less activity in young leaves, stem and root. Histochemical localization of GUS revealed promoter function in leaf epidermis, mesophyll and vascular bundles, in the cortex and vascular cylinder of the root. In roots, the meristematic tip region and vascular tissues stained intensively. Selected transformants were grown up to maturity, and second-generation seedlings with segregation for GUS activity were obtained after outcrossing. The GUS-expressing segregants carried also the NPTII gene as shown by Southern hybridization.

Aminobutyrates↗