Menq-Jiau Tseng

Expression of a Bacillus thuringiensis toxin (cry1Ab) gene in cabbage (Brassica oleracea L. var. capitata L.) chloroplasts confers high insecticidal efficacy against Plutella xylostella

Chloroplast genetic engineering is an environmentally friendly approach, where the foreign integrated gene is often expressed at a higher level than nuclear transformation. The cry1Ab gene was successfully transferred into the cabbage chloroplast genome in this study. The aadA and cry1Ab genes were inserted into the pASCC201 vector and driven by the prrn promoter. The cabbage-specific plastid vectors were transferred into the chloroplasts of cabbage via particle gun mediated transformation. Regenerated plantlets were selected by their resistance to spectinomycin and streptomycin. According to antibiotic selection, the regeneration percentage of the two cabbage cultivars was 4–5%. The results of PCR, Southern, Northern hybridization and western analyses indicated that the aadA and cry1Ab genes were not only successfully integrated into the chloroplast genome, but functionally expressed at the mRNA and protein level. Expression of Cry1Ab protein was detected in the range of 4.8–11.1% of total soluble protein in transgenic mature leaves of the two species. Insecticidal effects on Plutella xylostella were also demonstrated in cry1Ab transformed cabbage. The objectives of this study were to establish a gene transformation system for Brassica chloroplasts, and to study the possibility for insect-resistance in dicot vegetables using chloroplast gene transformation.

Effect of LAB 173711, an ABA Analogue, on Low Temperature Resistance of Suspension Cultured Sugarcane Cells

Summary The effect of LAB 173711, a synthetic analogue of abscisic acid, on the response of suspension-cultured sugarcane ( Saccharum officinarum L.) cells under low-temperature stress was evaluated. Cells grown at 10°C or 4°C for 5 d showed a remarkably reduced growth rate as evaluated with TTC reduction, but did not exhibit any symptoms of chilling injury. LAB 173711 application did not improve the lowered growth rate observed under such chilling conditions. By stepwise reducing temperature to evaluate freezing tolerance, the LT 50 for sugarcane cells is about -2°C, while 10 -6 M of LAB 173 711 lowered this value significantly to approximately -6°C. LAB 173711 application also affected some physiological processes: Respiration and the activities of a-amylase and peroxidase are increased. Soluble sugars, reducing sugars, soluble proteins, and free amino acid contents were increased, the combination of which would lead to a reduced osmotic potential.