Gap-Chae Chung

Sensitivity of plasma membrane H+-ATPase of cucumber root system in response to low root temperature

Abstract Cucumber plants (Cucumis sativus L.) were grown at different root temperatures and the H+-ATPase activities in the root plasma membranes were investigated. Electrolyte leakages and the amount of water transported from root to shoot indicated the sensitivity of cucumber root systems to low root temperature. The increase in H+-ATPase activity after 1 day of low root temperature treatment was reversed and gradually diminished as root temperatures of 10 °C continued for another 6 days. The H+-transport rate of the plasma membranes and the transcriptional activity of the corresponding gene expression closely followed the H+-ATPase activity. The role of H+-ATPase in root plasma membranes in terms of the root acclimation process at low root temperature is discussed.

Activity of the Arabidopsis blue copper-binding protein gene promoter in transgenic tobacco plants upon wounding

Abstract. Wound-inducible gene promoters can be valuable in regulating the expression of resistance genes for insect and/or pathogen attack. The transcriptional regulatory region (from –1294 to +247) of a wound-inducible Arabidopsis gene encoding a blue copper-binding (BCB) protein was fused to the β-glucuronidase (GUS) gene in a plant transformation vector. Stable integration of the single Arabidopsis BCB/GUS gene into the tobacco genome resulted in strongly induced GUS activity upon wounding in the homozygous T2 plants. GUS gene expression was limited to the plant cells surrounding the wound site, showing localized induction. However, expression of the chimeric gene was delayed in time and reduced in intensity when compared with the response of BCB gene expression in Arabidopsis, suggesting that foreign gene promoter activity is reduced in the heterologous host

Characterization of a glutathione S-transferase gene arranged in tandem with the ATGST 1 gene in Arabidopsis thaliana

Summary A novel glutathione S-transferase gene, designated ATGST 11 , is tandemly arranged with the ATGST 1 gene which is known to be regulated by various environmental stresses in the Arabidopsis genome. The ATGST 11 gene structure is very similar to the ATGST 1 gene with complete conservation of intron position and with a highly conserved nucleotide sequence, suggesting that they likely arose by duplication of a single primordial gene. The ATGST11 gene contains the entire transcriptional unit in 3 exons interrupted by two introns, which predicts a GST of 209 amino acids. The gene is proven to be constitutively transcribed at a very low level in root, stem, leaf and flower. Cis elements of the gene promoter, possibly responsible for the transcriptional regulation, may be mutated, and this suggests that gene transcription is not induced by environmental stimuli.

Calcium localization in root cells, phosphorylation and water transport of root system influenced by low root temperature

Cucumber (Cucumis sativus) and figleaf gourd (Cucurbita ficifolia) plants as chilling root temperature-sensitive and — resistant species, respectively, were grown under low root temperature. Calcium localisation in the root cells, in-gel kinase activities and water transport were investigated. Figleaf gourd root cells acquired more calcium when root temperature was lowered. In-gel kinase assays revealed that there is essentially no difference between the two species in terms of signal transduction in response to low root temperature. However, the response of water channels after the application of mercury was different, implying that the ability of maintaining water balance would be important in cold acclimation.