Abiotic stress induces the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) in plants, which consequently enhances ethylene production and inhibits plant growth. The bacterial ACC deaminase enzyme encoded by the acdS gene reduces stress-induced ethylene production and improves plant growth in response to stress. In this study, overexpression of acdS in Petunia hybrida (‘Mirage Rose’) significantly reduced expression of the ethylene biosynthesis gene ACC oxidase 1 (ACO1) and ethylene production relative to those in wild type (WT) under various abiotic stresses (cold, drought, and salt). The higher reduction of stress-induced ethylene in the transgenic plants, which was due to the overexpression of acdS, led to a greater tolerance to the stresses compared to that in the WT plants. The greater stress tolerances were proven based on better plant growth and physiological performance, which were linked to stress tolerance. Moreover, expression analysis of the genes involved in stress tolerance also supported the increased tolerance of transgenics relative to that with the WT. These results suggest the possibility that acdS is overexpressed in ornamental plants, particularly in bedding plants normally growing outside the environment, to overcome the deleterious effect of ethylene on plant growth under different abiotic stresses. The development of stress-tolerant plants will be helpful to advance the floricultural industry.
This study was conducted to investigate the efficacy of shoot regeneration from different leaf types (normal leaves and vitrified leaves) from three different carnation cultivars ‘Kumbuyl’, ‘Denev’, and ‘Jinju’ using different combinations of 3-indole butyric acid (IBA) and thidiazuron (TDZ) concentrations. The shoot tips cultured on Murashige and Skoog (MS) basal media (Type 1 media) produced normal leaves, while those cultured-on media supplemented with plant growth regulators and/or vitamin (Type 2 media and Type 3 media) produced vitrified leaves for all cultivars. Culture of normal leaf segments on MS medium containing different combinations of IBA and TDZ concentrations induced callus in all treatments; however, the callus was unable to induce shoots and finally became necrotic. In contrast, no callus induction was observed in the control (hormone-free treatment). When vitrified leaf segments underwent the same treatments, shoots were induced from the vitrified leaves (derived from Type 2 media) but were unhealthy and gradually died, whereas those induced from Type 3 media were vitrified and healthy. The optimal combination for the best shoot regeneration and number of shoots per explants varied depending on the genotypes used. The vitrified shoots induced from the leaves of Type 3 media transformed into normal shoots and survived well under greenhouse conditions. According to the results of random amplified polymorphic DNA (RAPD) analysis, the banding patterns of twelve primers that were detected in vitrified leaf-induced normalized shoots were identical to those of normal in vitro grown plants, indicating that no genetic variation had occurred during the procedure. Taken together, this study indicates that vitrified leaves can be used for shoot regeneration of recalcitrant carnation cultivars, regardless of the genotypes and types of vitrified leaves. However, as the number of shoots per explants was still low, further investigation is warranted to obtain a more efficient shoot regeneration protocol for genetic transformation of the cultivars.
Background/Aims: Helicobacter pylori (H. pylori) transmission route is not yet clearly understood. Isolating H. pylori from stool, saliva, and vomitus is very difficult. However, H. pylori could be cultured from feces in the setting of rapid gastrointestinal tract transit. The aim of this study was to isolate H. pylori by culture and PCR in the rectum and terminal ileum during colonoscopy. Methods: Twenty subjects with positive UBT (urea breath test) were included. We performed polymerase chain reaction (PCR) test and culture of H. pylori with the rectal fluid and terminal ileal fluid during colonoscopy. Results: H. pylori was cultured with rectal fluid from 9 (45.0%) of 20 subjects and with ileal fluid from 11 (55.0%) of 20 subjects. H. pylori was a little more frequently cultured from the terminal ileal fluid than the rectal fluid without statistical significance (p>0.05). PCR test detected flaA (16/20, 80.0% and 17/20, 85.0%), 16S rRNA gene (16/20, 80.0% and 17/20, 85.0%), cagA (10/20, 50.0% and 12/20, 60.0%), and ureC (9/20, 45% and 11/20, 54.5%) from the rectal fluid and the terminal ileal fluid, respectively. The specificity and sensitivity of ureC were 100%. Conclusions: H. pylori could be cultured from the rectal fluid and terminal ileal fluid in the setting of rapid gastrointestinal tract transit. These results suggest of fecal-oral transmission of H. pylori. (Korean J Gastroenterol 2010;56:27-32)
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