جستجوی مقالات مرتبط با کلیدواژه "glycine betaine" در نشریات گروه "بیوتکنولوژی و ژنتیک گیاهی"

Compatible solutes or osmoprotectants serve as nontoxic solutes for cytoplasmic osmoregulation. Glycine betaine is one of the most critical compatible solutes accumulated by many plants in response to adverse effects of various abiotic stresses. In some species named Glycine betaine accumulators, Glycine betaine is synthesized by a two-step oxidation of choline by choline monooxygenase (CMO) and betaine aldehyde dehydrogenase (BADH) enzymes. According to the Arabidopsis thaliana genome database (TAIR) there are the most likely two AtALDH8 and AtALDH9 genes coding BADH enzyme. In this study, using the relative expression analysis via quantitative RealTime PCR, it has been evaluated how the expression pattern of these genes affected by drought levels in Arabidopsis thaliana tissues including fast expanding leaves, fully expanded leaves, and roots. It has been denoted that the mRNA induction level of the AtALDH9 gene varies in tissues in response to drought levels. However, the expression of AtALDH8 gene is affected negligibly by these factors. While 12-day of water withholding made no changes in the expression level of AtALDH9 gene in fully expanded leaves, the expression level of the gene were changed at about 0.7-fold and 4-fold in fast expanding leaves and roots, respectively. Differently, after 16-day of water withholding the expression level of AtALDH9 gene rose about 2.5-fold in fast expanding leaves and reduced about 0.2-fold in both fully expanded leaves and roots. Generally, it seems that AtALDH9 is the gene accountable in Arabidopsis in response to drought stress.

One of the plant resistant mechanisms to abiotic stresses is production of a compatible solute named glycine betaine. Choline is the precursor of this important metabolite and it is also essential compound for the structural integrity and signaling of cell membrane. In plants, the most important step of choline production is catalyzed by cytoplasmic phosphoethanolamine N-methyltransferase (PEAMT ; EC 2.1.1.103) enzyme. In this study, PEAMT gene from spinach (Spinacia oleracea Iranian landrace) was amplified using specific primers and cloned into an intermediate cloning vector (pJET). In order to overexpression of PEAMT gene, the construct of PBI121GUS-9:PEAMT was made and finally was transferred to the Agrobacterium tumefaciens GV3101 (PMP90). Floral dip method was used for transformation and initial analysis of putative transgenic plants was tested in selective medium containing kanamycin. Then resistant seedlings at the molecular level were evaluated using PCR and RT-PCR methods. Results confirmed plant transformation in the level of transcription. Subsequently, The phenotypic analysis under salt stress showed that the main root length of transgenic plants was significantly longer than control nontransgenics. In adition, glycinebetaine contents and peroxidase activity were significantly higher in transgenic compare to non-transgenics control plants.

In order to produce a marker-free transgenic rice with improved tolerance to salinity and drought stresses, expression vectors pABRII-Chl and pABRII-Cyt containing "choline oxidase" gene (with or without leader sequence respectively) were constructed from pChl and pCyt and pTR 132 for co-transformation. The pChl and pCyt vectors were digested with HindIII-BamH and BamHIEcoRI enzymes. Then the resulting sequences were ligated and inserted into expression vector pTRA132, in which the HindIII-EcoRI fragment (hph gene) had been deleted. The constructs pABRII-Chl or pABRII-Cyt and pTRA132 (containing hph gene) were introduced into embryogenic calli derived from the mature seeds of a rice cv. Hashemi by biolistic transformation method. Then putative transformants were screened after 3 rounds of selection on N6 medium containing increasing concentrations of Hygromycin B from 60 to 80 mg/L. Finally, Hygromycin resistant calli were regenerated on MS medium supplemented with 50 mg/L Hygromycin B. Putative transgenic rice plants were analyzed by polymerase chain reaction PCR. Then, four of the transgenic plants were analyzed using Southern blotting. Each transgenic plant received one copy number of both choline oxidase and hph genes. Expression of the transgene was confirmed by reverse transcription PCR. The high frequency of transformation rate in this study showed that co-transformation method is a reliable method for stable transformation with the goal to make markerfree transgenic plants in subsequent steps.