Phần III: Nghiên cứu vai trò của các gien liên quan đến khả năng chống chịu lạnh ở ngô: Quá trình biểu hiện và trình tự vùng promoter của các gien này

Bằng kỹ thuật PVR-CDNA Select Subtraction (hay còn có tên gọi khác là SSH- Supperssion Subtractive Hybridization) tác giả đã phân lập được 18 gien có biểu hiện cao trong điều kiện lạnh 6 độ C và 13 độ C. trong số 18 gien này, gien ZmCO16.1 có tần số xuất hiện rất cao (49%) trong thư viện cDNA.
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Phần III: Nghiên cứu vai trò của các gien liên quan đến khả năng chống chịu lạnh ở ngô: Quá trình biểu hiện và trình tự vùng promoter của các gien này31(3): 71-80 Tap chf SINH HOC 9-2009 ARTICLE 3: CHARACTERIZATION OF THE STRESS-INDUCED GENE ZMCOI6.1 IN MAIZE: EXPRESSION AND PROMOTER SEQUENCES THUY HA NGUYEN Institute of Agricultural Genetics, Hanoi,Vietnam JORGLEIPNER Institute of Plant Sciences, Zyiich, Switzerland ORLENE GUERRA-PERAZA University of Guelph, Ontario. Canada PETER STAMP Institute of Plant Sciences, Zyrlcli, SwitzerlandABSTRACT: Using cDNA subtraction technique, 18 cold stress responsive-genes were identified, amongthem a novel gene, ZmC016.1, whose function is still unknown. Analysis of the ZmC0I6.1 promotersequence revealed several conserved stress-responsive cis-acting elements. Further expression characterizationshows that ZmCOId.l is induced, in addition by cold, by other abiotic stresses such as drought and NaCI aswell as by signalling molecules such as ABA and SA. The results indicate that ZmC0I6.1 is a general stressresponsive gene. A possible regulation mechanism is presented where ZmC0I6.1 is alternatively splicedyielding two transcripts whose levels are changed upon different stress treatments. Furthermore the predictedZmC0I6.1 amino acid sequence and its homologue show high similarity with proteins in rice and Arabidopsissuggesting that it belongs to a conserved protein in plants. Cold-acclimation in plants involves multiple tolerance [8]. These results suggest that thischanges in morphology, metabolism such as transcriptional regulation mechanism is accumulation of abscisic acid (ABA) and conserved among several plant species. In salicylic acid (SA), changes in membrane lipid addition, CBF type transcription factors havecomposition, formation of compatible osmolytes been found in other plants although the function and production of antioxidants. These processes remains to be evaluated. However, there are alsoare accompanied by notable changes in the level indications of the existence of CBF-of various gene transcripts and proteins [16]. independent cold acclimaction [5]. GeneOur understanding of the molecular pathways in expression is regulated not only at thecold acclimation has changed dramatically with transcriptional level but can also be regulated bythe discovery of the C-repeat post-transcriptional events such as alternative(CRT)/dehydration-responsive element (DRE) splicing, translational and post-translationalbinding transcription factors (CBF) in the model modifications like phosphorylation [2].organism Arabidopsis thaliana. The CBFs bind Whilst the molecular pathways ofto CRT/DRE elements present in the promoter acclimation to low temperature are wellregions of many cold- and dehydration- understood for the model plant Arabidopsis [1,responsive genes such as cold-regulated (COR) 16], the knowledge about the molecular basis ofgenes [4, 17]. In these hnes, over-expression of cold-acclimation in maize is still rudimentary.Arabidopsis CBF induces COR gene expression Furthermore, low , temperature stress inin the chilling-sensitive tomato (Lycoperslcon Arabidopsis occurs at subzero temperaturesesculentum), resulting in protection against while maize growth is challenged already atchilling stress at 0°C and improved freezing temperatures below 20°C suggesting that 71divergent acclimation pathways might be separated by electrophoresis, using 2.0% Memployed. In order to characterize the molecular agarose gel, and monitored using Gel Doc 2000pathways induced in maize in response to cold (Bio-Rad Company, USA).stress, a previous study [12-14] identified The cDNA from the PCR amplification wasseveral nsovel genes, including ZmC016.1, cloned into the pDrive vector (Qiagen AG,whose transcript level increases after exposure Switzerland) and transformed into E. coli DH5Dto low non-freezing temperature. The aim of this ...