| Natural weather disasters have a great restraint on the development of agriculture and forestry.A series of physiological and biochemical metabolic reactions will occur after trees are subjected to abiotic stress,which will affect the growth and development of plants and their morphological and structural changes in severe cases.Ethylene response factor(ERF)is a unique transcription factor in plants and plays an important role in environmental stress response.It plays an important role in abiotic stress resistance by regulating transcription factors to control the expression of downstream genes.Betula platyphylla,a species of birch in the Betulaceae family,with straight tree body and smooth white bark that can peel off,is one of the important precious hardwood species in China.Its wood is widely used and has important economic and ecological value.It has been highly loved by forest breeders.B.platyphylla can grow in extreme weather in Northeast China,and has a strong ability to withstand low temperatures.However,the mechanism of its response to low temperature is unknown.Understanding the molecular mechanism of low temperature resistance of B.platyphylla has theoretical significance for improving the low temperature resistance of other species.In this paper,through preliminary laboratory analysis,it was found that BpERF98 gene belongs to the ERF subfamily of AP2/ERF transcription factor family,and its gene expression level was significantly upregulated after low temperature stress.The research is as follows:(1)The function of BpERF98 gene was analyzed,the fusion expression vector of p BI121-BpERF98-GFP was constructed,and it was transiently transformed into onion epidermal cells.The results showed that the expression product of this gene was located in the nucleus.(2)Online data analysis of the promoter sequence of BpERF98 gene found that it contained a large number of cis-acting elements,including core basic elements of initiation and stressresistant elements,such as TATA box,CAAT box,ABRE,CGTCA,and other elements.We can speculate that BpERF98 plays an important role in response to abiotic stress.The B.platyphylla plants specificity of birch was analyzed by Quantitative Real-time PCR experiment,and the promoter vector was constructed for GUS staining experiment.As a result of the Quantitative Real-time PCR experiment were consistent with the results of the GUS staining experiment,and the results showed that the gene was mainly expressed on leaves.(3)Transcriptome sequencing of B.platyphylla plants overexpressing BpERF98 revealed a large number of differentially expressed genes.GO enrichment analysis of differentially expressed genes revealed that a large number of genes were associated with pathways such as response to stimuli,biological regulation,cellular processes,and metabolic processes.Overexpression of BpERF98 can enhance the expression of related stress resistance genes.(4)The BpERF98 gene was cloned from birch leaves,and the transgenic birch plants overexpressing BpERF98 were obtained by Agrobacterium-mediated method.Physiological indexes of transgenic B.platyphylla and wild-type B.platyphylla under low temperature,freezing injury and salt stress were measured and differences were analyzed.The analysis showed that under low temperature and salt stress,the malondialdehyde content and relative conductivity of transgenic B.platyphylla were lower than those of wild-type lines,and the increase of SOD and POD enzyme activities of transgenic lines was significantly higher than that of wild-type lines.These results indicate that overexpression of BpERF98 gene can increase the contents of SOD and POD enzymes in B.platyphylla cells during low temperature and salt stress,maintain the stability in cells and improve its resistance ability,which provides theoretical basis and resources for studying the molecular mechanism of formation. |
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