Changes Of Alternative Splice In Arabidopsis Thaliana Grown Under Different CO₂ And O₃ Concentration

DNA is firstly transcribed into pre-mRNA,and pre-mRNAs can remove different introns to obtain different mature mRNAs.This process is called alternative splicing(AS).It's an important post-transcriptional regulation mechanism that is essential for enriching the class of proteins,regulating gene expression levels and tissue-specific expressions.Studies have shown that plant's AS pattern is significantly affected by external stresses,and it can rapidly regulate the abundance and the function of stress response elements in plants.Both CO2 and O3 are major greenhouse gases,with a major impact on ecosystems and agricultural production.In recent years,the concentration of CO2 and O3 in atmosphere has continued rising.Many studies have examined the effects of elevated CO2 and O3 concentrations on plants and the corresponding response mechanisms.However,there is little researches focusing on how the plants AS pattern responds to the changes of CO2 and O3 concentrations.In this paper,model plant Arahidopsis thaliana was used as the research object.Two batches of A.thaliana RNA-seq sequencing data were downloaded from NCBI public database:(1)RNA-seq sequencing data generated by A.thaliana grown at low CO2 concentration(1 50 ppm)and high CO2 concentration(500 ppm);(2)RNA-seq sequencing data generated by A.thaliana grown under normal atmospheric O3 concentration and high 03 concentration(350 nL L-1).Then using bioinformatics tools to identify AS events and analyze changes in these events in different experimental group samples.The research results are as follows:(1)By analyzing the RNA-seq data of A.thaliana grown under different CO2 concentrations,121,463 AS events were identified in low-concentration C02 samples,and 122,174 AS events were identified in high-concentration CO2 samples.As CO2 concentration increased,the number of AS events in A.thaliana also increased.A total of 345 differential expression(DE)genes and 239 differentially alternative spliced(DAS)genes were identified by differential analysis.And the expression abundances of most DAS genes did not change significantly.Functional analysis showed that the enriched GO terms of DE genes and DAS genes were different,the DAS genes was mainly related to functions such as 'cellular response to stress' and 'cellular response to DNA damage stimulus'.(2)By analyzing the RNA-seq data of A.thaliana grown under different O3 concentrations,5,844 AS events were identified in the control group,and 6,326 AS events were identified in high-concentration O3 samples.As O3 concentration increased,the number of AS events in Arabidopsis also increased.A total of 188 differential expression(DE)genes and 349 differentially alternative spliced(DAS)genes were identified by differential analysis.And the expression abundance of most DAS genes did not change significantly.Functional analysis showed that the enriched GO terms of DE genes and DAS genes were different,and the DAS genes was mainly related to functions such as 'response to salicylic acid' and 'response to freezing'.Comparing the results of DAS analysis of the CO2 group and the O3 group,I found that 20%of the DAS gene responding to CO2 also showed significant AS pattern changes in response to O3.suggesting that the regulation of AS may be one way that responses to CO2 and O3 changing,even atmospheric changes simultaneously.The results showed that the number of AS events and related genes' Alternative Splice patterns in A.thaliana were significantly affected by the changes of CO2 and O3 concentrations.Both DE genes and DAS genes were involved in responding to external stimuli.However,their main functions were different.So it is speculated that AS can serve as an independent mechanism for gene regulation in response to elevated CO2 and O3.