Auxin Response Factor CsARF8-2 Response To Drought Stress In Tea Plant

In recent years,drought occurred frequently in tea gardens in China which caused adverse effects on tea quality.Therefore,it is necessary to study how tea plants respond to drought stress.Auxin is an important plant hormone.A growing number of studies have found that it plays a role in drought response.And as an important transcription factor of auxin signal transduction pathways,whether it is necessary for auxin response factors to respond to tea plants drought stress and what role it plays are of great significance.Based on the results of genome and transcriptome sequencing,the cDNA and promoter sequences of tea plant auxin response factor CsARF8-2 were cloned.The protein sequence encoded by CsARF8-2 was predicted by bioinformatics analysis.Tow-year-old potted cutting tea seedlings of four cultivars were used for natural drought treatment,and evaluation of the drought resistance of tea varieties was evaluated by method of subordinate function.The relative expression of CsARF8-2 during drought stress was studied by real-time fluorescent quantitative PCR.Tissue specific expression analysis of CsARF8-2 was detected by real-time fluorescence quantitative PCR and histochemical staining.Subcellular localization was determined by observing GFP fluorescence.Functional verification was conducted by overexpression of CsARF8-2 in model plant Arabidopsis thaliana.The main research findings are as follows:1.The cDNA and promoter sequences of tea plant auxin response factor CsARF8-2 were cloned.Bioinformatics analysis showed that the open reading frame of CsARF8-2 was 2496 bp in length,encoded 831 amino acids,and had typical B3-DBD,Auxin_resp and CTD domains.The predicted results showed that the promoter contained hormone response elements,stress response elements and light response elements.2.The drought resistance of four varieties was comprehensively evaluated by subordinate function value,and the results showed that Longjing 43> Ningzhou 2> Zhuyeqi> Baiye 1.Real-time fluorescent quantitative PCR results showed the relative expression of CsARF8-2 gradually decreased with prolongation of drought treatment time.Moreover,the stronger the drought resistance of tea cultivars,the more obvious the decline in gene expression.3.Tissue-specific expression results showed that CsARF8-2 was expressed in various tissues of tea plant,among which the highest expression in stem,followed by flower,bud and leaf,and the lowest in mature leaves.The expression vector of proCsARF8-2::GUS was transferred into wild Arabidopsis thaliana,and histochemical staining showed that the growth point of the transgenic material,the main vein of young leaves,lateral root tips,flower buds and fruit pods were all expressed.4.ABA sensitivity analysis and drought stress showed that there were no significant difference between wild-type and overexpression lines.It may be caused by the functional redundancy of ARF family gene.