Mechanism Of The Transcriptional Regulation Of StSID2 By StRVE1 In Copper Ions-mediated Potato Late Blight Resistance

Late blight caused by Phytophthora infestans is one of the important diseases in agricultural production,which seriously affects the yield and quality of potatoes,and the control of late blight has become an important research target in potato production and breeding.At present,the prevention of late blight requires large doses and high-frequency spraying of chemical fungicides,and the effect of fungicides is gradually reduced or even ineffective due to the continuous evolution of pathogenic bacteria.Copper-based fungicides have been widely used for the control of diseases such as late blight for more than 130 years and are still the only designated drugs for organic potato production in European countries.Although some pathogenic microorganisms have been found to be resistant to copper,copper spraying preparations can still be effectively controlled.Previous laboratory studies have found that copper ions can regulate ethylene(ET)and salicylic acid(SA)signaling to stimulate Arabidopsis thaliana disease resistance,and the analysis of ET to improve resistance to potato late blight by inhibiting abscisic acid(ABA)synthesis,but the molecular mechanism of how copper ions stimulate plant disease resistance through SA is unclear.In this project,the differential genes of copper ion stimulation potato against late blight were functionally mined,and the mechanism of action of the St RVE1-St SID2 transcription module regulating SA in copper ion anti-late blight was discovered,and the specific results are as follows:(1)Copper sulfate treatment of potatoes at dawn and dusk respectively found that copper ions could improve the disease resistance of potatoes to late blight,but copper sulfate treatment made potatoes significantly more resistant to late blight at dawn than at dusk,which proved that the disease resistance response excited by copper ions was regulated by circadian rhythm.Retrieval of potato transcriptome data revealed that the transcription of St RVE1,a gene related to circadian rhythm,was activated by copper ions.(2)In order to explore the role of St RVE1 in resistance to late blight in potatoes stimulated by copper ions,transgenic potatoes with overexpression of St RVE1 were prepared.The incidence area,disease index and mycelial biomass of transgenic plants inoculated with Phytophthora infestans were significantly lower than the wild type.Potatoes that used virusinduced gene silencing(VIGS)to inhibit St RVE1 gene expression were more sensitive to late blight,and lost response to copper ions,indicating that St RVE1 positively regulated potato disease resistance to late blight.(3)The transcription level of the SA synthesis gene St SID2 and the content of SA in St RVE1 transgenic plants were significantly higher than the wild type.Further truncated analysis of the promoter of St SID2 showed that St RVE1 could activate the reporter expression driven by the promoter of St SID2,and the-818 to-500 regions of the promoter of St SID2 played an important role.This section contains an evening element AATATAT.(4)There are two transcripts of St SID2 gene in potato,and the transcription level of St SID2-1 is lower than that of St SID2-2.The overexpressed transgenic potatoes of these two transcripts were prepared.Compared with the wild type,St SID2-1 transgenic potatoes were more susceptible to late blight,but St SID2-2 transgenic potatoes were more resistant to late blight.Potatoes silenced St SID2 gene by VIGS technique were more sensitive to late blight,and lost response to copper ions.In conclusion,St SID2-2 positively regulates potato resistance to late blight,while St SID2-1 negatively regulates potato resistance to late blight.(5)The transcription level of SA signaling pathway related gene PR1 b in St SID2-1transgenic plants was significantly decreased by real-time quantitative PCR detection,while the transcription level of PR1 b in St SID2-2 transgenic plants was significantly increased.Further study showed that exogenous SA treatment enhanced potato resistance to late blight.In summary,this study found that copper ions regulate St SID2 transcription by activating the transcription factor St RVE1,promote salicylic acid synthesis,and enhance potato resistance to late blight,revealing the mechanism of the St RVE1-St SID2 module in copper ion induced potato resistance to late blight.