In Search Of The Molecular Mechanism Of Potato Responses To Thaxtomin A Through Proteomic Analysis

Thaxtomin A(TA)produced by Streptomyces scabies is one of the major causing phytotoxins,which induces the formation of scabs on potato tubers.In current study,isobaric Tags for Relative and Absolute Quantification(iTRAQ)method was employed to identify the proteomic changes between potato leaves treated with TA and mocks.Diploid potato Solanum tuberosome phureja DM 1-3 was chosen as experimental material because its genome sequencing had been completed,which facilitate the bioinformatics analysis.To our knowledge,it is the first proteomic attempt to investigate the mechanism of plant responses against TA.The significance of this paper is that we proved that the TA treatment could promote the accumulation of Reactive Oxygen Species(ROS),finally causing cellular damage to plant cells.Based on these observations,we also propose a novel working model which interprets how plants respond to TA treatment at molecular level.The specific experimental results are as follows:The first describes the establishment of TA-potato interaction system using potato and Arabidopsis leaves.The results showed that the treatment with 10μM TA for 24h could effectively induce the response of plants to the toxin,however could not lead to the leaf death.The second includes the application of iTRAQ techniques on potato leaves and bioinformatic sududy of proteome results.Functional annotation,classification analysis and metabolic pathway analysis of different expressed proteins(DEPs)revealed that the major group of DEP under TA treatments were stress or defense-related proteins,of which antioxidant stress-related proteins accounted for the largest proportion with 25 percent.The third covers the validation test and physiological experiments.qRT-PCR experiments of selected genes encoding DEP were performed,and the results suggested the gene expression data was largely in good agreement with iTRAQ data.The DAB staining and antioxidant enzyme activity detection experiments were conducted to explore the relationship between ROS and TA treatments.The results showed that TA treatment could induce the ROS bursts in potato leaves,which might contribute to the progression of potato common scab.