Exploring The Key Genes And Pathways In Response To Cd And Pb Stress In Arabis Paniculata Based On Transcriptome Sequencing

Soil and water are increasingly at risk of contamination from the toxic heavy metals lead（Pb）and cadmium（Cd）.Cd and Pb are highly toxic heavy metals and common soil pollutants,which are easily absorbed and accumulated by plants and transferred to animals through the food chain,bringing potential hazards to human and other animal health.Plants that can accumulate a large amount of heavy metals in the shoots are called hyperaccumulators.In the hyperaccumulators,heavy metals are mainly located in the stem and leaf epidermis tissues,which often contain a large number of vacuoles,and most of the heavy metals are accumulated in vacuoles.One hyperaccumulator,Arabis paniculata（Brassicaceae）,can tolerate and hyperaccumulate an array of heavy metals,such as Zn,Cd,and Pb.However,the mechanism by which A.paniculata tolerates heavy metals is still uncharacterized.In this study,A.paniculata was used as the experimental material.After being treated with Cd Cl₂and Pb Cl₂separately for 14 days,a total of 18 samples from the shoot and root were subjected to RNA sequencing（RNA-seq）,and the key genes and pathways for the co-response of Cd（0.25 m M）and Pb（2.50 m M）were found.In total,4,490 and 1,804 differentially expressed genes（DEGs）were identified in roots,and955 and 2,209 DEGs were identified in shoots,after Cd and Pb exposure,respectively.In roots,gene expression coresponded similarly to both Cd and Pd exposure,of which27.48%were co-upregulated and 41.00%were co-downregulated.Kyoto Encyclopedia of Genes and Genomes（KEGG）and Gene Ontology（GO）analyses determined that the DEGs were associated with and enriched in different pathways.The co-regulated genes were predominantly involved in transcription factors（TFs）,cell wall biosynthesis,metal transport,plant hormone signal transduction,and antioxidant enzyme activity.Many critical Cd/Pb-induced DEGs,such as HAI2,ABF3,YSL3,ZIP11,ABCC9,NRAMP4,EIN3,WRKY19,and WRKY40,were also identified.The gene ABCC9 was co-downregulated in root tissues but co-upregulated in shoot tissues.The co-downregulation of ABCC6 and ABCC9 in the roots prevented Cd and Pb from entering the vacuole,so it is possible that more Cd and Pb remained in the cytoplasm and were translocated to the shoots.However,the co-upregulation of ABCC9 in shoots results in vacuolar Cd and Pb accumulation,which may explain why A.paniculata is a hyperaccumulator.The creation of a protein-protein interaction（PPI）network facilitated the identification of key genes,such as PI4KG4,MPK1 and XLG2,which act to maintain cell wall and plasma membrane integrity.These results will help to reveal the molecular and physiological processes underlying tolerance to HM exposure in the hyperaccumulator A.paniculata,and aid in future efforts to utilize this plant in phytoremediation.