Transcriptome Study Of The Electron Leakage From Siberian Iris Cells Induced By Lead

Recently,heavy metal contaminated soil is hot topic of environmental field,and phytoremediation is a widely accepted green remediation technology.In this paper,the emergent wetland plant Siberian Iris were selected using in phytoremediation,and the RNA-Seq was adopted to analyze different expression of genes.Further studied the metabolic pathway of Siberian Iris under the lead stress,the effects of lead induction on the expression of key genes in photosynthesis and respiration were deeply analyzed,especially the effect on the electron transfer of the photosynthetic and respiratory chains.The transcriptome sequencing technology was performed,and 44495628 original sequences were obtained.After assembly,299995 unigenes were checked.After denovo assembly and searching the assembled transcripts against Pfam,KEGG,String,Swisspro and NR database,Differential expression unigenes,GO analysis,KEGG analysis were performed.Consequently,158911 unigenes get functional annotation,and the annotation rate is 52.97%.According to the analysis of photosynthesis gene expression,it can be found that the gene about synthesis process of PSII,PSI,and cytochrome b6 f complex were influenced significantly,while the gene about synthesis of F-ATPase was not sensitive to lead induction.There were 16 key genes differentially expressed,including 12 sensitive genes and four stable expressed genes.The lead induction led to inactivation of gene about the synthesis process of Oxygen-evolving complex(OEC),and the leakage of electrons rose the level of active oxygen radical(ROS)in cells.As a signal transducer,the leaked electrons activate their self-defense system,thereby the expressions of pas A and pet F raised,and ROS levels were reduced.That also can promote the synthesis of new PSII damaged protein(mainly D1 protein),and OEC was repaired to ensure the smooth progress of photosynthesis.According to the analysis of respiratory gene expression,it can be found that the oxidative phosphorylation process had a significant response.There were 27 genes differentially expressed,which were in down-regulated and mainly related to the electron transfer in NADH dehydrogenase,cytochrome c reductase,and cytochrome c oxidase.The down-regulated expression blocked electron transfer in the respiratory chain and affected the transportion of protons from inside to outside of the thylakoid membranes,which resulting in leakage of electrons and causing the ROS level to rise.At the same time,the synthesis process of ATP synthetase β structure was blocked and the ability of ATP synthesis was reduced.The restricted energy supply would block the synthesis of substances in the oxidative phosphorylation process.