The Response Of Arabidopsis Ethylene Signal Deficient Mutant To Cadium Stress

Industrial development and natural resource consumption lead to environment pollution with an increasing trend.Heavy metal pollution is not only harmful to human health,but also induces damage to plants.Cadmium(Cd)is a major heavy metal pollutant.Ethylene is a kind of natural plant hormones,plays an important role in plant flowering,fruit ripe,ageing,also regulates plant adaptation to changing environments.In order to address the regulation role of ethylene signaling in plant response to Cd stress,we used Arabidopsis ethylene signal deficient mutant(ein2-1)as experimental material compared with wild-type plants in physiological and biochemical metabolisms,proteomics,and genetic expressions.The main results as follow.Cadmium treatment(100 ppm)induced plant growth retardation as indicated by plant fresh weight and dry weight,with a greater degree in wild-type(WT)plants than ein2-1 plants.This suggested that the deficiency of ET signaling increased plant tolerance.In other words,ET signaling promoted plant sensitiveness to Cd stress.Cadmium stresses caused plant oxidative stress damage as shown by ion leakage and malondialdehyde contents.This was supported by leaf staining,such as nitroblue tetrazolium(NBT)staining(for superoxide anion)and DAB staining(for hydrogen peroxide).Cadmium stress increased the contents of tested plant proline,soluble sugar and soluble proteins,which could enhance plant tolerance to Cd-induced oxidative stress damage.Cadmium stresses increased plant antioxidant capacity,such as the activities of superoxide dismutase(SOD)and peroxidase(POD),especially in ein2-1 plants.The proteomics study showed that Cd stress significantly altered protein expression level.There were several hundred kinds of proteins to be either up-regulated or down-regulated.These differentially expressed proteins were involved in a variety of biological processes,such as the ribosome,endoplasmic reticulum,RNA transport,amino acid synthesis,endocytosis,spliceosome,starch and sugar metabolism,purine metabolism,mRNA related process,phenylalanine pathway,RNA degradation,fatty acid metabolism,carbon metabolism,pyrimidine synthesis,ubiquitin related metabolism,synthesis of unsaturated fatty acids,amino acids and RNA metabolism,GSH metabolism,oxidative phosphorylation,glycolysis and sugar dysplasia and other process.We analysed the expression patterns of some selected genes,and found that the results of gene expression were essentially in line with the data of proteomic data.