Physiological And Transcriptional Regulatory Mechanisms Of Silicon In Alleviating Cadmium Stress In Populus Euramericana Clone I-214

Nowadays,cadmium(Cd)pollution seriously affects the agricultural environment and sustainable development.Phytoremediation is one of the important potential techniques for remediation of cadmium contaminated soils.Silicon(Si),a beneficial element for plants,can enhance plant resistance to stresses,showing wide application prospect in phytoremediation.In this paper,the Populus euramericana clone I-214 was cultured hydroponically by Hoagland nutrient solution to study the effect of Si on the physiology and transcriptional sequencing of clone I-214 exposed to cadmium stress to reveal the mechanism of exogenous Si in alleviating cadmium toxicity in clone I-214.The main conclusions are as follows.(1)Applying exogenous silicon improved root activity,enhanced the absorption of water and nutrient by roots in clone I-214.And thought reduced the formation of reactive oxygen species and lipid peroxidation,increased the binding of soluble protein with Cd and the uptake of Cd in stems,to alleviate the toxicity of clone I-214 under cadmium stress.(2)The nonenzymatic antioxidant system may not be the main route that Si to alleviate the cadmium stress in clone I-214.(3)Differential expression genes are screened that pval<0.05 with Fold change>2 as a standard.In total,146 genes are showed that differential expression between Cd treatment and CK,among which there were 86 up-regulated genes and 60 down-regulated genes.In total,540 genes are showed that differential expression between Cd+Si treatment and Cd treatment,among which there were 214 up-regulated genes and 326 down-regulated genes.(4)The differentially expressed genes were analysed thought GO and KEGG enrichment in two groups,Cd/CK were major involed in heat shock protein 70,Small heat shock protein HSP20,Cytochrome P450 and thioredoxin,Cd+Si/Cd were major transcription factors were involed in WRKY,GRAS,DELLA,protein kinase and Calcium-binding EF-hand(one of the Calcium binding proteins).Quantitative Real-time PCR was used to confirm the gene function.The confirmation results and RNA-seq results are basically in agreement.(5)When the number of SNP and InDel events in controle was used as reference,the SNP events in Cd+Si treatment increased by 2.45%compared with Cd treatment,and the InDel events increased by 3.08%.In new transcript prediction,the new exons area accounted for 94.99%.Si may increase the incidence of SNPs and InDels events,as well as the generation of new exons area,as a way to alleviate the toxicity of clone I-214 under cadmium stress.