The Study Of Lncrna Expression And Function Under Cd Stress In Rice

Recently,the pollution of heavy mentals in our country is very serious.The water and soil pollution induced by heavy mentals have effected the growth and development of plant and human health.Currently,cadmium(Cd)is one of the serious heavy metal pollution,and is easy to accumulate in a variety of crops,thereby causing damage to human health.Rice(Oryza sativa L.)is an important crop in China.Cd seriously affected the growth and yield of rice.So,mastering the mechanisms of rice and reducing the accumulation of Cd in rice,has important and far-reaching significance for food safety.The rapid development of high throughput sequencing reveals the complexity and universality of eukaryotic transcription.The noncoding RNA(ncRNA)known as a "dark matter" has been confirmed to effect on numerous biological processes.Among them,the RNA with the length more than 200 nucleotides but have no or few protein-coding ability called long-non-coding RNA(lncRNA).In animals,long nocoding RNA have been proved to participate in a variety ways,and the model plant Arabidopsis thaliana has also been proved to have important roles of the regulation in gene expression in eukaryotes.Whether it is associated with hea'vy metals has never been reported.Previously,we treated the roots of rice with 10 ?M and 100 ?M Cd,then through bioinformatic analysis we screened 93 lncRNA associated with Cd.We found 15 of the identified lncRNAs differentially expressed under Cd stress,including nine induced and six inhibited by Cd.With RNA-seq data,we identified the IncRNAs on the whole genome level related to Cd and analysed their sequence,chromosome distribution and the repeatability.The length of plant lncRNA is usually less than 1000 bp,but the IncRNA we analysed is between 1000-2000 bp.Even thougth they uniformly distributed in each chromosome,they had lower repeats than mRNA.Furthermore,we used Nipponbare as the material to study the lncRNA expression under Cd concentration gradient and time gradients and found different lncRNA showed different expression patterns:(1)With the Cd concentration increasing the expression changes gradually;(2)The expression of lncRNA was less changed under different Cd concentration treatment;(3)The expression differences are significant at high concentration.The reason maybe different lncRNA have different reponse to different Cd.Under 10?M Cd treatment at different times,the expression of lncRNA change differently with the time.Then,we analyzed the expression of lncRNA in different tissues of rice by semi-quantitative,results showed that lncRNA only expressed in the root but not in stems or leaves.This means that lncRNAs have tissue-specific expression patterns.And,this may be that the roots uptake and transport Cd firstly.As reported,the lncRNAs with lower expression have higher specificity.In the study of IncRNA function,we cloned IncRNA(XLOC-001126)by the method of 3 'and 5' RACE.At the same time,we used bioinformatics to predict the endogenous target mimes of miRNA.We found that XLOC-001126 and XLOC-025994 are endogenous target mimics of mir162a and mir156k.By generating XLOC-001126 and XLOC-025994 overexpression transgenic plants,we detected the expression of miRNA and its target gene to verify the relationship between them.We found that a slight decrease in the expression of miRNA,and the increase of their target is not very significant,it may be that the impact of lncRNA on miRNA is not very remarkable.Correspondingly,target genes of miRNA did not chang significantly.