Identification And Function Of MiPEPs In Soybean Nodulation And Nitrogen Fixation

MicroRNA(miRNA)is a kind of small non-coding RNA with the length of 20～24 nt,which plays an important role in the regulation of plant growth and development.Recent studies have shown that some primary transcripts of miRNA(pri-miRNA)can encode short peptides,which are called miPEP(miRNA encoded peptide).In plants,miPEP mainly increases the expression of mature miRNA by promoting the transcription of corresponding pri-miRNA,so as to improve the regulation of miRNA on target genes.Glycine max and Rhizobium coexist to form root nodule,which can convert nitrogen in the air into nitrogen that can be directly absorbed and utilized by plants.Making full use of symbiotic nitrogen fixation in agricultural production will help to realize the weight loss and efficiency increase of chinese agriculture and promote the green and sustainable development of agriculture.This subject takes soybean as the research object,deeply excavates the possible miPEP in different tissues of soybean by combining miRNA and ribosomal imprinting sequencing technology,and verifies the function of some mipep in soybean nodulation and nitrogen fixation by molecular biological means.The specific research results are as follows:1.After 3 days of infection with Bradyrhizobium japonicum,1547 soybean miRNAs were identified,including 787 known soybean miRNAs,355 new members of the known miRNA family,and 405 previously unreported new soybean miRNAs.2.Through ribosomal imprinting sequencing of soybean root and leaf tissues,combined with the constructed soybean miRNA initial transcript database,560 miPEPs that may encode small peptides were excavated,of which 14 were significantly regulated by rhizobia infection.3.Through the transformation experiment of soybean hairy root,the function of 7 candidate miPEP was verified.The results showed that overexpression of miPEP-c and miPEP-h could significantly inhibit soybean nodulation,while overexpression of miPEP-b could significantly promote soybean nodulation.4.Through the analysis of transgenic roots,the experimental results show that miPEP-c,miPEP-h and miPEP-b all function by promoting their corresponding miRNAs.It was found that miPEP-b inhibited the expression of ARF16,the target gene of miRNA,by promoting the expression of miRNA-b,which provided important reference information for further understanding the molecular mechanism of miPEP regulating tumorigenesis.