Cloning,Identification And Expression Analysis Of ARGONAUTE Family In Potato

Argonaute proteins are the core proteins of RNA induced silencing complex(RISC),which participate in various RNA silencing pathways with different small RNA in plants,and play an important role in plant growth and development,resistance to stress and antivirus defense.In this study,14 StAGOs genes were identified and cloned in potato by bio-informatics method,and their gene functions were explored by expression analysis preliminarily.The main results are as follows:1.14 potential StAGOs genes were found by bio-information method.encoding475(StAGO4-3)to 1127 amino acids(StAGO1-2),respectively.These StAGOs genes were distributed on the potato chromosome 1,2,3,6,7,9,and 12.Analysis of the conserved domain revealed that StAGO4-3 lacks PAZ domain,probably pseudogenes,and the remaining 13 StAGOs genes contained typical conserved domains of AGO protein,indicating that they were indeed members of the AGO family.2.Specific primers were designed according to the sequence information of the StAGOs gene transcript in the NCBI and PGSC databases.The full-length cDNA sequences of 14 StAGOs were cloned in potato.Sequencing results showed that the sequence similarity between the cloned sequence and the database was from 83.15%(StAGO2-2)to 99.59%(StAGO1-2),while that of encoded proteins ranged from66.22%(StAGO2-2)to 99.73%(StAGO1-2).The phylogenetic tree was established by cloned StAGOs,AtAGOs and SlAGOs.The result showed that StAGOs can be divided into 3 clades: Cluster1 contains StAGO1-1,StAGO1-2,StAGO5,StAGO10-1 and StAGO10-2;Cluster 2 contains StAGO2-1,StAGO2-2,StAGO2-3 and StAGO7;Cluster3 contains StAGO4-1,StAGO4-2,StAGO4-3,StAGO4-4 and StAGO16.3.Expression analysis showed that StAGOs gene could be expressed in roots,stems,leaves,flower buds and tubers,but the expression of genes in different tissues was significantly different.The expressions of StAGO1-1,StAGO4-1,StAGO4-2,StAGO4-4,StAGO5 and StAGO7 were higher in the flower buds than in other tissues.StAGO2-2,StAGO2-3 and StAGO10-2 were mainly expressed in roots and stems.Then gene expression analysis under different stress treatments showed that StAGO2-3,StAGO5,StAGO10-1 and StAGO16 could respond to low-temperature,high-temperature or salt stress.Analysis of the expression of StAGOs gene after inoculation with PVY viruses in potato plants showed that StAGO1 and StAGO2 were significantly up-regulated during the systemic infection of PVY virus,indicating that StAGO1 and StAGO2 might be the main antiviral AGO proteins of potato.The interference expression vectors of StAGO1 and StAGO2 were constructed to carry out genetic transformation of potato in order to obtain the transgenic lines to further verification of its antiviral function.