Identification Of The Interaction Between Rice Black-Streaked Dwarf Virus P7-2 And Rice Proteins OSK And GID2

Rice black-streaked dwarf virus(RBSDV)is the pathogen of rice black-streaked dwarf disease and maize rough dwarf disease.It could cause severe plant phenotypes including growth stagnation,incomplete root,and dwarf.The function of nonstructural protein P7-2 of RBSDV encoded from the second ORF of S7 remain unknown.Our previous studies demonstrated that P7-2 could interact with the SKP1 which was the key factor of the SCF ubiquitin complex.The purposes of current study are to clarify the role of P7-2 in the formation of the ubiquitin complex and the potential interactions of P7-2 with some plant proteins.There are several different members in the SKP protein family of rice(OSKs).To study the interaction of P7-2 with different OSKs,we firstly cloned 25 OSKs with the homology cloning method,then detected the interactions of P7-2 with OSKs via yeast two hybrid system.The results shown that the P7-2 interacted with 8 OSKs with various intensity.The interactions of P7-2 with OSK1,OSK5 and OSK20 were then confirmed via co-immunoprecipitation(Co-IP),in vivo.The results obtained in yeast three-hybrid assay shown the interactions among P7-2,OSK1/5/20,and OsCUL,which implied that P7-2 may form the SCF-like complex by interacting with OSK-OsCULl.Furthermore,it was found that P7-2 could interact with GID2s of rice and maize through both yeast two hybrid and Co-IP test,and the P7-2 N-terminal was the key region in P7-2-GID2 interaction.GID2 could also interact with OSK5 and OSK20.Based on the results above,we speculated that P7-2 interacted with OSKs and CUL1 to furtherly form the SCF-like complex,and interfered the interaction between GID2 and OSKs to impair the formation of SCFGID2 complex which could recognize and digest the SLR1.Since the F-box protein GID2 is a key protein in gibberellin response pathway and plays an important role in recognizing the negative regulatory factor-DELLA protein,it is possible that the SCF-like complex composing of P7-2 and OSK1/5/20 capture and induce the degradation of GID2 through ubiquitin system,which repress gibberellin response pathway and lead to the dwarf's symptoms of infected plants.In addition,in order to furtherly study the function of the according genes,we had also done other primary investigations,like detecting the expression of the related interaction proteins in plant,studying the function of P7-2 and OSK1,and exploring the interaction relationships between the other virus proteins and the OSK proteins.So far we have obtained some preliminary results.