| RBSDV(Rice black-streaked dwarf virus)and RSV(Rice stripe virus)are two common viruses which caused great loss in rice and other crops,and some efficient and feasible revention measures will help us improve our food production safety.Although previous studies found that melatonin(MT)and nitric oxide(NO)can induce a variety of plant resistance to pathogens,the detailed mechanism about interaction of rice-virus remains unclear,for most researches concentrated on bacteria,fungi or nematode in dicotyledonous plants.Besides,salicylic acid(SA)is a plant hormone which is widely recognized relevant to disease,and MT and NO can induce plant resistance to bacteria separate or synergic manner,but it is unclear whether there is any interaction between virus and them.For the problem mentioned above,we found that:1)SA is participated in the NO triggered rice resistance to RBSDV;2)NO can be induced by melatonin and promote rice resistance to RSV.All results showed that:(1)The rice resistance to RBSDV is relevant to the content of NO and SA.Inducing the synthesis of NO and SA content and subsequent expression of resistance genes,Sodium nitroprusside(SNP)can reduce the disease rate in a concentration dependent manner.By contrast,a NO scavenger(cPTIO)can reduce NO content and reverse this process.In addition,free-SA in various treatments is positively correlated with NO content,and induced two resistance genes,OsPR1b and OsWRKY 45.Similar results were also observed by application of S-Nitrosoglutathione(GSNO)and NONOate,another two NO donors,and the pretreatment with Benzothiadiazole(BTH)proved the SA function to disease resistance.Besides,genetic analysis was also carried out to support above results.(2)The rice resistance to RSV is relevant to the MT and NO content.Inducing the synthesis of NO and subsequent expression of resistance genes,both of them can reduce the disease rate in a concentration dependent manner.By contrast,cPTIO can reduce NO content and eliminate the MT impact on disease condition,which may suggested that NO participate in the process of rice response to RSV infection triggered by MT.Subsequent results revealed that RSV stress can induce the synthesis of MT and NO,and NO may located in the downstream of MT.Taken together,these results indicate that MT can induced rice resistance to RSV by NO.In short,with the data from pharmacology,molecular and genetics experiment,we demonstrated that SA involved in NO triggered rice resistance to RBSDV and MT can induce rice resistance to RSV through NO. |
