Adzuki Bean Rust Resisatance Elicitor Screening And Induced Disease Resistance Mechanism Study

Adzuki bean rust,caused by the Uromyces vignae,is one of the most serious diseases on adzuki bean production.Accompany with the plant area increasing of adzuki bean,a key problem was how to prevent the rust occurrence for improving the yield and quality of adzuki bean.Presently,fungicide was still the most commonly method for disease control,but problems including drug-resistant and environmental pollution were still the main drawback of chemical control.Accordingly,plant resistance utilization was considered as most economical and effective method for disease control.Numerous studies showed that exogenous elicitors can effectively improve the plant resistance against various diseases.Therefore,in the present study,adzuki bean rust resistance elicitors screening and the resistance induction mechanism analysis were conducted.The results were as followed:1.Influence of salicylic acid(SA),melatonin(MT),benzothiadiazole(BTH)and methyl jasmonate(MeJA)on urediospore germination was detected by using slides hanging drop method.And no significant inhibition of urediospore germination was observed that expose to these substances.Subsequently,induced resistance effects of the 4 substances were tested using artificial inoculation method.Results showed that 0.2 mM MT was the best elicitor for inducing rust resistance with a control efficiency reach to 61.05%.Additionally,the best induction interval and duration of MT was 48 h and 240 h,respectively.The control efficiency of the other three elicitors 0.06 mM BTH,2.00 mM MeJA and 2.00 mM SA were 26.57%,36.78% and 38.06%,respectively.2.Activity of resistance related enzymes including PPO,POD,CAT,APX and SOD after MT treated with or without challenge inoculation were investigated among different infection stages on different resistant cultivars.The results show that the activity of PPO,POD and APX were significantly induced by MT treated either in resistant or susceptible cultivars that inoculated with rust.Both of the responsive time and level of these enzymes were higher than the non-induction treatment that inoculated.Moreover,activity of CAT reach to the highest level at 48 h after inoculation either in the resistant or susceptible cultivars with MT treated,however,the responsive level in MT treatment was significantly higher than the non-induced treatment.While SOD activity had no significant variations among different samples.These results revealed that exception of SOD,the other enzymes including PPO,POD,CAT and APX might be play an important role in the induced resistance.Thereafter,to better understanding the difference of the injury degree,the concentration of MDA in different samples were investigated.The results showed that the MDA concentration represent a decreased tendency in different samples that exposed to MT with or without inoculation,while in samples without MT treated the MDA content were increased after 24 h inoculation both in the resistant and susceptible cultivars.It is indicated that the MT has important contribution in protecting plants from damage caused by rust infection.3.Gene expression profiling of the pathogenesis related protein including CHI(Chitinase),GLU(?-1,3-glucanase),PR1(pathogenesis related protein1)and PR5(pathogenesis related protein5)in different samples were conducted using quantitative real time PCR.In susceptible cultivar,the relative expression level of the CHI gene was significantly increased at 24 h after inoculation(hai)with MT treated,while in the sample without MT treated the CHI gene increased to maximal levels until to 48 hai.Resistant cultivar are similar to susceptible varieties.In susceptible cultivar,the relative expression level of the GLUgene was significantly increased at 48 h after inoculation(hai)with MT treated.The PR1 gene and PR5 gene were significantly higher than untreated without MT treatment at the time of 48 h,and the results showed that the expression of PR1 gene and PR5 gene was significantly higher than that without MT treatment disease resistance genes showed a significant upward trend,so that plants produce stronger disease resistance.