Race Identification Of Fusarium Oxysporum Causing Mung Bean Wilt And Screening Of Resistance Resources

Mung bean[Vigna radiata(L.)Wilczek]is one of the most important grain legumes in China.Fusarium wilt,caused by the fungal pathogen Fusarium oxysporum,is a severe soil-borne disease and seriously limits the yield of mung bean in China.Deployment of resistant cultivars is the most economic and effective way to control this disease.1.Build a method for evaluation of resistance to Fusarium wilt in mung bean.the main factors affecting resistance phenotype including inoculation method,plant development stage,inoculum concentration,inoculum treatment time and inoculated plants incubation temperature,were comparatively analyzed.In conclusion,the root cutting technique was the optimal inoculation method.The seedling of mungbean at 2 leaf age was suitable to inoculation with pruned roots dipped in spore suspension of 10~5~10~6 spore/mL for 2 min.Inoculated plants should be incubated at 25?.The survey time of disease scoring can effectively shorten experimental period at 14 days after inoculation.This method is rapid and effective for evaluation of mungbean resistance to Fusarium wilt in controlling condition,which will provide technical support for mung bean germplasm resistance screening and breeding program.2.Identify pathogenic variability among F.oxysporum isolates on mung bean and develop a set of differential cultivars.Firstly,105 mung bean cultivars were screened against a virulent isolate F08.Based on the different genetic background and different resistance phenotype,we selected 11 as candidate differential cultivars for differanriating race of the pathogen.Then,candidate differential cultivars were tested for resistance phenotype by 25 isolates.The result showed that different isolate×cultivar interaction pattens cause highly significant difference on Disease index value.Based on interaction patterns,6 cultivars were selected as a set of differential host and Jilv 7 was selected as susceptible control.3.Identify physiological race of F.oxysporum causing mung bean wilt.The set of differential cultivars were used to identify virulence type of 84 isolates.The results show that 84 isolates were divided into total 12 races based on their different virulence patterns.Among 12 races,Races 3 were the most predominant among the sampling collections with 19 isolates,account for 22.7%and distributed in Jilin,Inner Mongolia,Shaanxi,Shanxi and Henan,that is predominant race.Race 5 and Race 11 are most strongly virulence.Race 5 was virulent on all cultivars except for VC3890A;Race 11 was virulent on all cultivars except for Yulv 2.Race 0 has lowest virulence and was avirulent on all differential set cultivars.Except to isolates of race 5 was only identified in Jilin province,others races coexisted in many areas.This result showed race distribution was not related on geographical origin.4.To differentiate the races at DNA level,the SIX6 and SIX11 gene of F.oxysporium were analyzed in the mung bean isolates.Results show that the SIX6 and SIX11 gene-specific primer were amplified to a target band in all isolates except for a non-pathogenic isolate,which revealed that SIX6and SIX11 gene could associate with pathogenicity of F.oxysporium causing mung bean wilt.But,both them can't differentiate the mung bean isolates,which showed that SIX6 and SIX11 gene can't be suitable for distinguishing the physiological races.5.To screen the resistance cultivars,433 mung bean germplasms and 544 strains of 19 cultivars were identified by inoculating isolate F08.Results show that46 mung bean germplasms were resistant,account for 10.6%,and among 544 strains,54 strains selected from 14 cultivars were homozygously resistant.This result can be useful to study on inheritance of the resistance and map of the resistance gene in mung bean.