芝麻营养生长期枯萎病抗性鉴定技术研究

芝麻枯萎病是芝麻主要真菌病害之一,由尖孢镰刀菌芝麻专化型(FOS,Fusarium oxysporum f.sp.sesami)引起,主要在苗期和成株期发生。为精准评价营养生长时期(2对真叶~现蕾)芝麻种质对FOS菌株的抗性水平,试验分析了FOS菌液浓度、蘸根接菌时间、致病力等条件下芝麻种质枯萎病病症及病情指数变化规律,建立了营养生长期芝麻枯萎病抗性精准鉴定方法。结果表明,1×10^6 cfu/mL^5×10^6 cfu/mL浓度下,植株蘸根接菌处理1~2周即可发病;第4周样本枯萎病病情指数趋于稳定。上述方法反映不同芝麻种质营养生长期对FOS菌株的抗性水平以及不同FOS菌株的致病力。营养生长期芝麻枯萎病发生可分为0~4级共5个等级。采用上述鉴定方法对42份芝麻种质进行抗枯萎病鉴定结果显示,野生种Sesamum radiatum Thonn.ex Hornem.高抗枯萎病(DI=0),而S.angustifolium(Oliv.)Engl.高感枯萎病(DI=100)。40份栽培种资源中,高感(HS)种质比例极高(55%),抗病种质比例较低(27.5%)。研究结果为深入开展芝麻抗枯萎病遗传机理分析提供了技术支持。

An Evaluation Technique of Sesame Resistance to Fusarium Wilt Disease at Vegetative Stage

Sesame Fusarium wilt(SFW),which is caused by Fusarium oxysporum f.sp.sesami(FOS),is one of the main fungi diseases and primarily occurs at vegetative growth and flowering stages in sesame.In order to accurately evaluate the resistance level of sesame germplasm accessions to FOS strains during vegetative stage(from two-pair-leaves period to budding period),we analyzed the Fusarium wilt symptoms and the disease index(DI)variation of sesame germplasm accessions treated with several FOS strains,various concentrations of microconidia suspension and different time with treatment.A precise evaluation method of sesame resistance to Fusarium wilt disease during vegetative stage was established.Results indicated that Fusarium wilt symptom occurred in sesame plantlets 1 to 2 weeks later after inoculation with 1×10^6 microconidia/mL FOS suspension.The DI values became stabilized after 4 weeks.The resistance level of germplasm accessions and the pathogenicity of FOS strains were reflected using the above established method.Five grades of Fusarium wilt resistance from grade 0 to 4 for sesame during vegetative stage was proposed.The results derived from tests of 42 sesame accessions revealed that the wild species,Sesamum radiatum Thonn.ex Hornem.exhibited the stable high resistance to FOS(DI=0),while S.angustifolium(Oliv.)Engl.was highly susceptible(DI=100).Of the 40 cultivated accessions,57.5%samples were highly susceptible(HS),while 27.5%were showing highor medium-resistant.The findings supply the technological aids in further analyzing the genetic mechanism of sesame resistance to Fusarium wilt disease.