摘要
【背景】莲子草假隔链格孢是空心莲子草的重要生防菌,但长时间保存或继代培养会导致该菌株产孢量和致病性显著下降。【方法】通过对初始菌株回接、分离、纯化和鉴定相继获得复壮一代和二代菌株,分别在3、6、9d后对初始菌株、复壮一代和二代菌株进行产孢培养,比较其产孢量;同时比较分析了这3代菌株的液体发酵原液和1:10稀释液对空心莲子草的防除效果。【结果】获得了10株复壮一代和10株复壮二代菌株,20株菌对空心莲子草均有致病作用,且产生的分生孢子形态特征与初始菌株一致。与初始菌株相比,复壮菌株的产孢量显著提高且达到最大产孢量的时间显著短于初始菌株。其中,复壮二代菌株的孢子量是初始菌株的4.8倍,其次为复壮一代菌株,产孢量是初始菌株的4.1倍;复壮菌株达到最大产孢量的时间为3d,初始菌株为6d。复壮菌株一代和二代的原液对空心莲子草的致病性分别比初始菌株提高了4.65%和9.82%,1:10稀释液的致病性分别提高了25.79%和16.55%。【结论与意义】对长期保存或继代培养的空心莲子草生防菌复壮可显著提高其产孢量和致病性,对维持生防菌遗传性状的稳定性和提高对空心莲子草的防效具有重要意义。
[Background] Nimbya alternantherae has been considered an important biocontrol agent of Alternanthera philoxeroides.The capacity of conidia production and pathogenicity of the fungus had been reduced because of subculture or preservation for long periods in the lab,causing potential problems for its use in biological control projects.[Method]The rejuvenations of N.alternanthera SF-193,first and second generations were obtained by the process of inoculation,isolation,purification and identification.Conidial production of the initial and the rejuvenated strain was investigated after conidial cultivation for 3,6,9 days.The efficiency of A.philoxeroides treated by the initial and the rejuvenated strains was evaluated in the field.[Result]Ten rejuvenated first generations and ten second generation isolates were obtained.All of the rejuvenated isolates could cause foliar and stem necrosis of A.philoxeroides and the morphological character of conidia of rejuvenated isolates were the same as that of the initial isolate.Compared to the initial isolate,the conidial yield of rejuvenated isolate increased remarkably,and the time to peak conidial yield of rejuvenated isolate was shortened sharply.The rejuvenated second generation showed the highest conidial yield and was about 4.8 times more likely to produce conidia than the initial isolate.The times to peak conidial yield between the initial and rejuvenated isolates were 3 and 6 days,respectively.Under field conditions,the level of disease severity of A.philoxeroides by mycelia-blended suspensions of first generations and second generations without dilution ware increased by 4.65% and 9.82% and also by 25.79% and 16.55% after mycelia-blended suspensions diluted 1：10（V/V） with water,compared to the original isolate.[Conclusion and significance]It is important to sustain the genetic stability of N.alternanthera SF-193 and improve the efficiency of bio-control isolate against the weed by periodically rejuvenating the fungal isolates which were sub-cultured or preserved for long periods in the laboratory.
出处
《生物安全学报》
2011年第4期344-348,共5页
Journal of biosafety
基金
国家863项目(2011AA10A206)
关键词
空心莲子草
莲子草假隔链格孢
复壮
产孢
致病性
Alternanthera philoxeroides
Nimbya alternantherae
rejuvenation
conidia production
pathogenicity
