香蕉枯萎病抗性离体接种鉴定方法的优化

Modification of in vitro Bioassay for Screening Musa Species Against Fusarium oxysporum f. sp. cubense

前期研究明确了影响香蕉生根试管苗离体接种Fusarium oxysporum f.sp.cubense(Foc)进行抗病性鉴定的4个主要因素:产孢培养基、试管苗接菌前在MIS(Medium for interaction system)培养基上生长的时间、MIS培养基的组成、Foc菌株的致病力等。在此基础上,采用正交试验设计对离体接种鉴定方法进行优化。Logistic回归分析结果表明:影响发病最重要的因素是Foc菌株的致病力(P <0.001),其次是产孢培养基和MIS培养基的组成(P <0.05),试管苗接菌前在MIS培养基上生长的时间对鉴定结果也有一定的影响。上述4个影响因素的最优组合为用马铃薯葡萄糖水作产孢培养基,香蕉试管苗接菌前在MIS培养基上生长7 d,MIS培养基的组成为1/2MS不含有机物,接种菌株为Foc热带4号小种复壮3代菌株。分析得到的最优组合与验证试验的结果一致。

It was observed that the final disease severity was mainly affected by sporulation medium,growing time of banana plantlet on medium for interaction system(MIS)before in vitro inoculation,components of MIS medium,and pathogenicity of Fusarium oxysporum f. sp. cubense(Foc)tropical race 4(TR4)strain. The effects of the four factors on final disease severity were studied by using orthogonal experimental design. Logistic regression model analysis of data showed that pathogenicity of Foc TR4 strain was the most important factor(P < 0.001),followed by sporulation medium(P < 0.05),components of MIS medium(P < 0.05),and growing time of banana plantlet on MIS medium before in vitro inoculation. The optimum factor combination for rapid screening was the third-generation rejuvenated strain,potato dextrose water meduim,half-strength Murashige and Skoog salts without organic elements, and 7-day growth of banana plantlet on MIS before in vitro inoculation,which was consistent with the result of verification test.