系统侵染的番茄植株中黄瓜花叶病毒的时序变化

Temporal change of Cucumber mosaic virus in systemic infected tomato seedlings

采用实时荧光定量PCR（FQ—PCR）和DAS—ELISA方法，研究了22—26℃温室条件下番茄幼苗中黄瓜花叶病毒CNA株系（CMV—CNA）各基因组RNA组分及其外壳蛋白（CP）含量的动态变化，同时结合同期感病植株症状发展和病情指数，分析并探讨CMV各基因组RNA、CP以及病症显示程度之间的时间效应及其相关性。以18SrRNA为内参照，FQ-PCR相对定量分析结果显示：接种后5—30d，CMV三分体基因组RNA在系统侵染的番茄组织中负荷量变化趋势大体一致，但是不同时期含量差异显著，均经历对数增长期、稳定期和回落期。其中，以RNA2负荷量变化情况最为平缓。DAS—ELISA检测结果显示：CP含量随接种时间延长而持续升高，但其对数增长趋势相对滞后于基因组RNA。番茄幼苗发病症状与CMV基因组RNA及CP负荷量的变化趋势大体一致，但症状表现时间相对滞后。CMV—CNA株系在番茄幼苗中以基因组RNA、CP以及病症显示先后次序出现高峰期，显示病毒基因组RNA及其CP在植物组织内负荷量的变化与植株症状表现并不同步。其动态变化规律将为研究CMV侵染机制，病毒与寄主互作及防病控病提供量化依据。

The loading dynamics of viral genomic RNA1, RNA2, RNA3 and coat protein （CP） of Cucumber mosaic virus CNA strain （CMV-CNA） in systemic tissue of infected tomato seedlings under 22 -26℃, as well as the symptom severity of host plants was investigated. Using 18S rRNA as endogenous control, the resuits of real-time fluorescent quantitative PCR （FQ-PCR） showed that the loading trends of all three RNA segments of CMV genome changed in five to thirty dpi （ days post inoculation） with obvious similarity and their loadings shown remarkable difference at different time of inoculation. The tested period could be divided into logarithmic increasing stage, stable stage and slowly decreasing stage. Compared with the other two RNA segments, the loading of RNA2 fluctuated much more gently. Furthermore, the results of DAS-ELISA indicated that the dynamic loading of CP paralleled to that of genomic RNA segments of CMV, but its logarithmic stage occurred a little later. Interestingly, the variation of symptom severity of inoculated tomato seedlings was similar to the loading of the three CMV segments, too, but started even later than that of the CP. Taken together, components of CMV-CNA accumulated differently at different time in systemically infected tomato seedlings. The loadings of CMV RNA segments and CP, and the symptom severity of tomato seedlings reached to their peaks asynchronously with the order of RNA segments, CP and symptom. The above results would contribute to the study of CMV infection mechanisms, the interactions of virus and plant hosts, and the viral diseases prevention.