Research On The Mechanism Of Ningnanmycin Prevent And Cure TMV

Tobacco mosaic virus (TMV) is a most serious disease in the wold, it is a systemic and infected RNA virus. Since the plants have no such an intact immunity and metabolizability system like animals, once infected, they would in states that affected by virus in their whole life. This has make it difficult to prevent and cure plant virus. It's a hard work to research the virus and to develop new antivirus medicaments, however, scientists of every countries have paid much attention to the researchs on controlling plant virus and also have acquired much achievements. After infected by TMV, the metabolism of tobacco is affected, some pathology changes occur such as the growth of plant slowing , the colour of tobacco leaves fading, the chlorophyll and protein content declining, the fluorescence spectrum of thylakoid membranes altering, the cell membrane changing and oxygen-evolving activity reducing. TMV has become one of the most serious disease in the agriculture production of our country, and experts have also done a lot of works in this field. Ningnanmycin is a new pollution-free bioticpesticide which is characterized by broad spectrum, high-efficiency, harmless and less-persistent, it has effect on virus disease of plant via inducing plant to bring PR protein systematically, reducing concentration of nucleocapsid in frond and destroying nucleocapsid structure. This paper has studied the chlorophyll content and total protein composition and the thylakoid membranes polypeptide composition of tobacco leaves which infected by TMV or treated with Ningnanmycin by means of SDS-PAGE and mild PAGE, and the thylakoid membranes protein changes were studied too by means of circular dichroism fluorescence spectrum in room temperature. Furthermore, we also determined the DCIP activity of the thylakoid membranes of tobacco leaves.The results indicate that the tobacco leaves appeared drapes when infected by TMV, and growth rate decreased. However, the samples treated with Ningnanmycin grew thriftily. The chlorophyll and carotenoid content declined in the samples infected by TMV, but they were in a good condition of the samples treated with Ningnanmycin. The SDS-PAGE results showed that the TMV coat protein appeared in both samples infected TMV and passivated. Compared with the samples treated with distilled water, the large subunit of Rubisco decreased and the small subunit increased in samples infected TMV, and the amount of PsaA, PsaB and 33KD protein content declined in tobacco leaves infected by TMV. These results indicate TMV infection affects the gene expression of the nucleus genome and chloroplast genome, thus affects both the carbon metabolism in photosynthesis and the protein compositions of PSI, PSII in thylakoid membranes. Ningnanmycin could passivated TMV during a very short time, but the passivation effect declined with increasing time, this implies that passivation do not react to the nucleocapsid directly, perhaps it's the pathogenesis-related (PR) proteins which work. The polypeptide in tobacco leaves treated with Ningnanmycin maintained well, and DCIP activity enhanced. However, the samples infected by TMV showed a reverse effect, DCIP activity fell, fluorescence emission intensity heightened, the status of Chla and Chlb in the thylakoid membranes changed. These results indicate that TMV infection influences both PSI and PSII. In the Ningnanmycin prevention experiment, we find out that 5 days samples grew well, and had higher chlorophyll content, there were no changes of polypeptide content and DCIP activity. Results of the Ningnanmycin cure TMV, the sooner the better. Ningnanmycin could passivate TMV in a short time, but the effect declined in a long time. All these results reveal that Ningnanmycin is a good bioticpesticide for restraining TMV.