Etiologic Analysis Of Processing Tomato Top-yellowing Disease And Identification Of Potato Virus M In Xinjiang

The virus diseases of processing tomato were widely investigated from fifteen main processing tomato producing areas in Xinjiang province, including Shihezi, Manasi, Hutubi, Jimusaer and Heshuo during 2009 to 2010. The field symptom of top-yellowing was found in tomatoes besides mosaic and fernbrake leaf ect. The top-yellowing of processing tomato are different from common yellowing, tomato plants affected by the yellowing developed total yellow on the upper leaves, but the middle and lower leaves seems normal. The yellow plants appeared random distribution pattern in the field with an infect frequencies of 2%-50%. There are some differences in incidence and disease severity, significant relation was not found in variety, cultivation patterns and irrigation modes.Microwave digestion and ICP-AES were used to detect the contents of nine elements in top leaves from infected and normal plants. The result showed that the contents of B, K, Mo, Na, Zn in infected plants were significantly higher than in normal plants. Obvious differences was not exist between the infected and normal plants in the contents of Fe, Ca. And the disease was not resulted from physiological element deficiencies. Different size of virus particles were observed by electron microscopy on virus preparation from processing tomato top- yellowing leaves. The PAS-ELISA detection of 30 processing tomato samples with top- yellowing disease showed that the detection rate of CMV, ToMV, TMV, BBWV were 100%,96.7%,66.7%,70.0% respectively. When each special primer was designed based on the CP gene sequences of TMV, ToMV, CMV, PVS, PVM and the exactly fragments were amplified by RT-PCR, the results were correspond to the detection of ELISA. It is preliminarily considered that the top-yellowing of processing tomato could be associated with those viruses, the exact etiology of it is not clear at present.The RT-PCR products of the PVM-R/F primer was cloned and sequenced. The cloned segment was compared and analysised with other genomic sequence of PVM from GENEBANK. It demonstrated that the cloned segment was one piece of PVM gene and consists of 1198 nucletides,contains complete CP gene(it was called PVM-XJ). The identity of nucleotides were 74.0%-95.8% with the isolates from China(AJ437481), American(AF023877), Poland(AY311394), Iran (EF397743), Latvia(GQ496609), Russia(NC001361), Germany(X57440) andItaly(X85114), Canada(EF063383,EF063384,EF063387). PVM-XJ has the closest genetic relationship with the isolate from Russia, and it has the farthest genetic relationship with the isolate from Canada (EF063387). PVM was detected in tomatoes by molecular detection methods at the first time in Xinjing.