Morphology And Specific Detection Of Some Populations Of Ditylenchus Destructor Occurring In China

Potato rot nematode, Ditylenchus destructor, is one the most important plant parasitic nematodes, which is listed as a quarantine pest in many countries of the world.Morphological and molecular comparisons and analysis were made among differnert geographic populations of D. destructor, and the methods for monoxenic cultrue and specific detection of D. destructor were established in this study.The monoxenic culture method of D. destructor on Botrytis cinerea was made by using Taian population. The effects of two temperatures, 20 ℃ and 25 ℃, on the reproduction of the nematode were compared, and a vast culture method of the nematode in the laboratory was constructed. The result indicated that the better condition for culturing D. destructor is at 25 ℃ in darkness.Morphological observation and morphometrics of three geographic D. destructor populations from Lanzhou, Weifang and Taian were studied. Combining both LM and SEM observation, some morphometrics differences among the Lanzhou population parasitizing the angelica , the Weifang and Taian populations parasitizing the sweet potato were detected, which are in the normal variation range of the intro-population of the species.Totally, the rDNA ITS regions of seven geographic populations of D. destructor were amplified and digested with 8 different restriction enzymes, MvaⅠ, Hin6Ⅰ, AvaⅠ, HaeⅢ, AluⅠ, HinfⅠ, RsaⅠ and Bsh1236Ⅰ, and sequences alignments were made among Lanzhou, Taian and Weifang populations. It was found that the fragment length of ITS region are different among the populatons, in which the sequence length of Lanzhou population is 915bp, Weifang population is 867 bp, and all the other five populations are 727 bp. ITS-RFLPs showed that the Lanzhou population and Weifang population yield different digestion patterns with the other five populations from sweat potato. Sequence alignments and analysis of the ITS regionsof rDNA indicated that there were insertion fragments in the ITS regions of the Lanzhou population and Weifang populations compared with other 5 populations, and the sequences similarity, excludeinsertion fragments, of the populations were more than 98%.According to the sequence character of the rDNA ITS region of D. destructor, a pair of specific primers were designed, and effectiveness were proved by specificly amplifying the corresponding ITS region of all the D. destructor populations. To test the sensitivity of the primers, one to five specimen of D. destructor were chosed for specific amplification. The result showed that all the D. destructor populations yielded a specific fragment with the length of 346bp. and the inter-genus species had no specific amplification. The target fragment was also amplified with the 1 to 5 specimen of D. destructor. It is indicated that the primers designed for specific detection of D. destructor was steady, specific and sensitive, and the procedure was fast.