Molecular Identification And Sequence Analysis Of Potato Spindle Tuber Viroid From Heilongjiang

Potato samples, suspected Potato spindle tuber viroid (PSTVd), were collected fromHeilongjiang province which was the main producing area of potatoes. R-PAGE was conducted tofind the positive samples which were used for the subsequentidentification. The positive sampleswere identified using bioassay, RT-PCR and NASH and the like.Tomatoes were used as indicator plants for the bioassay, which was time-consuming but thesymptom was intuitive. Specific primers were designed to clone the whole genome sequence ofPSTVd, and the PCR product was purified and was linked with the vector. After Enzymeidentification and sequencing, the whole genome sequence length was357bp.The sequence wasaligned with the severe strains, mild strains and intermediate strains. The results showed that thesimilarity,above95%, is very high and no base changed in center conserved region (180-220bp).Moreover, one of the samples, closer to the severe strains in North America, was determined assevere strain of PSTVdpreliminarilybased on the result of bioassay. However, most of the sampleswere identified as mild strains according to the results of sequence alignment and bioassay. Withthe enhancement of domestic and foreign trade, the increasingly frequent exchange of plantgermplasm resources, some parts of samples infected with PSTVd have shown the symptoms ofsever strains. Even so,the majority of PSTVd strains, infecting potatoes, are mild strains currently.The infection of PSTVd is usually accompanied by the incidence of Potato leafrollvirus(PLRV). Although the correlation is not necessary, there may be synergistic infectionmechanism between them to some extent. Our research have made some experiments preliminary,whilethe specific mechanism of coordination infection needs further study.This study aims to establish and improve the potato viroid detection system, andinvestigatethe recent occurrence, distribution, infection types of PSTVd in Heilongjiangprovince,which can provide effective scientific reference for the potato production, introduction andexchange of germplasm.