Isolate Complex Infection Of Different Strains Of Potato Virus Y On Potato

Potato virus Y?PVY?is one of the most important plant viruses affecting potato production,and its strain differentiation is complex.Especially in the recent 10 years,with the increase in the incidence of PVY in potato growing regions,more recombinant strains have been found that the genomic structures are very similar but the pathogenicity is quite different.At the same time,in many potato growing regions,many PVY strains exist simultaneously,causing widespread concern.The purposes of this study were by using different PVY strains widely popular in Heilongjiang Province as materials to investigate whether PVY has cross-protection phenomenon on potato,to study the differences in the protective effect of treatment combinations among different strains and the effect of different inoculation interval on cross protection effect,and to examine the effect of cross protection on potato traits.Isolates of PVY^N-Wi-Wi and PVY^NTN-NW?SYR-II?strains,which are widely found in Heilongjiang potato-producing regions,were selected as the source materials and were artificially inoculated on two potato varieties,Favorita and Shepody.The inoculated plants were observed and tested using biological symptom,transmission electron microscopy,and quantitative real-time PCR?qPCR?to study the effects of experimental treatments on potatoes.The results are as follows:?1?Potato plants presented mild mosaic or no symptom when infected with PVY^N-Wi,but severe mosaic,leaf wrinkling and malformation happened when infected with PVY^NTN-NW?SYR-??.The similar symptoms to the ones as caused by PVY^NTN-NW?SYR-??were presence when infected with both PVY^N-Wi and the PVYN^TN-NW?SYR-II?at the same time.The plants showed only a lighter symptom when potato plants were proctetion-infected with PVY^N-Wi and after 15 days or more challenge-infected with PVY^NTN-NW?SYR-??.?2?The cells of plant infected with PVY^N-Wi were slightly deformed,but the cell structure of plant infected with PVY^NTN-NW?SYR-II?was much changed,and the chloroplast and other organelles were deformed seriously.When infected with PVY^N-Wi and PVY^NTN-NW?SYR-II?at the same time,the chloroplasts in the cells were seriously deformed,and secondary structures such as multiple vesicles were observed.However,protection infection of PVY^N-Wi was made and then after 15 days or more challenge infection of PVY^NTN-NW?SYR-II?was carried out,cell organelles changed little in cells.?3?Total virus content in plants infected at the same time with both PVY^N-Wi and PVY^NTN-NW?SYR-II?was higher than that of PVY^NTN-NW?SYR-II?and PVY^N-Wi infection alone.PVY^N-Wi and PVY^NTN-NW?SYR-II?had cross-protection.The expression of PVY^N-Wi-Wi were only detected,and that of PVY^NTN-NW?SYR-II?was not when PVY^N-Wi-Wi protection infection was made,and nine or more days later PVY^NTN-NW?SYR-II?challenge infection was done.?4?Varieties with different resistance had different responses to PVY infection.Shepody produced more serious biological symptoms than Favorita.Changes of cell structure and organelles were much more obvious,and the content of the virus in plants peaked earlier and was also higher in Shepody than in Favorita.?5?Different isolates of the same strain had different effects on potato.The HLJ-C-44isolate of the PVY^N-Wi produced symptoms slightly heavier than those produced by the HLJ-BDH-2 isolate.Potato cross protection against PVY infection exists.The results of this study are of great significance for the prevention and control of potato Y virus disease by cross protection and development of new PVY resistant varieties using biotechnology.