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Mešane okužbe rastlin z virusi so pogoste tako v naravi kot v gojenih rastlinah. Zanimal nas je odnos med pri nas razširjenim virusom Y krompirja (PVY) in virusom mozaika pepina (PepMV), ki se v zadnjem času hitro širi po Evropi, v Sloveniji pa še ni prisoten. Virusa imata podoben nabor gostiteljev in teoretično lahko okužita isto rastlino. Ker se vplivi mešanih okužb razlikujejo med gostitelji, smo izbrali 3 vrste testnih rastlin: krompir (Solanum tuberosum), paradižnik (Solanum lycopersicum) in vrsto tobaka Nicotiana benthamiana. Na različnih sortah krompirja smo rastline inokulirali na 3 različne načine (samo s PVY, samo s PepMV in z obema), da bi ugotovili, če izbrane sorte sploh lahko okužimo s PepMV. Pri paradižniku in tobaku smo vzpostavili 8 različnih načinov inokulacije, saj nas je zanimalo ali na uspešnost okužbe in bolezenska znamenja vpliva tudi časovni potek inokulacije. 4 tedne po mehanski inokulaciji smo popisali bolezenska znamenja, ki so se med vrstami razlikovala, in izolirali celokupno RNA iz izbranih vzorcev. Količino virusa v teh vzorcih smo določili s pomočjo kvantiativne verižne reakcije s polimerazo, pri čemer smo v raziskavo vključili tudi primerjavo normalizacij s pomočjo referenčnega gena COX in količino celokupne RNA ter ugotovili, da sta zelo primerljivi. Nobene od 6 sort krompirja nismo uspeli okužiti s PepMV. Paradižnik in tobak sta se okužila ne glede na to ali je bila inokulacija sočasna ali zaporedna. V nekaterih primerih smo pri mešanih okužbah zaznali mnogo močnejša bolezenska znamenja. Med nekaterimi načini inokulacije smo opazili razlike v količini virusov. Mixed infections of plant viruses are common in nature as well as in agriculturally important plants. We were interested in relationship between Potato virus Y (PVY) which is wide-spread in Slovenia and Pepino mosaic virus (PepMV) which is spreading fast across Europe. These two viruses have partially overlapping host ranges and can theoretically appear in the same plant. Effects of mixed infections differ in different hosts, thus we used 3 test hosts: potato (Solanum tuberosum), tomato (Solanum lycopersicum) and tobacco species Nicotiana benthamiana. On different varieties of potato, we established 3 treatments (only PVY, only PepMV and mixed infection) on tomato and tobacco we esatblished 8 inoculation treatments, to investigate if different time course of infection has an effect on relationship bewtween viruses in mixed infection and on the developed disease symptoms. 4 weeks after mechanical inoculation we checked disease symptoms, which differed between inoculation treatments, and isolated total RNA from plant samples. We determined virus titer in samples using quantitative polymerase chain reaction, and normalised the amount of viruses in two different ways: using reference gene COX and the amount of total RNA measured with fluorometry. We confirmed that the normalization methods are comparable. None of the potato varieties was infected with PepMV but in tomato and tobacco we observed mixed infection in case of coinfection and superinfection. In mixed infected plants we observed the strongest disease symptoms. There were differences in virus accumulation between some of the different inoculation treatments. |
