COMPARISON OF VIRUS ERADICATION OF APPLE MOSAIC VIRUS FROM HOP BY ENCAPSULATION-DEHYDRATION CRYOTHERAPY AND MERISTEM CULTURE METHODS
Virus eradication of Apple mosaic virus (ApMV) from common hop (Humulus lupulus) was investigated by using either the encapsulation-dehydration cryopreservation protocol as a cryotherapy method or meristem culture protocol as a traditional virus eradication method. After seven days of cold pretreatment at 4°C, apical hop buds, sized either less than 0.5 or 0.5-1.0 mm, were isolated from ApMV positive in vitro cultures of a Finnish hop landrace accession. The buds for meristem culture virus eradication were put straight onto the basic regeneration medium. The rest of the buds were first encapsulated in alginate beads and pretreated on solid 0.75 M sucrose medium for three days. The capsules to be frozen were dehydrated for 4 h on silica gel in laminar air flow, followed by rapid freezing in cryotubes. The meristem culture treatment showed regrowth of 41%, whereas the cryotherapy treatment of unfrozen control samples showed regrowth of 4% and frozen samples regrowth of only 2%. ApMV was detected in 56 of the 62 tested hop samples, and only 6 hop samples gave a negative result in RT-PCR assay using ApMV specific primers. Four of the virus-free buds, sized either less than 0.5 or 0.5-1.0 mm, represented the meristem culture virus eradication method. Two of the virus-free cases were encapsulated and dehydrated buds of the size of less than 0.5 mm that had not been frozen. None of the negative samples represented the cryotherapy treated frozen samples. Thus, our results did not confirm the efficiency of the applied cryopreservation protocol as a cryotherapy method to eradicate ApMV from hop.
Nukari, A., Laamanen, J., Uosukainen, M. and Lemmetty, A. (2014). COMPARISON OF VIRUS ERADICATION OF APPLE MOSAIC VIRUS FROM HOP BY ENCAPSULATION-DEHYDRATION CRYOTHERAPY AND MERISTEM CULTURE METHODS. Acta Hortic. 1039, 113-119
Humulus lupulus, pathogen eradication, genetic resources, cryopreservation, plant virus