Monitoring of virus and phytoplasma diseases by laboratory diagnostic methods (PCR, RT-PCR, DAS-ELISA) in apple and pear after sanitation process

Abstract: Sanitation of apple cultivar (‘Rubinstep’) and pear cultivars (‘Astra’, ‘Bohemica’, ‘David’, ‘Elektra’, ‘Erika’) was carried out by in vitro thermotherapy and chemotherapy. In the course of sanitation, the plant material was periodically tested to verify the suitability of selected methods. The presence of pathogens in selected initial trees was detected by PCR, RT-PCR and DAS-ELISA before the beginning of sanitation in 2005. Twenty clones of apple cultivar ‘Rubinstep’, 20 clones of pear cv. ‘Elektra’, 19 clones of pear cv. ‘Erika’, 20 clones of pear cv. ‘Astra’, 20 clones of pear cv. ‘Bohemica’, and 12 clones of pear cv. ‘David’ were tested after chemotherapy in years 2007-2008. Fifteen clones of pear cv. ‘Elektra’, 6 clones of cv. ‘Lada’ and 10 clones of cv. ‘Rubinstep’ were tested after thermotherapy in 2008. The occurrence of viruses Apple chlorotic leaf spot virus (ACLSV), Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV), Apple mosaic virus (ApMV) and phytoplasmas Candidatus ‘Phytoplasma pyri’ (CPP) and Candidatus ‘Phytoplasma mali’ (CPM) were monitored. The clones, which remained infected with viruses or phytoplasmas after therapy, were later discarded. Those in vitro clones that proved to be pathogen-free after repeated testing were further multiplied and in vitro rooted. The results presented here are preliminary.