Evaluation of susceptibility of plum-trees to 'Candidatus Phytoplasma prunorum' using real-time PCR

One of the ways to control 'Candidatus Phytoplasma prunorum' infection is to find varieties of Prunus that are resistant or tolerant to the phytoplasma. Different real-time procedures have been recently described to quantify the number of phytoplasmas, thus, the main objective of this work was to evaluate some of these methods and apply them to estimate the concentration of the pathogen in field samples. The DNA extraction with PGB/CTAB and the amplification with two diverse real time protocols were the methods that reach amplifications at lower cycles and were the chosen methods to perform the study of susceptibility of 5 varieties of Prunus salicina and P.cerasifera. P.cerasifera presents the lowest percentage of infected trees. The higher percentage was obtained in the 'Pioneer' and 'Fortune' varieties despite not significant differences were obtained with the rest of varieties of P. salicina. The comparison of the estimated number of phytoplasmas did not reached statistical differences between the five varieties of Japanese plum due to the high intra-varietal variability detected.