Specialized 16SrX phytoplasmas induce diverse morphological and physiological changes in their respective fruit crops
Fig 5
Analysis of translocation in phloem sieve elements of uninfected and phytoplasma infected apple, pear and peach trees.
The translocation was examined with the determination of the velocity of the phloem mass flow (cm h-1) using fluorescence and with the calculation of volumetric flow rates (cm3 h-1) in mean single sieve elements. Both parameters were individually determined for (A) apple, (B) pear and (C) peach trees. Apple trees were infected with ‘Candidatus Phytoplasma mali’ inducing apple proliferation (AP). Pear trees were infected with ‘Candidatus Phytoplasma pyri’ causing pear decline (PD) and peach trees were infected with ‘Candidatus Phytoplasma prunorum’ inducing European stone fruit yellows (ESFY). Infected apple trees (AP) showed a significant decrease of phloem mass flow velocity and volumetric flow rates in contrast to infected pear trees (PD) where a significant rise was observed. In infected peach trees (ESFY) the phloem mass flow velocity was not affected but the volumetric flow rate decreased significantly. Box-whisker plots with median as lines and jittered raw values as closed circles (corresponding to each measurement). Boxes represent the interquartile range (IQR) and whiskers extend to 1.5*IQR. Bars represent the 95% confidence intervals with the estimated marginal means obtained from mixed effect models as dots (both back transformed to the response scale). Letters indicate statistical differences between EMMs of groups at the 0.05 significance level.