Overcoming phytoplasma infection in Paulownia tomentosa by meristem in vitro culture

Paulownia witches’ broom (PaWB) is caused by phytoplasma of Aster Yellows group, and resulted in severe damage to the growth and premature death of the infected tree.  In vitro cultures of meristems are important tools for solving problems with plant diseases. In recent study meristem cultures from phytoplasma infected Paulownia tomentosa have been created in an attempt to obtain healthy plants. The faster procedure with longer explants generated 95% regeneration but no healthy plants. The combination of smaller explants and thermotherapy resulted in the generation of plantlets with a healthy phenotype. The PCR analyzes showed the absence of phytoplasma only in one of the produced plants. Despite the low efficiency, expressed in one phytoplasma-free regenerant of a total of 480 explants, these results can serve to continue the work on optimizing the used strategy.