Recover from virus infection after a second challenge with PPV occurs already within the same growing cycle 
To further test the ability of the transgenic rootstocks to confer PPV-resistance in the wt scions, a group of apricot scions that were PPV-free in the previous cycle was challenged a second time with PPV and the presence of the virus evaluated twice within the same growing cycle (Table 2).
The first evaluation, using young leaves, was carried out eight weeks after chip-budding. RT-PCR analyses identified PPV in all plants. Notably, only five weeks later, thirteen weeks after re-infection, 44.4% to 55.6% of the wt plants, depending on the transgenic rootstock line, were virus-free (Table 2). The above data show that the PPV resistance conferred by the rootstocks was robust, already occurring within the same growing cycle and maintained in successive evaluation cycles.