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.