3.3. Southern blot analysis
Results showed that all tested transformants had one or more
hybridization bands, whereas the wild type did not show a band
(Table 1 and Fig. 2). This suggested that plasmid pBluescript II
KS-hph had successfully inserted into T23 as also confirmed by
PCR results. Among all tested transformants, seven transformants
were observed with a single copy blotting band while three transformants
were found with multiple copy blotting bands (Fig. 2,
lane E, J and K). If the plasmid integration was due to a REMI event,
a single 4.0 kb band was expected. Among the transformants with
a single blotting band, five mutants showed an integration event
has happened probably at the same single chromosomal site and
two of them showed an insertion bigger than the size of the
plasmid. Additionally, two hybridization bands were observed in
the remaining three transformants. These results, thus, indicated
that it was possible that the restriction sites, for the endonuclease
(HindIII was used in REMI), were not regenerated at both ends
during integration or the pBluescript II KS-hph plasmid might be
integrated into two different genomic loci.
3.4. Assessment of tolerance to imidacloprid
All transformants derived from T. atroviride T23 were measured
for their tolerance to imidacloprid based on their colony diameters
on a given imidacloprid concentration containing PDA medium. A
total of 153 transformants were found with better growth than
the parent T23 in the 200 lgmL1 imidacloprid containing growth
medium.