Biology Reference
In-Depth Information
To determine the role of WRKY2 in seed germination and early seedling
growth, wild-type and wrky2 mutant seeds were germinated on MS medium
containing 0 µM, 0.5 µM, 1.0 µM, 1.5 µM, 2.0 µM ABA, and compared for
differences in germination and postgerminative growth. In the absence of ABA,
there was no significant difference in germination between wild-type and mutant
seeds (Figure 2 and Figure 3A). In the presence of ABA, both mutants germinated
later than wild type. On MS medium with 0.5 µM and 1.0 µM, 40% and 25%
of wild-type seeds germinated after one day, respectively. At these two concen-
trations, the germination rates of the two mutants were only about half of wild
type (Figure 2). On MS medium with 1.5 µM, 10% of wild-type seeds still ger-
minated, but no wrky2-1 and wrky2-2 seeds germinated. Likewise, significantly
more wild-type seeds germinated than the mutant seeds after two days on MS
medium with 1.5 µM and 2.0 µM ABA (Figure 2). Early seedling growth of both
mutants was also slower than that of wild type. After 7 d, 46% of wild-type but
only 4% of wrky2-1 and none of wrky2-2 mutants had green cotyledons on MS
medium with 1.5 µM ABA (Figure 4, 3B and 3C). These results show that wrky2
mutants are hypersensitive to ABA responses during germination and postgermi-
nation growth.
Figure 2.
ABA dose-response analysis of germination in wrky2-1 and wrky2-2 mutants.
Seeds were
germinated on MS plates containing 0
µ
M, 0.5
µ
M, 1.0
µ
M, 1.5
µ
M, and 2.0
µ
M ABA. Plates were
routinely kept for 3 days in the dark at 4°C and transferred to a tissue culture room under constant light at 22°C.
Germination efficiencies (radicle emergence) of wild type and wrky2 mutants seeds for 7 d after stratification.
Three independent experiments are shown, and above 100 seeds were used in each experiment.
