Biology Reference
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times of that in the wild type. These observations show elevated expression of
WRKY2 by ABA treatment requires ABA2 and ABA3. These results strongly sug-
gest that ABI5, ABI3, ABA2 and ABA3 are important regulators of ABA-induced
WRKY2 expression.
The Response of WRKY2 to ABA Is Independent of miR159,
MYB33 and MYB101
It is known that ABA-induced miR159 accumulation requires ABI3 but is only
partially dependent on ABI5. Furthermore, MYB33 and MYB101, which are
miR159 targets, are positive regulators of ABA responses during germination and
are subject to ABA-dependent miR159 regulation [17]. Figure 8A indicates that
there was no significant difference in the level of mature miR159 between wrky2
mutants and the wild type. As shown in Figure 8B and Table 1, there was no dif-
ference in levels of transcripts of MYB33 and MYB101 either. These results indi-
cate that WRKY2-mediated ABA signaling pathway is independent of miR159
and its target genes (MYB33 and MYB101) during seed germination and post-
germination growth arrest.
Figure 8.
RNA levels of miR159, MYB33 and MYB101 in wrky2 mutants and wild type. RNA was extracted
from seedlings on MS medium without ABA or with 1.5
µ
M ABA 4 d or 7 d post-stratification.
(A) Each
lane contained 20
µ
g total RNA. Each experiment also was executed three times. (B) Relative RNA
levels of WRKY2 were analyzed using gene-specific primers by real-time PCR. Three independent experiments
are shown by reextracting RNA from other samples. Each experiment also was executed three times.
