Biology Reference
In-Depth Information
WRKY2 Mediates Signal Pathway of ABA-
Dependent Germination and Postgermination
Early Growth
During germination, ABA can activate de novo late embryogenesis programs to
confer osmotic tolerance in arrested, germinated embryos [15]. During a short
development window, ABI3, ABI5 and late embryogenesis genes are reactivated
by ABA. ABI3 acts upstream of ABI5 and is essential for ABI5 gene expression.
ABA induces ABI5 occupancy on the promoter of Em1 and Em6, and activates
these late embryogenesis-abundant genes [15,16]. To analyze the expression of
these genes in wrky2 mutants, we germinated the wild type and wrky2 mutants
on MS medium with 0 and 1.5
µ
M ABA for 4 or 7 days. Total RNA was isolated
and analyzed using quantitative RT-PCR with gene-specific primers. As shown in
Figure 6, when these seedlings have grown on MS medium without ABA 4 days
post-stratification, expression of ABI5, ABI3, Em1 and Em6 was reduced in the
wrky2 mutants relative to that in the wild type. At 7 days post-stratification, wild
type and wrky2 mutants accumulated similar levels of transcripts for ABI3, ABI5,
Em1 and Em6 (Figure 6).
Figure 6.
RNA levels of ABI5, ABI3, Em1 and Em6 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 after the end
of stratification. Relative RNA levels of 4 genes 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.
