Biology Reference
In-Depth Information
ortholog, OsWRKY71 act as a transcriptional repressor of gibberellin-responsive
genes in aleurone cells [42]. However, it is unclear whether WRKY genes medi-
ate ABA-dependent seed germination and postgermination growth arrest. In this
study, we report that wrky2-1 and wrky2-2 mutants are hypersensitive to ABA
during germination and postgermination early growth. We have analyzed genetic
interactions between the wrky2 mutant and the abi3-1 and abi5-1 mutants and
found that ABA hypersensitivity of the wrky2 mutants is attributable to increased
mRNA levels for ABI5, ABI3 and ABI5-induced Em1 and Em6. Furthermore,
ABI5, ABI3, ABA2 and ABA3 are important regulators of ABA-induced expres-
sion of WRKY2.
Results
WRKY2 T-DNA Insertion Mutants are Hypersensitive to ABA
During Seed Germination and Postgermination Early Growth
To analyze the molecular events in ABA-regulated germination and seedling
growth, we sought to identify WRKY transcription factors associated with these
growth and developmental stages. For this purpose, we screened T-DNA inser-
tion mutants for a number of Arabidopsis WRKY genes for altered sensitivity to
ABA based on their germination rates and seedling growth in MS media contain-
ing ABA. As shown in Figure 1, WRKY2 T-DNA insertion mutants wrky2-1
(Salk_020399) and wrky2-2 (Sail_739_F05) accumulated no WRKY2 transcript
of expected size and exhibited increased sensitivity to ABA during seed germina-
tion and seedling growth. The two mutants display no other obvious phenotypes
in morphology, growth, development or seed size (data not shown).
Figure 1.
Identification of wrky2 mutants by northern blot analysis.
RNA was
extracted from the seedlings that have grown on MS medium with 1.5
µ
M ABA 4 days after the end
of stratification. Each lane contained 20
µ
g total RNA. Each experiment also was executed three times.
