Importance of microRNA for seedling
development in Arabidopsis thaliana
Jennifer Coppersmith
Department of Biochemistry and
Biophysics
Mentor: Dr. Hiro Nonogaki (Horticulture)
Significance of Seed Development
Agriculture and Food
Why Arabidopsis?
pgrc3.agr.ca/images/seeds.gif
Arabidopsis Seed Structure
Testa
Endosperm
Embryo
Overview of Experiment
SPL13
T DNA insert
SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE13 (mSPL13)
microRNA
• 21-24nt in length
• Gene regulation at the mRNA level
www.qiagen.com/about/PressReleases/images/9.jpg
microRNA
mRNA
miRNA
miRNA
RISC
microRNA mutation
Mutation
mRNA
SPL13
GU G CU C UC U CU CU U CU G UC A
miR156
C ACG AG UG AG AG AAG AC AG U
miRNA
mSPL13 GU G CU
A CU U
A CU A
A
C UC U CU
G UC A
RISC
C ACG AG UG AG AG AAG AC AG U
Hypothesis: SPL13 needs to be down regulated by microRNA156 to maintain
normal developmental program for germination or seedling establishment.
Overaccumulation of SPL13
WT
SPL13
rRNA
Cont mSPL13
Mutant Phenotype
Cot
Cot
Cot
4 leaf seedling (normal)
Cot
2 leaf seedling (delayed)
Developmental Delay
4-leaf seedlings
2-leaf seedlings
Temporal Seedling Arrest
WT
mSPL13
CONTROL
Shoot Apical Meristem (SAM)
0d
2d
Storage Protein and Meristem
Hypocotyl
Radical
Meristem
Cot
Embryo
Meristem Development
3d
2
4
WT
mSPL13
1d
2d
WT
3d
4d
mSPL13
Visible Difference
WT
mSPL13
8d
Analysis
WT
mSPL13
SPL13
Based on phenotype, down
regulation of SPL13 via microRNA
is essential for proper meristem
development.
Determine Potential Targets of SPL13
miRNA156
SPL13
SPL13
Promoter
Gene X
X
Acknowledgements
Hiro Nonogaki
Kevin Ahern
Howard Hughes Medical Institute
Lab Members:
Masa Asahina
Tammy Chan
Po-Pu Liu
Jessica Kristof
Piotr Pupel
Jing Sun
SBP1
SBP2
SPL13
?
SQUAMOSA ( or APETALA1)
SQUA
AP1
- 455
- 429
TTCGACGTCCGTACAACAAGTCTTTAT
CCAGTGGTCCGTACAATGTTACTTACC
- 419
10 bp
conserved stretch
19-mer core seq
- 393
Normal Embryogenesis in mSPL13
Coppersmith JL, Hewitt JR, Nonogaki H, unpublished results