AtGenExpress: Effect of auxin inhibitors on seedlings

1
AtGenExpress Effect of auxin inhibitors on
seedlings

• Experimenters Hideki Goda , Shigeo Yoshida ,
  Tadao Asami , Yukihisa Shimada
• Institute AtGenExpress
• Presentation Daniel Lunn

2
AtgeneExpress??
Project??

• To create an atlas of Arabidopsis gene
  expression.

Goal??

• To establish a full expression pattern for all
  genes in Arabidopsis

3
Auxin

• Auxin is not a single molecule it is a family of
  hormones in plants.

• Most commonly known for root, shoot initiation.

• In root/shoot development they compete with
  cytokinins. When auxins are expressed in the
  highest concentration roots development. When
  cytokinins are in the highest concentration
  shoots develop.

4
The experiment

• 7 day old seedlings treated for 3 hours with four
  different auxin inhibitors

• 2,4,6-T (2,4,6-trihydroxybenzamide)
• PCIB (p-chlorophenoxyisobutyric acid),
• TIBA (2,3,5-triiodobenzoic acid),
• NPA (naphthylpthalamic acid).

• All treatments were 10uM.
• All results obtained were significant to Pgt0.05

5
Mock compared to 2,4,6-T

• Gene At1g17170 was most up regulated, with a
  12.79 fold increase
• Gene At1g26250 was most down regulated.

6
Conclusions from Mock compared with 2,4,6-T

• At1g17170 encodes a gluthathion transferase,
  which is involved in shoot development.

• At1g26250 encodes a structural constituent of the
  cell wall

7
Mock compared to NPA

• Gene At2g23170 was the most up regulated by 8.685
  fold
• Gene At1g26320 was the most down regulated.

8
Conclusions from Mock compared with NPA

• At2g23170 encodes a protein which responds to
  auxin stimulus.

• Redundancy???

• At1g26320 encodes a zinc binding protein involved
  in oxidative response

9
Mock compared to PCIB

• Gene At1g17170 was most up regulated with a 5.328
  fold increase

• Gene At1g25150 was the most down regulated.

10
Conclusions from Mock compared with PCIB

• Once again gene At1g17170 encodes glutathion
  transferase.

• Gene At2g25150 is expressed in the cotyledon.

• Establishes the auxin/cytokinin gradient?

11
Mock compared to TIBA

• Gene At1g05680 was the highest up regulated with
  a 127.3 fold increase.
• Gene At1g34510 was the most down regulated gene.

12
Conclusions from Mock compared with TIBA

• Gene At1g05680 is currently unknown however it
  has been shown to be linked with oxidation stress
  response.

• Gene At1g34510 is known to be involved in the
  oxidative response. This gene and At1g26320 are
  both down regulated in the absence of auxin.

• Therefore two conclusions can be drawn
• One auxin must have a role in oxidative response.
• Possibly At1g05680 is a redundant gene, which
  acts in absence of auxin.

13
Final Slide (Promise)

• Hopefully my presentation should have
• Shown that we are only on the tip of
  understanding biological pathways.
• There are many unknowns.
• A simple knockdown, (e.g. inhibition of auxin)
  may not silence a gene product.
• However bioinformatics gives us an excellent
  starting point, to identify possible genes in a
  pathway, and will be a vital tool in the future.

14
Thankyou for you time!

• References
• www.arabidopsis.org
• www.arabidopsis.info
• www.ensembl.org/index.html