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Nicole Colón CarriónDirection: Linda RoblesAlonso-Stepanova Lab
CHARACTERIZING AUXIN BIOSYNTHETIC MUTANTS IN ARABIDOPSIS THALIANA
Objective
This study aims to shed light on the auxin biosynthetic pathway by identifying genes involved in the pathway using a novel screen in Arabidopsis.
Auxin• Auxin biosynthesis can occur via tryptophan dependent or independent pathways• There are many unknowns in the auxin biosynthetic pathway and we hope to find regulating factors
● TAA1 gene encodes an aminotransferase that is used to convert TRP into IPA.
Ethylene : Induce Auxin synthesis
Ethylene
Col wei8
wei8 tar2
Col-O
Air Ethylene Figure 1. Represent the
effect of the lost of the aminotransferase
Enhancer screen for auxin biosynthetic mutants~50,000 wei8 DR5:GFP plants have been EMS mutagenized.
~100,000 plants have been screened.
~2100 “putants” have been picked.
Retesting of putants has been completed.
~ 200 have the loss of apical hook.
Of these, ~25 have a longer root.
Further characterization
Goal: To find other factors
contributing to auxin biosynthesis.
F2’s from crosses were analyzed at two timepoints for auxin sensitivity and ethylene
responses.
The recombination frequency was calculated.Recombination freq = total no of mutants/ total of offsprings X 100%
Root degeneration and DR5:GFP expression were monitored. Seedlings with the mutant phenotype were propagated for mapping.
Seedlings with the parental phenotype were selected for further analysis.
Mutants
18-40 Semi- dominant22-25-4 Recessive mutant21-44-5 Dominant12-20-2 Recessive mutant12-8-3 Recessive mutant2-93 Recessive mutant
Characterization of 2-93 at 3 days old
Ethylene media
Auxin media
Standard media
Col wei8 wei8 tar2 2-93
AT10 days
old
IAA10 days
old
ATDR5:GF
P10 days
old
IAADR5:GF
P10 days
old
2-93Col wei8
Characterization of 2-93 at 10 days oldwei8 tar2
F2’s for 2-93 cross
Cross Long root Total Ratio
Col 3 100 ~1:16
Ler 4 105 ~1:16
wei8 8 98 ~1:4
xCol x Ler x W8-1
0%2%4%6%8%
*2-93
*2-93
Results:2-93 mutant cross to Col and to Ler presented a 1:16 ratio, while the cross to wei8 presented 1:4 ratio meaning that it is a recessive mutation.
Chromosomal location of causal mutation in the 2-93 line
Acknowledgements• Dr. Alonso• Dr. Stepanova• Dr. Linda Robles• Dr. Sue Carson• Dr. Karen Merchante• Jeonga Yun• Dr. Nelson
Questions
THANKS FOR YOUR ATTENTION