Objective This study aims to shed light on the auxin biosyntheticpathway 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 B TRP an aminotransferase TAA1 that is used to CYP79B2/B3 TAR1 TAR2 convert TRP into IPA.M IAOx IPyA IAMM IAN IAM NIT SUR2 SUR1 YUC AMI UGT74B1 IGs IAA
Ethylene : Induce Auxin synthesis Col-O Ethylene Col wei8 wei8 tar2Air 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. Seedlings with the parental phenotype were selected for further analysis. 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.
Characterization of 2-93 at 3 days old Col wei8 wei8 tar2 2-93Standard mediaEthylene media Auxin media
Characterization of 2-93 at 10 days old Col wei8 wei8 tar2 2-93 AT10 days old AT DR5:GFP10 days old IAA10 days old IAA DR5:GFP10 days old
F2’s for 2-93 cross Cross Long root Total RatioCol 3 100 ~1:16Ler 4 105 ~1:16wei8 8 98 ~1:4 Results: *2-93 2-93 mutant cross to Col and to Ler presented a 1:16 ratio, 10% while the cross to wei8 presented 1:4 ratio meaning 5% *2-93 that it is a recessive mutation. 0% xCol x Ler x W8-1
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