Skip to main content
ARS Home » Research » Publications at this Location » Publication #151653
Title: PARTIAL CHARACTERIZATION OF MAJOR IAA CONJUGATES IN ARABIDOPSIS

Author
item PARK, SEIJIN - UNIVERSITY OF MINNESOTA
item WALZ, ALEXANDER - TECHNISCHE UNIVERSITAT DR
item MOMONOKI, YOSHIE - TOKYO UNIV OF AGRICULTURE
item LUDWIG-MUELLER, JUTTA - TOKYO UNIV OF AGRICULTURE
item Slovin, Janet

Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/25/2004
Publication Date: 7/25/2004
Citation: Park, S., Walz, A., Momonoki, Y., Ludwig-Mueller, J., Slovin, J.P. 2004. Partial characterization of major iaa conjugates in arabidopsis. American Society of Plant Biologists Annual Meeting. Paper No. 669. Plant Biology 2003

Interpretive Summary:

Technical Abstract: Previous studies in Arabidopsis have found that total indole-3-acetic acid (IAA) levels determined by hydrolysis were much higher than the amount that could be accounted for by the free IAA and the conjugated forms known to be present. We found that peptide-like conjugates and protein-like conjugates accounted for 78% and 17%, respectively, of the total IAA pool. Free IAA and esterified conjugates constituted only <1% and 4%. Higher molecular weight esterified conjugates were not detected. Peptide-like conjugates increased during germination but smaller peptide-like conjugates declined. Based on solubility in solvent mixtures, the peptide-like conjugates appear to be relatively hydrophobic. To determine size, GPC was used and showed the molecular mass of each peptide component was less than 2000 Da. The peptide-like conjugates were further fractionated with C4 HPLC and analyzed by MALDI-TOF and ESI-TOF mass spectrometry. No molecules larger than 1900 Da were detected even after sample analysis conditions and MS acquisition parameters were varied. Each conjugate was also shown to contain IAA by GC-MS following 2N or 7N NaOH hydrolysis. These data suggest that peptide-like conjugates are major IAA conjugates in Arabidopsis. This contrasts with the only other plant where an IAA peptide and protein have been described in detail, Phaseolus vulgaris, where the peptide is a minor constituent and protein conjugates account for the bulk of the IAA. Consistent with this difference in the character of the IAA pool, transformation with a bean iap1-GFP gene construct did not result in iap1-IAA conjugation in Arabidopsis. Supported by NSF IBN0111530 and DFG.