Poster: Hormone synthesis & metabolism
Abs #
474: Investigation of indole-3-butyric acid response mutants
The ubiquitous phytohormone auxin affects plant growth and development including responses in lateral root development, apical dominance, vascularization, phototropism, and gravitropism. Auxin is found in plants as indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA), which can be converted to IAA in a process similar to fatty acid β-oxidation. Arabidopsis IBA-response (ibr) mutants with defects in this conversion display enhanced root length and suppressed lateral root formation on exogenous IBA, but remain sensitive to IAA. Previously isolated ibr mutants are defective in fatty acid β-oxidation or peroxisomal matrix enzymes and arrest without supplemental sugar in the dark. We conducted a screen for IBA insensitivity in ~181,000 EMS-mutagenized seedlings and isolated 17 new ibr mutants. We classified these mutants according to different phenotypes on IBA or sugar and used recombination mapping to locate the defective genes. Eight were identified as new alleles of previously known mutants, including chy1, pxa1, ibr1, ibr3, acx1, and acx3. Future efforts will focus on identifying the genes defective in the other potentially novel ibr mutants, which may act directly in IBA β-oxidation or may possess different lesions that influence IBA transport, perception, or regulation. (This work was supported by the NSF and the Rice Undergraduate Scholars Program.)
