Indole-3-acetic acid-amido (IAA) synthetase that catalyzes the conjugation of amino acids to auxin specifically using the auxin precursor indole-3-butyric acid (IBA) and glutamine and, possibly, cysteine as substrates (PubMed:29462792, PubMed:30315112). Displays high catalytic activity with the auxinic phenoxyalkanoic acid herbicides 4-(2,4-dichlorophenoxy)butyric acid (2,4-DB) and to some extent 2,4-dichlorophenoxylacetic acid (2,4-D) as substrates, thus confering resistance to herbicides (PubMed:30315112). (indol-3-yl)butanoate + ATP + L-cysteine = (indol-3-yl)butanoyl-L-cysteine + AMP + diphosphate + H(+) (indol-3-yl)butanoate + ATP + L-glutamine = (indol-3-yl)butanoyl-L-glutamine + AMP + diphosphate + H(+) 4-(2,4-dichlorophenoxy)butanoate + ATP + L-glutamine = 4-(2,4-dichlorophenoxy)butanoyl-L-glutamine + AMP + diphosphate + H(+) kcat is 0.76 min(-1) with indole-3-acetic acid as substrate (in the presence of ATP and glutamine) (PubMed:29462792, PubMed:30315112). kcat is 10.2 min(-1) with indole-3-propionic acid as substrate (in the presence of ATP and glutamine) (PubMed:29462792). kcat is 9.9 min(-1) with indole-3-butyric acid as substrate (in the presence of ATP and glutamine) (PubMed:29462792, PubMed:30315112). kcat is 4.4 min(-1) with jasmonic acid as substrate (in the presence of ATP and glutamine) (PubMed:29462792). kcat is 17 min(-1) with glutamine as substrate (in the presence of ATP and indole-3-butyric acid) (PubMed:29462792). kcat is 4 min(-1) with glutamine as substrate (in the presence of ATP and jasmonic acid) (PubMed:29462792). kcat is 16 min(-1) with cysteine as substrate (in the presence of ATP and indole-3-butyric acid) (PubMed:29462792). kcat is 21 min(-1) with histidine as substrate (in the presence of ATP and indole-3-butyric acid) (PubMed:29462792). kcat is 13 min(-1) with methionine as substrate (in the presence of ATP and indole-3-butyric acid) (PubMed:29462792). kcat is 25 min(-1) with tyrosine as substrate (in the presence of ATP and indole-3-butyric acid) (PubMed:29462792). kcat is 13 min(-1) with ATP as substrate (in the presence of indole-3-butyric acid and glutamine) (PubMed:29462792). kcat is 11 min(-1) with 4-(2,4-dichlorophenoxy)butyric acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). kcat is 1.3 min(-1) with 2,4-dichlorophenoxylacetic acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). kcat is 52.3 min(-1) with glutamine as substrate (in the presence of ATP and 4-(2,4-dichlorophenoxy)butyric acid) (PubMed:30315112). kcat is 52.5 min(-1) with cysteine as substrate (in the presence of ATP and 4-(2,4-dichlorophenoxy)butyric acid) (PubMed:30315112). kcat is 43.1 min(-1) with histidine as substrate (in the presence of ATP and 4-(2,4-dichlorophenoxy)butyric acid) (PubMed:30315112). kcat is 27.5 min(-1) with methionine as substrate (in the presence of ATP and 4-(2,4-dichlorophenoxy)butyric acid) (PubMed:30315112). kcat is 12 min(-1) with tyrosine as substrate (in the presence of ATP and 4-(2,4-dichlorophenoxy)butyric acid) (PubMed:30315112). kcat is 4.3 min(-1) with 2,4,5-trichlorophenoxyacetic acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). kcat is 15.6 min(-1) with 4-(4-chloro-2-methylphenoxy)butanoic acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). kcat is 24 min(-1) with 4-(2-chlorophenoxy)butanoic acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). kcat is 5.4 min(-1) with 4-(2,6-dimethylphenoxy)butanoic acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). kcat is 29.8 min(-1) with 4-(4-methoxyphenoxy)butanoic acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). kcat is 16.2 min(-1) with 4-phenoxybutyric acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). kcat is 15 min(-1) with 4-phenylbutryic acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). kcat is 26.6 min(-1) with 5-phenylvaleric acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). kcat is 24 min(-1) with 5-(4-fluorophenyl)valeric acid as substrate (in the presence of ATP and glutamine) (PubMed:30315112). Expressed in seedlings, roots, and parts of the siliques. Expressed widely in young seedling, including roots, shoots, and cotyledons. In older seedlings, present the primary root, shoots, and cotyledons, but not in the root epidermal cells or root hairs. Later observed in the cotyledons and the shoots, but not in the true leaves. In adult plants, accumulates in the primary root and lateral root tips and in the roots near the root/shoot junction. In mature siliques, confined to the tip of the silique in the style just below the stigma and at the base of the silique in the replum and abscission zone of siliques. No visible phenotype in normal conditions (PubMed:29462792). Slight reduction in root length when grown on media containing indole-3-butyric acid (IBA) (PubMed:29462792). Hypersensitivity to the auxinic phenoxyalkanoic acid herbicide 4-(2,4-dichlorophenoxy)butyric acid (2,4-DB) (PubMed:30315112). Belongs to the IAA-amido conjugating enzyme family.