ThePseudomonas savastanoitryptophan-2-mono-oxygenase is biologically active inNicotiana tabacum

摘要

It has been proposed that the “eukaryotic” T-DNA-encoded indole-3-acetic acid (IAA) biosynthesis genes ofAgrobacterium tumefaciensand their prokaryotic counterpart inPseudomonas savastanoioriginated from common ancestor genes. This paper provides additional evidence for the functional similarity between the gene products. We have demonstrated that a chimeric gene consisting of the coding sequence of theP. savastanoitryptophan-2-mono-oxygenase (iaaMgene) and a plant promoter encodes an active enzyme inNicotiana tabacum. Transformants obtained with this chimeric gene grew as a callus on hormone-free media. No stably transformed plantlets could be isolated. The callus tissues contained extremely high levels of indole-3-acetamide and slightly elevated levels of IAA. Either indole-3-acetamide by itself has a low auxin activity or, alternatively, it is converted aspecifically and at low rates into IAA. TheP. savastanoitryptophan-2-mono-oxygenase activity in plants is also able to detoxify the amino-acid analogue 5-methyltryptophan. This property can be used for positive selection of transformed ca