Agrobacterium tumefaciens enhances biosynthesis of two distinct auxins in crown galls ($) (Plant Cell Physiol.)

Kiyoshi et al. investigated auxin biosynthesis during the formation of crown galls by Agrobacterium tumefaciens. Agrobacterium introduces into the plant T-DNA containing two auxin biosynthesis genes iaaM (TRYPTOPHAN-2-MONOOXYGENASE) and iaaH (INDOLE-3-ACETAMIDE HYDROLASE). The authors used LC-MS/MS to show that the level of IAM (indole-3-acetamide), IAA (indole-3-acetic acid), PAM (phenylacetamide), PAA (phenylacetic acid) and related metabolites are increased in crown galls, suggesting that two distinct forms of auxin are produced. PAA shows weaker auxin activity is not transported via the the polar auxin transport system. The authors suggest that developing specific inhibitors of IaaM  could be an effective treatment for crown gall disease. (Summary by Arif Ashraf) Plant Cell Physiol. 10.1093/pcp/pcy182