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Plant Cell. 2015 Apr;27(4):1265-78. doi: 10.1105/tpc.15.00058. Epub 2015 Apr 21.

The Tyrosine Aminomutase TAM1 Is Required for β-Tyrosine Biosynthesis in Rice.

Author information

1
Boyce Thompson Institute for Plant Research, Ithaca, New York 14853.
2
Graduate School of Agriculture, Kyoto University, Kyoto 808-8502, Japan.
3
Section of Plant Breeding and Genetics, School of Integrated Plant Sciences, Cornell University, Ithaca, New York 14853.
4
Boyce Thompson Institute for Plant Research, Ithaca, New York 14853 gj32@cornell.edu.

Abstract

Non-protein amino acids, often isomers of the standard 20 protein amino acids, have defense-related functions in many plant species. A targeted search for jasmonate-induced metabolites in cultivated rice (Oryza sativa) identified (R)-β-tyrosine, an isomer of the common amino acid (S)-α-tyrosine in the seeds, leaves, roots, and root exudates of the Nipponbare cultivar. Assays with 119 diverse cultivars showed a distinct presence/absence polymorphism, with β-tyrosine being most prevalent in temperate japonica cultivars. Genetic mapping identified a candidate gene on chromosome 12, which was confirmed to encode a tyrosine aminomutase (TAM1) by transient expression in Nicotiana benthamiana and in vitro enzyme assays. A point mutation in TAM1 eliminated β-tyrosine production in Nipponbare. Rice cultivars that do not produce β-tyrosine have a chromosome 12 deletion that encompasses TAM1. Although β-tyrosine accumulation was induced by the plant defense signaling molecule jasmonic acid, bioassays with hemipteran and lepidopteran herbivores showed no negative effects at physiologically relevant β-tyrosine concentrations. In contrast, root growth of Arabidopsis thaliana and other tested dicot plants was inhibited by concentrations as low as 1 μM. As β-tyrosine is exuded into hydroponic medium at higher concentrations, it may contribute to the allelopathic potential of rice.

PMID:
25901084
PMCID:
PMC4558700
DOI:
10.1105/tpc.15.00058
[Indexed for MEDLINE]
Free PMC Article

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