Review Article

Amino Acids

, Volume 39, Issue 4, pp 933-947

First online:

Interdependence of threonine, methionine and isoleucine metabolism in plants: accumulation and transcriptional regulation under abiotic stress

  • Vijay JoshiAffiliated withBoyce Thompson Institute for Plant Research Email author 
  • , Je-Gun JoungAffiliated withBoyce Thompson Institute for Plant Research
  • , Zhangjun FeiAffiliated withBoyce Thompson Institute for Plant ResearchUnited States Department of Agriculture-Agricultural Research Service, Robert W. Holley Center for Agriculture and Health
  • , Georg JanderAffiliated withBoyce Thompson Institute for Plant Research

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Pathways regulating threonine, methionine and isoleucine metabolism are very efficiently interconnected in plants. As both threonine and methionine serve as substrates for isoleucine synthesis, their synthesis and catabolism under different developmental and environmental conditions also influence isoleucine availability. Together, methionine gamma-lyase and threonine deaminase maintain the isoleucine equilibrium in plants under varied substrate availabilities. Isoleucine and the two other branched-chain amino acids (BCAAs) (leucine and valine) share four common enzymes in their biosynthesis pathways and thus are coordinately regulated. Induction of free amino acids as osmolytes in response to abiotic stress is thought to play a role in plant stress tolerance. In particular, the accumulation of BCAAs is induced many-fold during osmotic stress. However, unlike in the case of proline, not much research has been focused on understanding the function of the response involving BCAAs. This review describes pathways influencing branched-chain amino acid metabolism and what is known about the biological significance of their accumulation under abiotic stress. A bioinformatics approach to understanding the transcriptional regulation of the genes involved in amino acid metabolism under abiotic stress is also presented.


Methionine Threonine Isoleucine Abiotic stress Regulation