Occurrence and stress response of N-methylproline compounds in Tamarix species

A number of N-methylproline analogues have been found to accumulate in different species of Tamarix. These include N-methyl-l-proline (MP), trans-4-hydroxy-N-methyl-l-proline (M4HP) and trans-3-hydroxy-N-methyl-l-proline (M3HP). The three compounds appeared in all species but their relative and absolute levels depend upon species, ecotype and level of applied salt stress.