Abstract
Betaine biosynthesis pathway of plants involves S-adenosylmethionine synthetase (SAMS) and choline monooxygenase (CMO). SAMS is also involved in the other biosynthesis pathways such as that of lignin. We cloned putative SAMS and CMO genes of Atriplex nummularia and named them AnSAMS and AnCMO, respectively. The transcript levels of AnSAMS were increased by salt stress in leaves and stems. The transcript levels of AnCMO were higher in leaves and stems than in roots, and up-regulated by salt stress. The transcript regulation pattern of AnSAMS highly resembled that of AnCMO in the leaves during and after relief from salt stress. In the leaves, betaine and lignin are relatively abundant, and the betaine content was increased but the lignin content was not changed by salt stress. These results suggest that the transcript level of AnSAMS is controlled to supply SAM for betaine synthesis in the leaves.
