Molecular Cloning, Characterization and Expression Analysis of the <i>SAMS</i> Gene during Adventitious Root Development in IBA-Induced Tetraploid Black Locust
<div><p>S-Adenosylmethionine synthetase (SAMS) catalyzes the synthesis of S-adenosylmethionine (SAM), a precursor for ethylene and polyamine biosynthesis. Here, we report the isolation of the 1498 bp full-length cDNA sequence encoding tetraploid black locust (<i>Robinia pseudoacacia</i> L.) SAMS (<i>TrbSAMS</i>), which contains an open reading frame of 1179 bp encoding 392 amino acids. The amino acid sequence of TrbSAMS has more than 94% sequence identity to SAMSs from other plants, with a closer phylogenetic relationship to SAMSs from legumes than to SAMS from other plants. The TrbSAMS monomer consists of N-terminal, central, and C-terminal domains. Subcellular localization analysis revealed that the TrbSAMS protein localizes mainly to in the cell membrane and cytoplasm of onion epidermal cells and <i>Arabidopsis</i> mesophyll cell protoplasts. Indole-3-butyric acid (IBA)-treated cuttings showed higher levels of <i>TrbSAMS</i> transcript than untreated control cuttings during root primordium and adventitious root formation. <i>TrbSAMS</i> and its downstream genes showed differential expression in shoots, leaves, bark, and roots, with the highest expression observed in bark. IBA-treated cuttings also showed higher SAMS activity than control cuttings during root primordium and adventitious root formation. These results indicate that <i>TrbSAMS</i> might play an important role in the regulation of IBA-induced adventitious root development in tetraploid black locust cuttings.</p></div
