Proline contents of six successional seral species.

<p>The proline contents were measured on July (7), August (8) and September (9) under three water deficient levels (severe, moderate and mild). Significant multi-comparison results of month were marked as a legend within a block (see associated ANOVAs results of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098872#pone-0098872-t001" target="_blank">Table 1</a>).</p

CAT activities of six successional seral species.

<p>The measurements were conducted on July (7), August (8) and September (9) under three water deficient levels (severe, moderate and mild). Significant multi-comparison results of month × species were marked on the first label row of the X-axes. And significant multi-comparison results of deficient level × species, deficient level × months and months were marked as legends within three blocks, respectively (see associated ANOVAs results of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098872#pone-0098872-t001" target="_blank">Table 1</a>). In the box of legend zone, species of <i>A. scoparia, S. viridis, A. sacrorum, A. giraldii, B. ischaemum</i> and <i>L. dahurica</i> were abbreviated as <i>Asc, Sv, Asa, Ag, Bi</i> and <i>Ld</i>, respectively.</p

SOD activities of six successional seral species.

<p>The measurements were conducted on July (7), August (8) and September (9) under three water deficient levels (severe, moderate and mild). Significant multi-comparison results of species and month × species were marked on the second and first label rows of the X-axes, respectively (see associated ANOVAs results of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098872#pone-0098872-t001" target="_blank">Table 1</a>).</p

MDA contents of six successional seral species.

<p>The MDA contents were measured on July (7), August (8) and September (9) under three water deficient levels (severe, moderate and mild). Significant multi-comparison results of month × species and species were marked on the first and second label rows of X-axes. Significant multi-comparison results of month and deficient level × species were marked as legends within two blocks (see associated ANOVAs results of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098872#pone-0098872-t001" target="_blank">Table 1</a>). In the box of legend zone, species of <i>A. scoparia, S. viridis, A. sacrorum, A. giraldii, B. ischaemum</i> and <i>L. dahurica</i> were abbreviated as <i>Asc, Sv, Asa, Ag, Bi</i> and <i>Ld</i>, respectively.</p

SOD activities of six successional seral species.

<p>The measurements were conducted on July (7), August (8) and September (9) under three water deficient levels (severe, moderate and mild). Significant multi-comparison results of species and month × species were marked on the second and first label rows of the X-axes, respectively (see associated ANOVAs results of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098872#pone-0098872-t001" target="_blank">Table 1</a>).</p

Responses of anti-oxidation, osmoregulation and membrane hurt of six successional seral species to three deficient levels measured on July, August and September.

<p>Anti-oxidation traits of the six species were measured as the activities of SOD, CAT and POD enzymes; osmoregulation and membrane hurt were measured as the contents of Pro and MDA, respectively. The table shows the results of the three-way univariate ANOVAs with the activities of SOD, CAT and POD, the contents of Pro and MDA as the dependent variables, and months, deficient levels and species as the independent variables. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098872#pone-0098872-g001" target="_blank">Figs. 1</a> to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098872#pone-0098872-g005" target="_blank">5</a> for means and standard errors. As the leaf samples were limited, some measurements of proline were missed, which lead to the degree freedom of total errors of proline were 83 (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098872#pone-0098872-g004" target="_blank">Fig. 4</a>). Other items were all 161.</p

Relative expression levels of <i>TrbSAMS</i> (A), <i>TrbSAMDC</i> (B), <i>TrbPAO</i> (C), and <i>TrbACS</i> (D) during different IBA-induced and untreated rooting phases in softwood cuttings of tetraploid black locust.

<p>Initiation phase (I). Callus induction phase (C). Root primordia formation phase (RP). Adventitious root formation and elongation phase (AR). Error bars represent the standard deviation (SD) calculated from three biological replicates with IBA, CK (n = 3). CK, control treatment; IBA, indole-3-butanoic acid.</p

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

Amino acid sequence alignment of TrbSAMS with SAMS sequences from other plant species.

<p>GenBank accession numbers for nucleotide sequences: <i>Glycine max</i>, XP_003550837.1; <i>Cajanus cajan</i>, AEY85025.1; <i>Glycine soja</i>, ABY25855.1; <i>Ricinus communis</i>, XP_002512570.1; <i>Medicago truncatula</i>, XP_003609861.1; <i>Vitis vinifera</i>, XP_002266358.1; <i>Populus trichocarpa</i>, XP_002312296.1; <i>Cucumis sativus</i>, XP_004168041.1; <i>Prunus persica</i>, AGF95108.1. The same and similar amino acid residues are highlighted in black and gray respectively; the underlined sequences indicate NADP-binding sites and substrate specificity domains. Three conserved motifs are indicated in red. Two SAM synthetase signature motifs are underlined.</p

Morphological changes in tetraploid black locust cuttings undergoing adventitious root development in a sand bed.

<p>a. Softwood cuttings before cutting. b. A white callus appeared at 10 days after cutting. c. A yellow callus appeared and tiny adventitious roots emerged (root primordium) at 15 days after cutting. d. Adventitious root formation and elongation at 20 days after cutting.</p