Figure 1.
Effect of NaCl stress on proline accumulation of Jerusalem artichoke in roots (A), stems (B) and leaves (C).
30-day-old Jerusalem artichoke plantlets were treated with 0 or 100 mM NaCl (see Materials and Methods) for 12, 24, 48 and 72 h, respectively. All treatments had three biological replicates. Proline contents were measured by ninhydrin assay at A520 nm. Values represent means ± SE of three independent experiments. Significant differences (P≤0.05) between treatments are indicated by different letters.
Figure 2.
Effect of NaCl stress on P5CS activities of Jerusalem artichoke in roots (A), stems (B) and leaves (C).
30-day-old Jerusalem artichoke plantlets were treated with 0 or 100 mM NaCl (see Materials and Methods) for 12, 24, 48 and 72 h. All treatments had three biological replicates. P5CS activities were measured by hydroxylamine hydrochloride assay at A535 nm (see Materials and Methods). Values represent means ± SE of three independent experiments. Significant differences (P≤0.05) between treatments are indicated by different letters.
Figure 3.
Effect of NaCl stress on δ-OAT activities of Jerusalem artichoke in roots (A), stems (B) and leaves (C).
30-day-old Jerusalem artichoke plantlets were treated with 0 or 100 mM NaCl (see Materials and Methods) for 12, 24, 48 and 72 h. All treatments had three biological replicates. OAT activities were measured by ninhydrin method (see Materials and Methods). Values represent means ± SE of three independent experiments. Significant differences (P≤0.05) between treatments are indicated by different letters.
Figure 4.
Effect of NaCl stress on PDH activity of Jerusalem artichoke in roots (A), stems (B) and leaves (C).
30-day-old Jerusalem artichoke plantlets were treated with 0 or 100 mM NaCl (see Materials and Methods) for 12, 24, 48 and 72 h. All treatments had three biological replicates. OAT activities were measured by spectrophotometry at A340 at 25°C (see Materials and Methods). Values represent means ± SE of three independent experiments. Significant differences (P≤0.05) between treatments are indicated by different letters.
Figure 5.
Phylogenetic analysis of HtP5CS, HtOAT and HtPDH.
Protein sequences which had been reported were selected for sequence alignment. Sequence alignment analysis was performed using the ClustalW method in the Meglign program (DNASTAR, Inc., Madison, WI, USA). These genes’ accession numbers are : AtP5CS1 (NM_129539) and AtP5CS2 (NM_115419.4) in Arabidopsis; OsP5CS1 (D49714.1) and OsP5CS2 (NM_001051337) in rice (Oryza sativa); PvP5CS1 (EU340347), PvP5CS2 (EU407263) in common bean (Phaseolus vulgaris); SbP5CS1(GQ377719) and SbP5CS2(GQ377720) in sorghum (Sorghum bicolor); AtOAT (NM_123987.3) in Arabidopsis; BnOAT (EU375566.1) in rapeseed (Brassica Napus); GmOAT (NM_001250221.1) in soybean (Glycine max); MtOAT (AJ278819) in alfalfa (Medicago truncatula); NtOAT (ADM47437) in tobacco (Nicotiana tabacum);AtPDH1 (NM_113981.5) and AtPDH2 (NM_123232.2) in Arabidopsis; MsPDH (AY556386.1) in alfalfa (Medicago sativa); NtPDH1 (AY639145.1) and NtPDH2 (AY639146.1) in tobacco (Nicotiana tabacum).
Figure 6.
Expression profiles of HtP5CS1, HtP5CS2, HtOAT, HtPDH1, and HtPDH2 from roots, stems, and leaves under 100 mM NaCl stress in the time-course experiments.
30-day-old Jerusalem artichoke plantlets were treated with 0 or 100 mM NaCl (see Materials and Methods) for 1, 4 and 12 h individually. All treatments had three biological replicates. Total RNA was extracted from roots, stems and leaves for quantitative PCR (RT-qPCR) analysis. Transcript levels were first normalized to the level of a housekeeping gene actin (HtActin). The normalized transcript levels were then compared between treatment (100 mM NaCl) and control (0 mM NaCl) to calculate a fold change. Values represent means ± SE of three independent experiments. Significant differences (P≤0.05) between treatments are indicated by different letters.