Polyamine Acclimation Alleviates Hypersalinity-Induced Oxidative Stress in a Marine Green Macroalga, Ulva Fasciata, by Modulation of Antioxidative Enzyme Gene Expression1

Abstract

Transcripts and enzyme activities of antioxidative enzymes were increased by hypersalinity (90‰) in a marine macroalga, Ulva fasciata Delile (Lu et al. 2006, Sung et al. 2009). This study examined the effects of polyamines (PAs) on the induction of hypersalinity tolerance through the modulation of expression of antioxidative defense enzymes. Incubation of U. fasciata grown under 30‰ in the presence of putrescine (Put), spermidine (Spd), or spermine (Spm) (1 mM) for 12 h increased internal PA contents prior to 90‰ treatment. Spd or Spm pretreatments reduced H O accumulation and lipid peroxidation during 90‰ treatment and improved the recovery growth rate after transfer from 90‰ to 30‰. Increases in iron superoxide dismutase (FeSOD; EC 1.15.1.1) activity and transcript levels observed under 90‰ were further increased by Spd and Spm pretreatments, while Put pretreatment had no effect. Increases in MnSOD activity and transcript levels observed under 90‰ were enhanced by Spd and Put pretreatment. An observed increase in catalase (CAT; EC 1.11.1.6) activity and transcript levels under 90‰ was not affected by Spd and Spm pretreatments but was inhibited by Put pretreatment. Observed increases in ascorbate peroxidase (APX; EC 1.11.1.11) activity and transcript levels under 90‰ were inhibited by Put, Spd, and Spm pretreatments. In conclusion, Spd and Spm treatment affords U. fasciata protection against hypersalinity through the up-regulation of FeSOD gene expression, thereby alleviating oxidative damage.

Polyamine effects on protein disulfide isomerase expression and implications for hypersalinity stress in the marine algaUlva lactucaLinnaeus1

“…), and several genes related to stress defenses and protein synthesis (ribosomal protein) and destination are markedly up‐regulated by hypersalinity stress (Sung et al. , ,b).…”

“…Hyposalinity exposure induced the accumulation of free Put, Spd, and Spm (Lee , Lee and Chen ), whereas hypersalinity led to a decrease in free Put, Spd, and Spm contents (Sung et al. ). The evidence suggests that Put accumulation is one of the causal factors for hyposaline injury in U .…”

“…lactuca tolerance to hypersalinity stress can be significantly induced by Spd or Spm pretreatment, but Put pretreatment could not induce hypersalinity tolerance (Sung et al. ). Increasing the antioxidant defense capacity is at least one of the mechanisms for Spd or Spm‐mediated U .…”

“…lactuca acclimation to hypersalinity stress (Sung et al. ). Based on the changes in mRNA expression levels and enzyme activities, Spd or Spm pretreatment provides U .…”

“…lactuca with protection against hypersalinity stress through the up‐regulation of FeSOD gene expression, thereby alleviating oxidative damage (Sung et al. ).…”