Increased transcriptional levels of genes encoding antioxidant enzymes play important protective roles in coping with excessive accumulation of reactive oxygen species (ROS) in plants exposed to various abiotic stresses. To fully elucidate different evolutions and functions of ROS-scavenging enzymatic genes, we isolated iron superoxide dismutase (
FeSOD), dehydroascorbate reductase (
DHAR) and monodehydroascorbate reductase (
MDHAR) from white clover for the first time and subsequently tested dynamic expression profiles of these genes together with previously identified other antioxidant enzyme genes including copper zinc superoxide dismutase (
Cu/ZnSOD), manganese superoxide dismutase (
MnSOD), glutathione reductase (
GR), peroxidase (
POD), catalase (
CAT), and ascorbate peroxidase (
APX) in response to cold, drought, salinity, cadmium stress and exogenous abscisic acid (ABA) or spermidine (Spd) treatment. The cloned fragments of
FeSOD,
DHAR and
MDHAR genes were 630, 471 and 669 bp nucleotide sequences encoding 210, 157 and 223 amino acids, respectively. Phylogenetic analysis indicated that both amino acid and nucleotide sequences of these three genes are highly conservative. In addition, the analysis of genes expression showed the transcription of
GR,
POD,
MDHAR,
DHAR and
Cu/ZnSOD were rapidly activated with relatively high abundance during cold stress. Differently,
CAT,
APX,
FeSOD,
Cu/ZnSOD and
MnSOD exhibited more abundant transcripts compared to others under drought stress. Under salt stress,
CAT was induced preferentially (3–12 h) compared to
GR which was induced later (12–72 h). Cadmium stress mainly up-regulated
Cu/ZnSOD,
DHAR and
MDHAR. Interestingly, most of genes expression induced by ABA or Spd happened prior to various abiotic stresses. The particular expression patterns and different response time of these genes indicated that white clover differentially activates genes encoding antioxidant enzymes to mitigate the damage of ROS during various environmental stresses.
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