Comparative characterization of sweetpotato antioxidant genes from expressed sequence tags of dehydration-treated fibrous roots under different abiotic stress conditions

Abstract

Drought stress is one of the most adverse conditions for plant growth and productivity. The plant antioxidant system is an important defense mechanism and includes antioxidant enzymes and low-molecular weight antioxidants. Understanding the biochemical and molecular responses to drought is essential for improving plant resistance to water-limited conditions. Previously, we isolated and characterized expressed sequence tags (ESTs) from a full-length enriched cDNA library prepared from fibrous roots of sweetpotato subjected to dehydration stress (Kim et al. in BMB Rep 42:271-276, [5]). In this study, we isolated and characterized 11 sweetpotato antioxidant genes from sweetpotato EST library under various abiotic stress conditions, which included six intracellular CuZn superoxide dismutases (CuZnSOD), ascorbate peroxidase, catalase, glutathione peroxidase (GPX), glutathione-S-transferase, thioredoxin (TRX), and five extracellular peroxidase genes. The expression of almost all the antioxidant genes induced under dehydration treatments occurred in leaves, with the exception of extracellular swPB6, whereas some antioxidant genes showed increased expression levels in the fibrous roots, such as intracellular GPX, TRX, extracellular swPA4, and swPB7 genes. During various abiotic stress treatments in leaves, such as exposure to NaCl, cold, and abscisic acid, several intracellular antioxidant genes were strongly expressed compared with the expression of extracellular antioxidant genes. These results indicated that some intracellular antioxidant genes, especially swAPX1 and CuZnSOD, might be specifically involved in important defense mechanisms against oxidative stress induced by various abiotic stresses including dehydration in sweetpotato plants.

On a Cold Night: Transcriptomics of Grapevine Flower Unveils Signal Transduction and Impacted Metabolism

“…Because of its specific role in the monolignol biosynthetic pathway, CAD expression is considered as a marker of lignin biosynthesis [145]. Under cold stress, it was already reported that CAD gene expression was induced in the sweet potato and Arabidopsis [2,146]. Moreover, it has been proposed that cell wall rigidity may be an important factor in cell resistance to freeze-induced dehydration [147].…”

Cell Wall Metabolism in Response to Abiotic Stress

“…Lignin biosynthesis genes are affected in the cold response. It was shown that CAD gene expression was induced in sweet potato or Arabidopsis in response to cold [ 161 , 172 ]. Other genes involved in lignin biosynthesis, including PAL , CCR , COMT (caffeate O -methyltransferase), and CCoAOMT , were shown to be up-regulated in pea and Phaseolus vulgaris in response to cold [ 161 , 164 , 173 , 174 ].…”

Effect of Drought on Storage Root Development and Gene Expression Profile of Sweetpotato under Greenhouse and Field Conditions

“…Evidence of the genetic basis of sweetpotato tolerance to drought comes from studies carried out in vitro along with field and greenhouse experiments (Ekanayake and Dodds, 1993;Ricardo, 2011). Genes associated with antioxidant activity were up-regulated in leaves under drought and salt stress (Kim et al, 2013). Similarly, transcripts of late embryogenesis abundant proteins, known to be associated with abiotic stress responses, were increased with lignification in sweetpotato tissue cultures (Park et al, 2011).…”