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Wenbin Wang,Xiangpo Qiu,Ho Soo Kim,Yanxin Yang,Dianyun Hou,Xuan Liang,곽상수 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.1
Dehydroascorbate reductase (DHAR) plays a critical role in the regeneration of ascorbic acid (AsA), and widely involved in plant tolerance to biotic and abiotic stresses. In this study, the IbDHAR3 gene was cloned from sweetpotato cultivar Xushu 18 by RT-PCR. The full-length of this gene was 813 bp which encodes 270 amino acids. The IbDHAR3 protein contained two conserved domains of glutathione S-transferase (GST) and GST-C-DHAR, and one chloroplast transit peptide with 52 amino acids length. Transient expression in tobacco leaf epidermal cells indicated that IbDHAR3 protein is subcellular localized to chloroplast. The qRT-PCR results revealed that the relative expression level of IbDHAR3 in leaves is much higher than that in other tissues, and could be up-regulated by ABA, drought, salinity, and high-temperature stresses. The seed germination rate and root elongation were increased in contrast to wild type under mannitol and NaCl stresses in T3 transgenic Arabidopsis overexpressing IbDHAR3 gene. The soil drought experiments showed that the overexpression of IbDHAR3 gene in Arabidopsis reduced the malondialdehyde (MDA) and the H2O2 content, enhanced the level of AtGR gene expression, superoxide dismutase (SOD), ascorbate peroxidase (APX), DHAR activity, and the AsA content. Therefore, overexpression of IbDHAR3 gene could enhance the ability of scavenging reactive oxygen species such as H2O2 by promoting AsA-glutathione cycle and related antioxidant enzymes system, thereby contributing to increased stress tolerance in Arabidopsis.
Wenbin Wang,Huan Yu,김호수,Yanxin Yang,Xiangpo Qiu,곽상수 한국식물생명공학회 2019 Plant biotechnology reports Vol.13 No.3
Trehalose-6-phosphate synthase (TPS) plays an important regulatory role in the response of plants to multiple abiotic stresses. However, our knowledge of the stress tolerance functions of TPS genes in sweet potato (Ipomoea batatas [L.] Lam) remains limited. In the present study, we isolated and functionally characterized the sweet potato gene encoding TPS1, IbTPS1. Sequence analysis showed that IbTPS1 belongs to class I TPS proteins and harbors highly conserved acceptor (glucose- 6-phosphate [Glc6P]) and donor (uridine diphosphoglucose [UDP-Glc]) binding sites. The IbTPS1 gene showed the highest level of constitutive expression in leaves and storage roots of sweet potato plants and was induced by several environmental stresses including drought, salt, and heat shock. The IbTPS1 protein might be localized to the cytosol. Complementation assay of yeast tps1Δ and tps1Δtps2Δ growth-defective mutants confirmed the TPS activity of IbTPS1, and truncation of the N-terminal extension of IbTPS1 (ΔNIbTPS1) increased the catalytic activity of the protein. Additionally, expression of IbTPS1 in yeast conferred abiotic stress tolerance to dehydration, salinity, and oxidation, and expression of ΔNIbTPS1 further enhanced the tolerance to abiotic stresses. The results of this study advance our understanding of the functions of IbTPS1 under abiotic stress conditions. Our results suggest that the IbTPS1 gene is an excellent candidate for improving the stress tolerance of different crop plants.