Molecular characterization of tocopherol biosynthetic genes in sweetpotato that respond to stress and activate the tocopherol production in tobacco

• Published in: Plant physiology and biochemistry Vol. 106; pp. 118 - 128
• Main Authors: Ji, Chang Yoon, Kim, Yun-Hee, Kim, Ho Soo, Ke, Qingbo, Kim, Gun-Woo, Park, Sung-Chul, Lee, Haeng-Soon, Jeong, Jae Cheol, Kwak, Sang-Soo
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.09.2016
• Subjects: Antioxidants; Biosynthetic Pathways - drug effects; Biosynthetic Pathways - genetics; Droughts; Gene Expression Regulation, Developmental - drug effects; Gene Expression Regulation, Plant - drug effects; Genes, Plant; Ipomoea batatas - drug effects; Ipomoea batatas - genetics; Ipomoea batatas - microbiology; Ipomoea batatas - physiology; Nicotiana - drug effects; Nicotiana - genetics; Nicotiana - microbiology; Organ Specificity - drug effects; Organ Specificity - genetics; Oxidative stress; Oxidative Stress - drug effects; Oxidative Stress - genetics; Pathogen infection; Plant Leaves - drug effects; Plant Leaves - genetics; Plant Leaves - growth & development; Plant Leaves - metabolism; Plants, Genetically Modified; Sequence Analysis, DNA; Sodium Chloride - pharmacology; Stress, Physiological - drug effects; Stress, Physiological - genetics; Subcellular Fractions - metabolism; Sweetpotato; Tocopherol; Tocopherols - metabolism; Transient expression; Oxidative stress; HGA; HPP; HPT; Transient expression; TC; Antioxidants; Sweetpotato; DMPBQ; Pathogen infection; ROS; TMT; Tocopherol; HPPD; MPBQ MT
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2016.04.037

Tocopherol (vitamin E) is a chloroplast lipid that is presumed to be involved in the plant response to oxidative stress. In this study, we isolated and characterized five tocopherol biosynthetic genes from sweetpotato (Ipomoea batatas [L.] Lam) plants, including genes encoding 4-hydroxyphenylpyruvate dioxygenase (IbHPPD), homogentisate phytyltransferase (IbHPT), 2-methyl-6-phytylbenzoquinol methyltransferase (IbMPBQ MT), tocopherol cyclase (IbTC) and γ-tocopherol methyltransferase (IbTMT). Fluorescence microscope analysis indicated that four proteins localized into the chloroplast, whereas IbHPPD observed in the nuclear. Quantitative RT-PCR analysis revealed that the expression patterns of the five tocopherol biosynthetic genes varied in different plant tissues and under different stress conditions. All five genes were highly expressed in leaf tissues, whereas IbHPPD and IbHPT were highly expressed in the thick roots. The expression patterns of these five genes significantly differed in response to PEG, NaCl and H2O2-mediated oxidative stress. IbHPPD was strongly induced following PEG and H2O2 treatment and IbHPT was strongly induced following PEG treatment, whereas IbMPBQ MT and IbTC were highly expressed following NaCl treatment. Upon infection of the bacterial pathogen Pectobacterium chrysanthemi, the expression of IbHPPD increased sharply in sweetpotato leaves, whereas the expression of the other genes was reduced or unchanged. Additionally, transient expression of the five tocopherol biosynthetic genes in tobacco (Nicotiana bentamiana) leaves resulted in increased transcript levels of the transgenes expressions and tocopherol production. Therefore, our results suggested that the five tocopherol biosynthetic genes of sweetpotato play roles in the stress defense response as transcriptional regulators of the tocopherol production. •Five tocopherol biosynthetic genes were isolated and characterized from sweetpotato.•Five tocopherol biosynthetic genes increased their expressions and tocopherol production in tobacco.•This is the first report on five tocopherol biosynthetic genes in sweetpotato.