Molecular characterization of genes encoding isoamylase-type debranching enzyme in tuberous root of sweet potato, Ipomoea batatas (L.) Lam.

Moe Nabemoto, Riho Watanabe, Mizuho Ohsu, Kaname Sato, Motoyasu Otani, Osamu Nakayachi, Masao Watanabe

    Research output: Contribution to journalArticle

    Abstract

    Isoamylase (ISA) is a starch debranching enzyme that removes α-1,6-glucosidic linkages in α-polyglucans such as amylopectin. From previous studies, plant isoamylases have been shown to play a crucial role in amylopectin biosynthesis; however, little is known about their function in storage root tissues of plants such as cassava, yam and sweet potato. In this study, we isolated cDNA clones and characterized the cDNA nucleotide sequences of three genes (IbISA1, IbISA2, IbISA3) encoding isoamylase from sweet potato (Ipomoea batatas (L.) cv. White Star). Deduced amino acid sequences of the three isolated IbISAs have the specific regions that are highly conserved among the α-amylase family members. The product of IbISA2 is predicted to be enzymatically inactive, like other plant ISA2s, due to replacement of amino acid residues that are important for hydrolytic reaction. qRT-PCR analysis demonstrated that expression of IbISA2 was higher than that of the other two IbISAs (IbISA1 and IbISA3) in tuberous root at 109 days after planting, at which stage of tuberous root was at which stage tuberous roots were almost fully developed almost developed. This expression pattern observed in our experiments was different from that in other sink organs, such as seeds (endosperms), indicating that orchestration of ISA gene expression may depend on the differences in sink organ type between tuberous roots and seeds. The molecular characterization of three IbISA genes and their expression analysis in this study will contribute to further studies on starch biosynthesis in sweet potato, especially in storage root.

    Original languageEnglish
    Pages (from-to)351-359
    Number of pages9
    JournalPlant Biotechnology
    Volume33
    Issue number5
    DOIs
    Publication statusPublished - 2016 Jan 1

    Keywords

    • Genes encoding isoamylase-type starch debranching enzymes
    • Ipomoea batatas (L.)
    • Tuberous root

    ASJC Scopus subject areas

    • Biotechnology
    • Agronomy and Crop Science
    • Plant Science

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