Molecular characterization of ThIPK2, an inositol polyphosphate kinase gene homolog from Thellungiella halophila, and its heterologous expression to improve abiotic stress tolerance in Brassica napus

• Published in: Physiologia plantarum Vol. 136; no. 4; pp. 407 - 425
• Main Authors: Zhu, Jin-Qi, Zhang, Jian-Tao, Tang, Ren-Jie, Lv, Qun-Dan, Wang, Qiu-Qing, Yang, Lei, Zhang, Hong-Xia
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.08.2009; Blackwell Publishing Ltd; Blackwell
• Subjects: Amino Acid Sequence; Arabidopsis; Biological and medical sciences; Brassica napus; Brassica napus - enzymology; Brassica napus - genetics; Brassicaceae - enzymology; Brassicaceae - genetics; Dehydration - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Genes, Plant; Halophila; Hydrogen Peroxide - pharmacology; Molecular Sequence Data; Nicotiana tabacum; Oxidative Stress; Phosphotransferases (Alcohol Group Acceptor) - genetics; Phosphotransferases (Alcohol Group Acceptor) - metabolism; Plant physiology and development; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified - enzymology; Plants, Genetically Modified - genetics; Reverse Transcriptase Polymerase Chain Reaction; RNA, Plant - genetics; Salt-Tolerant Plants - enzymology; Salt-Tolerant Plants - genetics; Sequence Alignment; Sequence Analysis, DNA; Stress, Physiological; Thellungiella; Inositol; Enzyme; Abiotic stress; Transferases; Tolerance; Gene expression; Genetic transfer; Characterization; Molecular parameter; Gene; Plant physiology; Cruciferae; Dicotyledones; Angiospermae; Brassica napus; Spermatophyta; Polyphosphate kinase; Molecular domain; Heterologous; Oil plant (vegetal)
• ISSN: 0031-9317; 1399-3054
• DOI: 10.1111/j.1399-3054.2009.01235.x

Inositol polyphosphate kinases play important roles in diverse cellular processes. In this study, the function of an inositol polyphosphate kinase gene homolog named ThIPK2 from a dicotyledonous halophyte Thellungiella halophila was investigated. The deduced translation product (ThIPK2) shares 85% identity with the Arabidopsis inositol polyphosphate kinase AtIPK2β. Transient expression of ThIPK2-YFP fusion protein in tobacco (Nicotiana tabacum) protoplasts indicates that the protein is localized to the nucleus and plasma membrane, with a minor localization to the cytosol. Heterologous expression of ThIPK2 in ipk2Δ (also known as arg82Δ), a yeast mutant strain that lacks inositol polyphosphate multikinase (Ipk2) activity, rescued the mutant's salt-, osmotic- and temperature-sensitive growth defects. Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) revealed ubiquitous expression of ThIPK2 in various tissues, including roots, rosette leaves, cauline leaves, stem, flowers and siliques, and shoot ThIPK2 transcript was strongly induced by NaCl or mannitol in T. halophila as exhibited by real-time PCR analysis. Transgenic expression of ThIPK2 in Brassica napus led to significantly improved salt-, dehydration- and oxidative stress resistance. Furthermore, the transcripts of various stress responsive marker genes increased in ThIPK2 transgenic plants under salt stress condition. These results suggest that ThIPK2 is involved in plant stress responses, and for the first time demonstrate that ThIPK2 could be a useful candidate gene for improving drought and salt tolerance in important crop plants by genetic transformation.