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.
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 AtIPK2beta. 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 ipk2Delta (also known as arg82Delta), 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.
Zhu
Jin-Qi
JQ
National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
Zhang
Jian-Tao
JT
Tang
Ren-Jie
RJ
Lv
Qun-Dan
QD
Wang
Qiu-Qing
QQ
Yang
Lei
L
Zhang
Hong-Xia
HX
D000595:Amino Acid Sequence; D029688:Brassica napus / Q000201:enzymology* / Q000235:genetics; D019607:Brassicaceae / Q000201:enzymology / Q000235:genetics*; D003681:Dehydration / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055051:Salt-Tolerant Plants / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013312:Stress, Physiological
D010940:Plant Proteins; D018749:RNA, Plant; D006861:Hydrogen Peroxide; D017853:Phosphotransferases (Alcohol Group Acceptor); C434257:inositol polyphosphate multikinase