title: Differentially expressed myo-inositol monophosphatase gene (CaIMP) in chickpea (Cicer arietinum L.) encodes a lithium-sensitive phosphatase enzyme with broad substrate specificity and improves seed germination and seedling growth under abiotic stresses.
abstract: myo-Inositol monophosphatase (IMP) is an essential enzyme in the myo-inositol metabolic pathway where it primarily dephosphorylates myo-inositol 1-phosphate to maintain the cellular inositol pool which is important for many metabolic and signalling pathways in plants. The stress-induced increased accumulation of inositol has been reported in a few plants including chickpea; however, the role and regulation of IMP is not well defined in response to stress. In this work, it has been shown that IMP activity is distributed in all organs in chickpea and was noticeably enhanced during environmental stresses. Subsequently, using degenerate oligonucleotides and RACE strategy, a full-length IMP cDNA (CaIMP) was cloned and sequenced. Biochemical study revealed that CaIMP encodes a lithium-sensitive phosphatase enzyme with broad substrate specificity, although maximum activity was observed with the myo-inositol 1-phosphate and l-galactose 1-phosphate substrates. Transcript analysis revealed that CaIMP is differentially expressed and regulated in different organs, stresses and phytohormones. Complementation analysis in Arabidopsis further confirmed the role of CaIMP in l-galactose 1-phosphate and myo-inositol 1-phosphate hydrolysis and its participation in myo-inositol and ascorbate biosynthesis. Moreover, Arabidopsis transgenic plants over-expressing CaIMP exhibited improved tolerance to stress during seed germination and seedling growth, while the VTC4/IMP loss-of-function mutants exhibited sensitivity to stress. Collectively, CaIMP links various metabolic pathways and plays an important role in improving seed germination and seedling growth, particularly under stressful environments.
authors.affiliation: National Institute of Plant Genome Research (NIPGR), Aruna Asaf Ali Marg, New Delhi 110067, India.
authors.forename: Saurabh C
authors.initials: SC
authors.lastname: Saxena
authors.forename: Prafull
authors.initials: P
authors.lastname: Salvi
authors.forename: Harmeet
authors.initials: H
authors.lastname: Kaur
authors.forename: Pooja
authors.initials: P
authors.lastname: Verma
authors.forename: Bhanu Prakash
authors.initials: BP
authors.lastname: Petla
authors.forename: Venkateswara
authors.initials: V
authors.lastname: Rao
authors.forename: Nitin
authors.initials: N
authors.lastname: Kamble
authors.forename: Manoj
authors.initials: M
authors.lastname: Majee
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D001205:Ascorbic Acid / Q000378:metabolism; D029863:Cicer / Q000201:enzymology / Q000235:genetics*; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000235:genetics; D006861:Hydrogen Peroxide / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism; D008094:Lithium / Q000494:pharmacology; D008315:Malondialdehyde / Q000378:metabolism; D008969:Molecular Sequence Data; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics; D036226:Seedlings / Q000254:growth & development*; D013312:Stress, Physiological; D013379:Substrate Specificity
chemical_list: D007295:Inositol Phosphates; D010940:Plant Proteins; C002647:inositol 1-phosphate; D008315:Malondialdehyde; D008094:Lithium; D006861:Hydrogen Peroxide; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase; D001205:Ascorbic Acid
keywords: Ascorbate; gluconeogenesis; inositol; multifunctional; phosphatase; seed germination; stress tolerance.