title: Overexpression of bacterial mtlD gene in peanut improves drought tolerance through accumulation of mannitol.
abstract: In the changing global environmental scenarios, water scarcity and recurrent drought impose huge reductions to the peanut (Arachis hypogaea L.) crop yield. In plants, osmotic adjustments associated with efficient free radical scavenging ability during abiotic stress are important components of stress tolerance mechanisms. Mannitol, a compatible solute, is known to scavenge hydroxyl radicals generated during various abiotic stresses, thereby conferring tolerance to water-deficit stress in many plant species. However, peanut plant is not known to synthesize mannitol. Therefore, bacterial mtlD gene coding for mannitol 1-phosphate dehydrogenase under the control of constitutive promoter CaMV35S was introduced and overexpressed in the peanut cv. GG 20 using Agrobacterium tumefaciens-mediated transformation. A total of eight independent transgenic events were confirmed at molecular level by PCR, Southern blotting, and RT-PCR. Transgenic lines had increased amount of mannitol and exhibited enhanced tolerance in response to water-deficit stress. Improved performance of the mtlD transgenics was indicated by excised-leaf water loss assay and relative water content under water-deficit stress. Better performance of transgenics was due to the ability of the plants to synthesize mannitol. However, regulation of mtlD gene expression in transgenic plants remains to be elucidated.
authors.affiliation: Directorate of Groundnut Research, Post Box No. 5, Junagadh, Gujarat 362001, India.
authors.forename: Tengale Dipak
authors.initials: TD
authors.lastname: Bhauso
authors.affiliation: Directorate of Groundnut Research, Post Box No. 5, Junagadh, Gujarat 362001, India.
authors.forename: Thankappan
authors.initials: T
authors.lastname: Radhakrishnan
authors.affiliation: Directorate of Groundnut Research, Post Box No. 5, Junagadh, Gujarat 362001, India.
authors.forename: Abhay
authors.initials: A
authors.lastname: Kumar
authors.affiliation: Directorate of Groundnut Research, Post Box No. 5, Junagadh, Gujarat 362001, India.
authors.forename: Gyan Prakash
authors.initials: GP
authors.lastname: Mishra
authors.affiliation: Directorate of Groundnut Research, Post Box No. 5, Junagadh, Gujarat 362001, India.
authors.forename: Jentilal Ramjibhai
authors.initials: JR
authors.lastname: Dobaria
authors.affiliation: Directorate of Groundnut Research, Post Box No. 5, Junagadh, Gujarat 362001, India.
authors.forename: Kirankumar
authors.initials: K
authors.lastname: Patel
authors.affiliation: University of Delhi, Benito Juarez Road, New Delhi 110021, India.
authors.forename: Manchikatla Venkat
authors.initials: MV
authors.lastname: Rajam
mesh_terms: D010367:Arachis / Q000201:enzymology / Q000235:genetics*; D055864:Droughts; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000502:physiology*; D008353:Mannitol / Q000378:metabolism*; D035261:Plant Components, Aerial; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics; D030821:Plants, Genetically Modified / Q000235:genetics*; D013401:Sugar Alcohol Dehydrogenases / Q000096:biosynthesis / Q000235:genetics
chemical_list: D010940:Plant Proteins; D008353:Mannitol; D013401:Sugar Alcohol Dehydrogenases; C077257:mannitol-mannose 1-oxidoreductase