title: OsACA6, a P-type IIB Ca²⁺ ATPase promotes salinity and drought stress tolerance in tobacco by ROS scavenging and enhancing the expression of stress-responsive genes.
abstract: Calcium (Ca²⁺) regulates several signalling pathways involved in growth, development and stress tolerance. Cellular Ca²⁺ homeostasis is achieved by the combined action of channels, pumps and antiporters, but direct evidence for a role of Ca²⁺ATPase pumps in stress tolerance is lacking. Here we report the characterization of a Ca²⁺ ATPase gene (OsACA6) from Oryza sativa, and elucidate its functions in stress tolerance. OsACA6 transcript levels are enhanced in response to salt, drought, abscisic acid and heat. In vivo localization identified plasma membranes as an integration site for the OsACA6-GFP fusion protein. Using transgenic tobacco lines, we demonstrate that over-expression of OsACA6 is triggered during salinity and drought stresses. The enhanced tolerance to these stresses was confirmed by changes in several physiological indices, including water loss rate, photosynthetic efficiency, cell membrane stability, germination, survival rate, malondialdehyde content, electrolyte leakage and increased proline accumulation. Furthermore, over-expressing lines also showed higher leaf chlorophyll and reduced accumulation of H₂O₂ and Na⁺ ions compared to the wild-type. Reduced accumulation of reactive oxygen species (ROS) was observed in transgenic lines. The increased proline accumulation and ROS scavenging enzyme activities in transgenic plants over-expressing OsACA6 efficiently modulate the ROS machinery and proline biosynthesis through an integrative mechanism. Transcriptional profiling of these plants revealed altered expression of genes encoding many transcription factors, stress- and disease-related proteins, as well as signalling components. These results suggest that Ca²⁺ ATPases have diverse roles as regulators of many stress signalling pathways, leading to plant growth, development and stress tolerance.
authors.affiliation: International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
authors.forename: Kazi M K
authors.initials: KM
authors.lastname: Huda
authors.forename: M Sufara Akhter
authors.initials: MS
authors.lastname: Banu
authors.forename: Bharti
authors.initials: B
authors.lastname: Garg
authors.forename: Suresh
authors.initials: S
authors.lastname: Tula
authors.forename: Renu
authors.initials: R
authors.lastname: Tuteja
authors.forename: Narendra
authors.initials: N
authors.lastname: Tuteja
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D018525:Germination; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000378:metabolism; D012275:Oryza / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D010788:Photosynthesis / Q000502:physiology; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D054712:Salinity; D013312:Stress, Physiological; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology
chemical_list: D010937:Plant Growth Regulators; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D000040:Abscisic Acid; D006861:Hydrogen Peroxide; D000252:Calcium-Transporting ATPases
keywords: Ca2+ATPases; Oryza sativa; abiotic stress; calcium signalling network; reactive oxygen species; stress tolerance