title: A Medicago truncatula EF-hand family gene, MtCaMP1, is involved in drought and salt stress tolerance.
abstract: BACKGROUND
  Calcium-binding proteins that contain EF-hand motifs have been reported to play important roles in transduction of signals associated with biotic and abiotic stresses. To functionally characterize genes of EF-hand family in response to abiotic stress, an MtCaMP1 gene belonging to EF-hand family from legume model plant Medicago truncatula was isolated and its function in response to drought and salt stress was investigated by expressing MtCaMP1 in Arabidopsis.
  
  
  RESULTS
  Transgenic Arabidopsis seedlings expressing MtCaMP1 exhibited higher survival rate than wild-type seedlings under drought and salt stress, suggesting that expression of MtCaMP1 confers tolerance of Arabidopsis to drought and salt stress. The transgenic plants accumulated greater amounts of Pro due to up-regulation of P5CS1 and down-regulation of ProDH than wild-type plants under drought stress. There was a less accumulation of Na(+) in the transgenic plants than in WT plants due to reduced up-regulation of AtHKT1 and enhanced regulation of AtNHX1 in the transgenic plants compared to WT plants under salt stress. There was a reduced accumulation of H2O2 and malondialdehyde in the transgenic plants than in WT plants under both drought and salt stress.
  
  
  CONCLUSIONS
  The expression of MtCaMP1 in Arabidopsis enhanced tolerance of the transgenic plants to drought and salt stress by effective osmo-regulation due to greater accumulation of Pro and by minimizing toxic Na(+) accumulation, respectively. The enhanced accumulation of Pro and reduced accumulation of Na(+) under drought and salt stress would protect plants from water default and Na(+) toxicity, and alleviate the associated oxidative stress. These findings demonstrate that MtCaMP1 encodes a stress-responsive EF-hand protein that plays a regulatory role in response of plants to drought and salt stress.
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, The Chinese Academy of Sciences, Beijing, PR China. whzhang@ibcas.ac.cn
authors.forename: Tian-Zuo
authors.initials: TZ
authors.lastname: Wang
authors.forename: Jin-Li
authors.initials: JL
authors.lastname: Zhang
authors.forename: Qiu-Ying
authors.initials: QY
authors.lastname: Tian
authors.forename: Min-Gui
authors.initials: MG
authors.lastname: Zhao
authors.forename: Wen-Hao
authors.initials: WH
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D055864:Droughts; D020832:EF Hand Motifs; D006861:Hydrogen Peroxide / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D046913:Medicago truncatula / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011392:Proline / Q000378:metabolism; D012492:Salts / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D012492:Salts; D008315:Malondialdehyde; D011392:Proline; D012964:Sodium; D006861:Hydrogen Peroxide