title: Involvement of calcium and calmodulin in oxidative and temperature stress of Amaranthus lividus L. during early germination.
abstract: Both heat and chilling caused reduction in membrane protein thiol level and increased accumulation of thiobarbituric acid reactive substances in 72 hr old germinating tissues (indicators of oxidative stress) and reduced germination and early growth performances. Calcium chelator EGTA [Ethylene glycol-bis (2-aminoethylether)-N, N,N',N, tetra acetic acid] calcium channel blocker LaCI3 (Lanthanum chloride) and calmodulin inhibitor TFP (trifluroperazine) aggravated these effects of heat and chilling and added calcium reversed them. Imposition of heat and chilling stress during early germination also causes accumulation of reactive oxygen species (ROS) like 02(-) and H2O2. Calcium treatment significantly reduced the accumulation of both the toxic ROS, while EGTA, LaCl3 and TFP treatment enhanced the accumulation. Activities of antioxidative enzymes catalase (CAT), ascorbate peroxidase (APOX) and glutathione reductase (GR) and total thiol content decreased significantly under both heat and chilling stress in germinating Amaranthus seedlings. Seedlings raised with Ca2+ treatment under heat and chilling stress exhibit higher activities of CAT7 GR and APOX and total thiol level than the untreated plants. EGTA, LaCl3 and TFP treatment, on the other hand significantly reduce the activities of all anti-oxidative enzymes and total thiol level. The work clearly supports the view that Ca2+-signalling pathway plays significant role in limiting heat and chilling induced oxidative stress by upregulating antioxidative defense during recovery phase of post-germination event in Amaranthus lividus.
authors.affiliation: Post Graduate Department of Botany, Hooghly Mohsin College, Chinsurah-712 101, India.
authors.forename: Soumen
authors.initials: S
authors.lastname: Bhattacharjee
mesh_terms: D027721:Amaranthus / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D000975:Antioxidants / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology* / Q000502:physiology; D020013:Calcium Signaling; D002147:Calmodulin / Q000502:physiology*; D018525:Germination / Q000502:physiology*; D018384:Oxidative Stress; D010940:Plant Proteins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D013696:Temperature
chemical_list: D000975:Antioxidants; D002147:Calmodulin; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D002118:Calcium