Abstract
Many plants accumulates proline dramatically under a variety of stress conditions, and this play an important role in regulation of osmotic homeostasis, prevention of damages caused by osmotic stresses, scavenging of reactive oxygen species and protection of cell structures. The regulation of proline accumulation in Saussurea amara seedlings and the activities of key enzymes involved in proline metabolism in response to salinity were studied, and 50-days-old seedlings were treated with NaCl(0, 100, 200, 300 and 400 mM) in this experiment. The results showed that proline contents were higher in leaves than in roots and increased significantly with NaCl concentration and treatment duration (P < 0.05). The activity of pyrroline-5-carboxylate synthetase (P5CS) increased at first and than decreased with increaso of NaCl concentration. The activities of orn-δ-aminotransferase (δ-OAT) and proline dehydrogenase (ProDH) increased and decreased, respectively, in response to elevated NaCl concentration and treatment duration. The data demonstrated that glutamate and ornthine pathway were activated by NaCl, and proline biosynthesis mainly depended on glutamate pathway under low-concentration NaCl condition, in which P5CS took dominant position. Conversely, the ornthine pathway was predominant. Key words: Saussurea amara seedlings, salinity stress, proline metabolism.
Highlights
Salinity is one of the major abiotic stresses affecting plant growth, development and productivity
Many plants accumulates proline dramatically under a variety of stress conditions, and this play an important role in regulation of osmotic homeostasis, prevention of damages caused by osmotic stresses, scavenging of reactive oxygen species and protection of cell structures
The regulation of proline accumulation in Saussurea amara seedlings and the activities of key enzymes involved in proline metabolism in response to salinity were studied, and 50-days-old seedlings were treated with NaCl (0, 100, 200, 300 and 400 mM) in this experiment
Summary
Salinity is one of the major abiotic stresses affecting plant growth, development and productivity. This constraint effects through osmotic inhibition, ionic toxicity and disturbance of the uptake and translocation of nutritional ions, disturb the physiological and biochemical functions of the plant cell and leads to cell death (Misra and Dwivedi, 2004; Xiong and Zhu, 2002). The glutamate pathway is catalyzed by a single bifunctional enzyme, pyrroline-5-carboxylate synthetase (P5CS) and produces gultamic-γ-semialdehyde (GSA), which is spontaneously converted to pyrroline-5-carboxylate (P5C) and reduced to proline (Nathalie and Christian, 2008; Maurizio et al, 2008; Silke et al, 2010).
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