A Study of the Physiological, Biochemical and Molecular Regulations of Salt and Dehydration Tolerance Properties of Tomato
Plants are continuously faced with abiotic stresses, which limit their growth and production. An understanding of the mechanisms by which plants respond to such stresses can help in improving their tolerance levels, and their performance. The goal of this research was to investigate the biochemical and physiological properties leading to salt and dehydration stress tolerance in the tomato wild species Solanum chilense, compared with a susceptible cultivar, S. lycopercicon 'Walter'. For salt treatment, seedlings (3-7 days) were exposed to one-half strength Hoagland's solution (control), supplemented with 200 mM NaCl (treated) under uninterrupted aeration. For dehydration treatment, plants were removed from hydroponic medium for a period of 18 hrs until signs of wilting were evident, while plants serving as control remained in solution. Under salt stress, plant growth was reduced, along with mineral nutrient acquisition and chlorophyll content. Enzymatic analyses were conducted in root and leaf tissues to assess the activities of antioxidant enzymes. In roots, the activities of glutathione reductase (GR) and glutathione S-transferase (GST) were reduced under salt treatment, while the activities of catalase (CAT) and peroxidase (POX) increased. For dehydration treatment, GR and CAT activities increased while POX and GST had no change. In young and mature leaves, GR and GST activities were reduced under salt stress; however, under dehydration stress GR activity was high, while GST was slightly reduced. The activity of POX increased in young and mature leaves subjected to salt stress; however, negligible activity was seen in dehydrated leaves. Catalase activity was constant in young and mature leaves (neither increased nor decreased) subjected to salt stress while in dehydrated leaves, its activity was increased. Proteomic analysis was also conducted in roots of S. lycopercicon 'Walter' tomato cultivar and S. chilense subjected to dehydration stress. Over 12% of the proteins induced are associated with detoxification, namely GR, GST and POX. Our results suggest that plant's antioxidant system could play a role in salt and dehydration stress tolerance by protecting plants against ROS; while antioxidant proteins could serve as markers for tolerant traits.
"A Study of the Physiological, Biochemical and Molecular Regulations of Salt and Dehydration Tolerance Properties of Tomato"
ETD Collection for Tennessee State University.