Salicylic Acid Protects Nitrate Reductase Activity, Growth and Proline in Amaranth and Tomato Plants during Water Deficit

Abstract

Problem statement: Seedlings of Amaranthus hybridus cv. NHAC-3 (large green, amaranth) and Lycopersicum esculentum cv. Roma (tomato) were subjected to 7 days water stress at Early Vegetative (EV), Late Vegetative (LV), Early Flowering (EF) and Late Flowering (LF) stages of growth to study the impact on leaf water potential (ψ w ), Nitrate Reductase Activity (NRA), growth (plant height, shoot and root biomass) and proline content of both plants. Approach: Two concentrations of salicylic acid (1 and 3 mM SA) were applied to stressed plants to study the level of protection given by SA to the plants. Leaf ψ w was significantly reduced (p = 0.05) during stress treatment at nearly all stages of growth in both plants. Leaf ψ w was in the range -0.25 to -1.42 (unstressed) and -1.45 to -2.02 (stressed) in tomato plants while in amaranth it was -0.7 to -1.62 (unstressed) and -1.62 to -2.68 (stressed). As 3 mM SA increased leaf ψ w to values close to the control (unstressed plants). NRA was significantly (p = 0.05) reduced by stress treatment at the LV stage of amaranth, EF stage of tomato and LF stage of both plants. Results: Thus, the reduction of NRA was more pronounced at the reproductive stage of both plants. As 3 mM SA was effective in maintaining NRA at levels similar to the control in both plants. Stress treatment reduced plant height significantly (p = 0.05) at the vegetative stages of both plants and 3 mM was also effective in keeping plant height similar to the control. Though shoot biomass was affected by water stress, SA treatment was not very effective in preserving the biomass during stress. Root biomass of plants was reduced by stress treatment at the reproductive stage and only tomato plants responded positively to 3 mM SA. Proline content was only slightly increased at all stages of growth in stressed plants but 3 mM SA induced a two-fold increase in proline content at the vegetative stage of tomato (EV and LV) and significant increases (p = 0.05) at almost all stages of growth of amaranth. Conclusion/Recommendations: The build up of proline, an osmolyte, by SA in stressed plants increased the capacity of plants to absorb water from the soil as shown by the increase in leaf ψ w of both plants from -1.45 to -0.25 . SA was more effective in protecting the plants against the adverse effects of water stress when the stress was given at the vegetative stages (EV and LV) than at the flowering stages (EF and LF).

Sugarcane Response to Water-Deficit Stress during Early Growth on Organic and Sand Soils

“…Therefore, early detection of water-deficit stress is important for irrigation management and could serve as a selection mechanism for drought tolerance. Studies on other crops have indicated that leaf RWC and/or proline content are useful indicators for early detecting plant water-deficit stress (Bates et al, 1973;Aspinall and Paleg, 1981;Ilahi and Dorffling, 1982;Levy, 1983;Claussen, 2005;Gonzalez et al, 2008;Umebese et al, 2009;Paknejad et al, 2009). Ilahi and Dorffling (1982) investigated changes in proline of four maize varieties differing in drought resistance during a prolonged water stress period and found that proline levels increased continuously during the stress period in all the four varieties, but to different amounts with higher level of proline in the drought-susceptible varieties than the drought-resistant varieties.…”

Effects of Salt and Water Stress on Plant Growth and on Accumulation of Osmolytes and Antioxidant Compounds in Cherry Tomato

“…Proline is generally considered as a good indicator of environmental stress in tomato (Clausen, 2005) and there are many reports describing an increase in Pro contents as a response to water or salt stress in this species (Babu et al, 2012;Ghorbanli et al, 2013;Giannakoula and Ilias, 2013;Inal, 2002;Handa et al, 1986;Nahar and Gretzmacher, 2002;Umebese et al, 2009;Yokas et al, 2008), although it should be mentioned that data specific for cherry tomatoes are rather scarce (Maggio et al, 2007;Rosales et al, 2007). What is not so clear is the possible contribution of Pro accumulation to the (relative) resistance of tomato to salinity.…”

Fenugreek Seed Extract Enhanced the Growth of Vicia faba and Zea mays Seedlings

“…In a previous work, we found that wheat seedlings treated with coumarin exhibited a significant increase in phenolic, flavonoids and proline . Similarly, salicylic acid induced a two-fold increase in proline content at the vegetative stage of tomato plants (Umebese et al, 2009). In accordance with our results, chickpea and cucumber seedlings treated with ellagic and ferulic acids has markedly enhanced proline accumulation (Abu El-Soud et al, 2013 andLi et al, 2013) Cell damage occurs in consequent of adverse environmental stimuli which disrupts the normal homeostasis of affected cells.…”