Ameliorating Effects of Exogenously Applied Proline on Seed Composition, Seed Oil Quality and Oil Antioxidant Activity of Maize (Zea mays L.) under Drought Stress

Abstract

This study was carried out to appraise whether or not the exogenous application of a potential osmoprotectant, proline, could ameliorate the adverse effects of drought stress on maize seed and seed oil composition, as well as oil antioxidant activity. Water stress reduced the kernel sugar, oil, protein and moisture contents and most of the seed macro- and micro-elements analyzed in both maize cultivars but it increased the contents of seed fiber and ash. Water stress increased the oil oleic acid content with a subsequent decrease in the amount of linoleic acid, resulting in an increased oil oleic/linoleic ratio for both maize cultivars. However, no variation was observed in oil stearic and palmitic acids content due to water stress. A considerable drought induced an increase in seed oil α-, γ-, δ- and total tocopherols and flavonoids were observed in both maize cultivars. However, oil phenolic and carotenoid content as well as 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging activity decreased. Foliar-applied proline significantly increased the content of seed sugar, oil, protein, moisture, fiber and ash in both maize cultivars under well irrigated and water deficit conditions. Furthermore, exogenous application of proline increased the oil oleic and linoleic acid contents. The concentrations of antioxidant compounds namely phenolics, carotenoids, flavonoids and tocopherols estimated in the seed oil increased due to foliar-applied proline under water deficit conditions that was positively correlated with the enhanced oil DPPH free radical scavenging activity. Moreover, the increase in the contents of these antioxidant compounds and oil antioxidant activity due to the foliar application of proline was noted to be more pronounced under water deficit conditions.

Proline Accumulation in Leaves of Periploca sepium via Both Biosynthesis Up-Regulation and Transport during Recovery from Severe Drought

“…Secondary metabolites play important roles in plant adaptation to the changing environment and in overcoming stress conditions [48], [50]. Similar to the study on maize ( Zea mays L.) [51], exogenous Pro increased accumulation of secondary TF and TP under drought stress, confirming that Pro might also involve in activation of plant secondary metabolism [52]. When re-watered, plants with higher Pro concentration showed stronger antioxidant activity.…”

Application of proline to root medium is more effective for amelioration of photosynthetic damages as compared to foliar spraying or seed soaking in maize seedlings under short-term drought

“…Besides that, it can modulate the functions of mitochondria, influence plant growth, and induce the expression of some genes involved in abiotic stress tolerance (Szabados and Savaure, 2009). In addition to its major roles, PRO also plays an extremely important role in buffering cellular redox potential under abiotic stress conditions (Ali et al, 2013). PRO accumulation under various abiotic stress conditions is connected with stress tolerance in plants (Nanjo et al, 1999), and its concentration is generally higher in tolerant genotypes than in stress-sensitive ones (Ashraf and Foolad, 2007).…”

“…Therefore, PRO application to plants under abiotic stress is an important approach to mitigate the hazardous effects of the stress. Many reports have depicted that exogenous PRO could play an important role in increasing plant tolerance against abiotic stress factors (Ali et al, 2007(Ali et al, , 2013Ashraf and Foolad, 2007;Athar et al, 2008;Shahbaz et al, 2013). These reports included the responses of plants, especially under salt stress (Hoque et al, 2007;Shahbaz et al, 2013).…”

“…To the best of our knowledge, there are not enough records on ameliorating the effects of PRO application under drought stress. Furthermore, although PRO application improved the adverse effects of drought stress in plants (Ali et al, 2007(Ali et al, , 2013, its application was performed just as a foliar application (Ali et al, 2007(Ali et al, , 2013Moustakas et al, 2011) or in the rooting medium (Kamran et al, 2009) under drought stress in plants. The effectiveness of PRO applied via seed soaking mode to alleviate stress injuries is not well known.…”

Nitric Oxide Regulated Improvement in Growth and Yield of Rice Plants Grown Under Salinity Stress: Antioxidant Defense System

“…Among various groups of plant secondary metabolites, phenolics and AsA are important with both biological and antioxidant properties (Posmyk et al, 2009; Ali et al, 2013). The activity of phenolics as an antioxidant metabolite is due to its greater radical stabilization and proton donating ability (Rice- Evans et al, 1996).…”