Exogenously Applied Ascorbic Acid-Mediated Changes in Osmoprotection and Oxidative Defense System Enhanced Water Stress Tolerance in Different Cultivars of Safflower (Carthamus tinctorious L.).

Ayesha Farooq,Mohammed Nasser Alyemeni,Parvaiz Ahmad,Shazia Anwer Bukhari,Leonard Wijaya,Nudrat A Akram,Muhammad Ashraf

doi:10.3390/plants9010104

Abstract

The present study was conducted to examine the effect of exogenously applied ascorbic acid (AsA) on osmoprotectants and the oxidative defense system in four cultivars (16171, 16183, 16207 and 16246) of safflower under well-watered and water deficit conditions. Water stress (60% field capacity) significantly decreased the shoot and root fresh and dry weights, shoot and root lengths and chlorophyll contents in all four safflower cultivars, while it increased the leaf free proline, total phenolics, total soluble proteins, hydrogen peroxide content and activities of catalase, superoxide dismutase and peroxidase enzymes. Foliar-applied (100 mg L−1 and 150 mg L−1) ascorbic acid caused a marked improvement in shoot and root fresh and dry weights, plant height, chlorophyll and AsA contents as well as the activity of peroxidase (POD) enzyme particularly under water deficit conditions. It also increased the accumulation of leaf proline, total phenolics, total soluble proteins and glycine betaine (GB) content in all four cultivars. Exogenously applied AsA lowered the contents of MDA and H2O2, and the activities of CAT and SOD enzymes. Overall, exogenously applied AsA had a positive effect on the growth of safflower plants under water deficit conditions which could be related to AsA-induced enhanced osmoprotection and regulation of antioxidant defense system.

Highlights

Drought stress can negatively affect the yield of various foods and crops, by influencing their physio-biochemical features [1,2]
Water stress (60% field capacity) significantly (p ≤ 0.001) decreased the shoot and root fresh and dry weights of all four (16171, 16183, 16207 and 16246) cultivars of safflower (Table 1; Figure 1A–D)
Foliar-applied (100 and 150 mg L−1 ) ascorbic acid (AsA) significantly improved shoot and root biomass of safflower cultivars under water deficit conditions except for cultivar 16207 wherein the biomass remained unchanged

Summary

Introduction

Drought stress can negatively affect the yield of various foods and crops, by influencing their physio-biochemical features [1,2]. Enhanced food demand for the growing population and water shortage due to lower rainfall and other climatic changes may cause famine [3]. Drought stress can directly affect photosynthesis, development, nutrient uptake/accumulation and osmotic adjustment, causing a marked suppression in crop yield [1,4,5]. Water deficit interferes with photosynthesis either by altering the photosynthetic metabolic pathway or by inducing the over-generation of oxidative stress. Decline in the rate of photosynthesis is affected by reduced CO2 diffusion [6]. Photosynthetic pigments and thylakoid membranes are denatured by water deficit conditions [7]. Hydrogen peroxide, superoxide, peroxide and hydroxyl radicals are Plants 2020, 9, 104; doi:10.3390/plants9010104 www.mdpi.com/journal/plants

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Conclusion