Seed Pretreatment and Foliar Application of Proline Regulate Morphological, Physio-Biochemical Processes and Activity of Antioxidant Enzymes in Plants of Two Cultivars of Quinoa (Chenopodium quinoa Willd.)

Abstract

In the current study, the effects of exogenously applied proline (25 and 50 mM) and low-temperature treatment were examined on the physiochemical parameters in the plants of two cultivars (V1 and V2) of quinoa (Chenopodium quinoa Willd.). The seeds were also exposed to chilling stress at 4 °C before sowing. Plants raised from the seeds treated with low temperature showed reduced plant growth and contents of chlorophyll and carotenoids, but they had significantly increased contents of malondialdehyde, proline, ascorbic acid, total free amino acids, total soluble sugars, and total phenolics, as well as the activity of the peroxidase (POD) enzyme. Cold stress applied to seeds remained almost ineffective in terms of bringing about changes in plant root, hydrogen peroxide, glycine betaine and activities of superoxide dismutase (SOD), and catalase (CAT) enzymes. The exogenous application of proline significantly increased plant growth, the contents of chlorophyll, carotenoids, proline, ascorbic acid, total free amino acids, phenolics, and total soluble sugars, as well as the activities of SOD, POD, and CAT, but it decreased malondialdehyde content. Overall, foliar application of proline was better than the seed treatment in improving root dry weight, root length, chlorophyll a, carotenoids, glycine betaine, ascorbic acid and superoxide dismutase activity, whereas seed pre-treatment with proline was effective in improving shoot dry weight, shoot length, hydrogen peroxide, malondialdehyde, and peroxidase activity in both quinoa cultivars.

Influence of Glycine Betaine (Natural and Synthetic) on Growth, Metabolism and Yield Production of Drought-Stressed Maize (Zea mays L.) Plants

“…In the current experiment, both maize cultivars showed increased levels of leaf proline and glycine betaine under drought stress conditions. Generally, a high accumulation of GB or proline is considered as a prospective indicator of stress tolerance [9,10,53]. Moreover, in this experiment, foliar application of SBE and GB increased the concentration of these osmolytes in both maize cultivars under drought conditions.…”

“…Organic osmolytes, such as proline and GB, are known to maintain the water potential of cells, protect macromolecules and enzymes from oxidative damage, increase activities of enzymes, reduce the concentration of H 2 O 2 and improve the tolerance of plants against oxidative stress conditions [51][52][53]. In the current experiment, both maize cultivars showed increased levels of leaf proline and glycine betaine under drought stress conditions.…”

Quinoa for the Brazilian Cerrado: Agronomic Characteristics of Elite Genotypes under Different Water Regimes

“…The accumulation of compatible solutes reduces cellular osmotic potential, thereby permitting water absorption and maintaining turgor pressure and physiological processes [ 57 ]. The accumulation of proline may therefore be an important characteristic for the selection of drought-tolerant plants [ 58 ] and indeed seed or leaf treatment of quinoa plants with free proline can increase growth under water stress [ 59 ] whilst a number of studies have connected compatible proline accumulation with drought and salt tolerance in this species [ 49 ]. However, whilst we detected increased proline concentrations in quinoa in response to water stress, this only occurred under the most severe water regimes, meaning that it could not be used to discriminate between the genotypes under water regimes that reflect Cerrado conditions ( Table S2 ).…”

Induction of Catharanthus roseus Secondary Metabolites When Calotropis procera Was Used as Bio-Stimulant

“…The enzymatic potential of leaves and root was detected by screening the activities of catalase (CAT; EC 1.11.1.6, u mg −1 protein g −1 FW min −1 ), ascorbate peroxidase (APX; EC 1.11.1.11, µmol mg −1 protein g −1 FW min −1 ), polyphenol oxidase (PPO/EC 1.10.3.1, u mg −1 protein g −1 FW min −1 ), guaiacol peroxidase (POD; EC 1.11.1.7, µmol mg −1 protein g −1 FW min −1 ), phenylalanine ammonialyase (PAL; EC 4.3.1.5, µmol mg −1 protein g −1 FW min −1 ) and glutathione-S-transferase (GST; EC 2.5.1.18, u mg −1 protein g −1 FW min −1 ) by following the methods adopted by Martinez et al [ 34 ], Yaqoob et al [ 35 ], Tatiana et al [ 36 ], Parmeggiani et al [ 37 ], Al-Zahrani et al [ 38 ] and AbdElgawad et al [ 39 ], respectively.…”