Involvement of Secondary Metabolites in Response to Drought Stress of Rice (Oryza sativa L.)

Abstract

Abstract:In this study, responses of rice under drought stress correlating with changes in chemical compositions were examined. Among 20 studied rice cultivars, Q8 was the most tolerant, whereas Q2 was the most susceptible to drought. Total phenols, total flavonoids, and antioxidant activities, and their accumulation in water deficit conditions were proportional to drought resistance levels of rice. In detail, total phenols and total flavonoids in Q8 (65.3 mg gallic acid equivalent (GAE) and 37.8 mg rutin equivalent (RE) were significantly higher than Q2 (33.9 mg GAE/g and 27.4 mg RE/g, respectively) in both control and drought stress groups. Similarly, the antioxidant activities including DPPH radical scavenging, β-carotene bleaching, and lipid peroxidation inhibition in Q8 were also higher than in Q2, and markedly increased in drought stress. In general, contents of individual phenolic acids in Q8 were higher than Q2, and they were significantly increased in drought stress to much greater extents than in Q2. However, p-hydroxybenzoic acid was found uniquely in Q8 cultivars. In addition, only vanillic acid was found in water deficit stress in both drought resistant and susceptible rice, suggesting that this phenolic acid, together with p-hydroxybenzoic acid, may play a key role in drought-tolerance mechanisms of rice. The use of vanillic acid and p-hyroxybenzoic acid, and their derivatives, may be useful to protect rice production against water shortage stress.

Changes in phenolic acid abundance involved in low temperature and Microdochium nivale (Samuels and Hallett) cross-tolerance in winter triticale (x Triticosecale Wittmack)

“…The metabolic changes in level of foliar phenolics and increased PAL activity during cold acclimation in androgenic forms of Festulolium were observed in frost-tolerant and snow mould-tolerant (cross-tolerant) genotypes (Pociecha et al 2008). A rise of the cell wallbound phenolics concentration was also correlated with the productivity of triticale (Hura et al 2012) and rice (Quan et al 2016) under soil drought. Furthermore, during the microscopic analysis, the cell wall-phenolics accumulated in sites of M. nivale invasion in winter triticale , Lolium perenne (Dubas et al 2010) and winter rye (Żur et al 2011) seedlings.…”

Imposed Water Deficit after Anthesis for the Improvement of Macronutrients, Quality, Phytochemicals, and Antioxidants in Rice Grain

“…It was estimated that 50% of the rice production can be affected by drought [25]. Thus, there have been many studies conducted with attempts to breed rice cultivars tolerant to drought [26], as well as proper water use in rice production against drought [6]. In addition, a number of new rice varieties have been bred and released yearly with higher yield potential and stronger resistance to abiotic and biotic stresses.…”

Involvement of Phenolic Compounds in Anaerobic Flooding Germination of Rice (<i>Oryza sativa</i> L.)

“…Phenolics are not the main factor to assist rice to escape from flooding condition or shoot elongation, but the high accumulation of such secondary metabolite partly protects plant cells from physical injuries during exposure to stress conditions, especially submergence. For instance, Quan et al [22] reported the presence of only-hydroxybenzoic acid in the tolerant rice variety after drought stress treatment.…”