Physiological mechanisms of ABA-induced salinity tolerance in leaves and roots of rice

Abstract

Abscisic acid (ABA) plays a crucial role in response to abiotic stress as important small molecules in regulating metabolism. This study aimed to evaluate the ability of foliar spraying ABA to regulate growth quality at rice seedling stage under salt stress. Results demonstrated that salt stress strongly reduced all the growth parameters of two rice seedlings (‘Chaoyouqianhao’ and ‘Huanghuazhan’), caused prominent decrease in the levels of photosynthetic pigments (mainly in Huanghuazhan), photosynthesis and fluorescence parameters. Salinity treatment increased the concentration of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in roots, whereas significant decreased H2O2 was found in leaves of Huanghuazhan. Additionally, salinity triggered high Na+ content particularly in leaves and enhanced catalase (CAT) activities, ascorbate peroxidase (APX) and peroxidase (POD) activities of the two rice seedlings. Nevertheless, salinity-induced increased root ascorbic acid (AsA) and glutathione (GSH) levels while decreased in leaves, which depended on treatment time. Conversely, ABA application partially or completely mitigated salinity toxicity on the seedlings. ABA could reverse most of the changed physiological parameters triggered by salt stress. Specially, ABA treatment improved antioxidant enzyme levels and significantly reduced the Na+ content of two varieties as well as increased the K+, Mg2+ and Ca2+ content in leaves and roots. ABA treatment increased the hormone contents of 1-aminocclopropane carboxylic acid (ACC), trans-zeatin (TZ), N6-isopentyladenosine (IPA), Indole-3-acetic acid (IAA), and ABA in leaves of two rice varieties under salt stress. It is suggested that ABA was beneficial to protect membrane lipid peroxidation, the modulation of antioxidant defense systems and endogenous hormonal balance with imposition to salt stress.

A C2-Domain Abscisic Acid-Related Gene, IbCAR1, Positively Enhances Salt Tolerance in Sweet Potato (Ipomoea batatas (L.) Lam.)

“…Under abiotic stress, genes related to the ABA signaling pathway AAO and ABA2 were induced to express and promote the rapid accumulation of ABA in plants [ 46 ]. ABA has been reported to regulate the expression levels of stress-tolerance-related genes, including APX , POD , LEA , and CAT , in several plant species [ 47 , 48 , 49 ].…”

Response mechanisms of sugarcane seedlings to the allelopathic effects of root aqueous extracts from sugarcane ratoons of different ages

“…Importantly, MDA can be used to evaluate the extent of membrane lipid peroxidation and the antioxidant capacity of tissues and cells ( Chen et al., 2022 ; Li et al., 2022 ). In the present study, the MDA content in the leaves and roots of sugarcane seedlings showed an upward trend with increasing extract concentration.…”

Effects of Exogenous (K+) Potassium Application on Plant Hormones in the Roots of Tamarix ramosissima under NaCl Stress

“…In particular, under NaCl stress, applying exogenous abscisic acid in rice reduced the Na + content in the leaves and roots, and increased the K + , Mg 2+ and Ca 2+ content and antioxidant enzyme levels in the leaves and roots, thereby reducing the salt toxicity of seedlings. It showed that ABA is beneficial for protective membrane lipid peroxidation and enhances salt tolerance by regulating antioxidant defense systems and endogenous hormone balance [ 59 ]. ABA enhances tolerance to alkaline stress by initiating antioxidant defense system in roots of rice seedlings and upregulating tolerance-related genes [ 60 ].…”