Investigation of an Antioxidative System for Salinity Tolerance in Oenanthe javanica

Abstract

Abiotic stress, such as drought and salinity, severely affect the growth and yield of many plants. Oenanthe javanica (commonly known as water dropwort) is an important vegetable that is grown in the saline-alkali soils of East Asia, where salinity is the limiting environmental factor. To study the defense mechanism of salt stress responses in water dropwort, we studied two water dropwort cultivars, V11E0022 and V11E0135, based on phenotypic and physiological indexes. We found that V11E0022 were tolerant to salt stress, as a result of good antioxidant defense system in the form of osmolyte (proline), antioxidants (polyphenols and flavonoids), and antioxidant enzymes (APX and CAT), which provided novel insights for salt-tolerant mechanisms. Then, a comparative transcriptomic analysis was conducted, and Gene Ontology (GO) analysis revealed that differentially expressed genes (DEGs) involved in the carbohydrate metabolic process could reduce oxidative stress and enhance energy production that can help in adaptation against salt stress. Similarly, lipid metabolic processes can also enhance tolerance against salt stress by reducing the transpiration rate, H2O2, and oxidative stress. Furthermore, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that DEGs involved in hormone signals transduction pathway promoted the activities of antioxidant enzymes and reduced oxidative stress; likewise, arginine and proline metabolism, and flavonoid pathways also stimulated the biosynthesis of proline and flavonoids, respectively, in response to salt stress. Moreover, transcription factors (TFs) were also identified, which play an important role in salt stress tolerance of water dropwort. The finding of this study will be helpful for crop improvement under salt stress.

Effect of Salt Stress on Growth, Physiological Parameters, and Ionic Concentration of Water Dropwort (Oenanthe javanica) Cultivars

“…In the current study, a minor decrease in MDA concentration was observed at 200 mm NaCl in the leaves of both cultivars. 200 mm NaCl might induces salt stress-related genes in the leaves of water dropwort ( Kumar et al, 2020 ). Sustained decreases in MDA accumulation might be due to the activation of PSII core proteins and Rubisco ( Morales and Munné-Bosch, 2019 ).…”

“…Relative water content (RWC) of leaves was measured according to the method described by Sarker and Oba (2018) and Kumar et al (2020) . After determining the fresh weight (FW), leaves were immersed in distilled water in a closed Petri dish for 4 h, and the turgor weight (TW) of each leaf was noted.…”

“…It is mainly cultivated in East Asian countries, such as China, Japan, Korea, Thailand, Malaysia, and Australia ( Jeon et al, 2007 ; Lee and Kim, 2009 ; Lu and Li, 2019 ). Water dropwort contains high contents of minerals and vitamins, and demonstrates medicinal properties ( Jiang et al, 2015 ; Lu and Li, 2019 ; Kumar et al, 2020 , 2021 ). It has been traditionally used as a vegetable in China.…”

“…Therefore, all these properties make the water dropwort a popular edible plant in China. The previous studies reported that O. javanica is sensitive to drought and salt stress, and these are the key limiting factors for its growth and production ( Jiang et al, 2015 ; Kumar et al, 2020 ). There is only limited information available related to the salt tolerance mechanism of water dropwort concerning the regulation of free radicals quenching pathway with the antioxidative defense.…”

Combined Transcriptomic and Metabolomic Analysis Reveals the Role of Phenylpropanoid Biosynthesis Pathway in the Salt Tolerance Process of Sophora alopecuroides

“…We measured the chlorophyll content of salt-treated S. alopecuroides and found that the recovery upregulation occurred at 24 h and 48 h, thereby indicating that S. alopecuroides reduced the influence of salt stress on photosynthesis. Sugars are photosynthates and respiration substrates [ 39 , 40 ], and they provide a carbon skeleton and energy for plant growth. An increase in the soluble sugar content improves cell osmotic regulation and protoplasm protection [ 34 , 38 ].…”