Regulation on anthocyanins, α-tocopherol and calcium in two water spinach (Ipomoea aquatica) cultivars by NaCl salt elicitor.

Highlights • An internode length and shoot height of cv. WT were promoted by 50 mM NaCl salt elicitor. • Water spinach cv. WT was more tolerate to NaCl than cv. CT indicating by total leaf area. • Total anthocyanin, α-tocopherol and calcium content in the leaves of "WT" variety was significantly increased by 25 mM NaCl. Abstract Anthocyanins, a member of flavonoids are abundantly found in fruits, flowers, stem, leaves and seeds of many plant species. They play a vital role as an antioxidant by preventing the oxidative stress in human. Abiotic elicitors i.e. low temperature, salinity, drought, UV and nutrient deficiency have been reported as alternative channels for anthocyanin enrichment. The aim of this investigation was to elevate the content of anthocyanin, α-tocopherol and calcium ions in the leaves and stems of two varieties, "Chia Tai" (CT; green stem) and "wild type" (WT; red stem) of water spinach (Ipomoea aquatica) using NaCl elicitors without having any retardatory effect on growth parameters. Six-week-old seedlings of water spinach were treated with 0, 25, and 50 mM NaCl for 3 weeks under greenhouse conditions. Growth performances in terms of fresh weight of upper part and number of leaves in the treated plants of both the varieties were unchanged when compared to the control. Interestingly, the internode length and shoot height of cv. WT under 50 mM NaCl salt elicitor were promoted. Total leaf area in CT under 50 mM NaCl was significantly declined by 23.57% over control, whereas it was maintained in cv. WT. Na+ in the leaf and root tissues of both CT and WT was increased depending on the degree of NaCl treatment. Calcium content in the leaves of water spinach under 25 and/or 50 mM NaCl was increased in both the cultivars. Total anthocyanin content in leaves of "WT" variety grown under 25 mM NaCl was significantly increased by 35.87 folds over control condition (0 mM NaCl), whereas it was undetected in "CT" variety. α-Tocopherol in the leaf and stem tissues of "WT" under 25 mM NaCl was significantly increased by 11.28 and 2.62 folds over the "CT" cultivar. Net photosynthetic rate of "WT" variety was significantly decreased, depending on the strength of NaCl treatment. In summary, the total anthocyanin and calcium content in "WT" variety of water spinach were increased by the treatment of 50 mM NaCl elicitor without any sign of growth retardation in the treated plants. [ABSTRACT FROM AUTHOR]