Effects of exogenous calcium on the drought response of the tea plant ( Camellia sinensis (L.) Kuntze)

• Published in: PeerJ (San Francisco, CA) CA), 2022-08, Vol.10, p.e13997-e13997, Article e13997
• Main Authors: Malyukova, Lyudmila S, Koninskaya, Natalia G, Orlov, Yuriy L, Samarina, Lidiia S
• Format: Article
• Language: English
• Subjects: Abscisic acid; Agricultural Science; Ammonium; Ammonium compounds; Ammonium nitrate; Ammonium paratungstate; Analysis; Biotechnology; Calcium - metabolism; Calcium nitrate; Camellia sinensis; Camellia sinensis - genetics; Catechin; Cell membranes; Crops; Cultivars; Drought; Drought stress; Droughts; Electric properties; Electrical conductivity; Electrolyte leakage; Environmental conditions; Exogenous calcium; Gene expression; Genetics; Humidity; Leaves; Magnesium; Methionine; pH effects; Physiological aspects; Physiology; Plant physiology; Plant Science; Plant transcription factors; Russia; Signal transduction; Soil Science; Stomata; Tea - metabolism; Tea plant; Transcription factors; Tyrosine; Valine
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.13997

Drought is one of the major factors reducing the yield of many crops worldwide, including the tea crop ( (L.) Kuntze). Calcium participates in most of cellular signaling processes, and its important role in stress detection and triggering a response has been shown in many crops. The aim of this study was to evaluate possible effects of calcium on the tea plant response to drought. Experiments were conducted using 3-year-old potted tea plants of the best local cultivar Kolkhida. Application of ammonium nitrate (control treatment) or calcium nitrate (Ca treatment) to the soil was performed before drought induction. Next, a 7-day drought was induced in both groups of plants. The following physiological parameters were measured: relative electrical conductivity, pH of cell sap, and concentrations of cations, sugars, and amino acids. In addition, relative expression levels of 40 stress-related and crop quality-related genes were analyzed. Under drought stress, leaf electrolyte leakage differed significantly, indicating greater damage to cell membranes in control plants than in Ca-treated plants. Calcium application resulted in greater pH of cell sap; higher accumulation of tyrosine, methionine, and valine; and a greater Mg content as compared to control plants. Drought stress downregulated most of the quality-related genes in both groups of tea plants. By contrast, significant upregulation of some genes was observed, namely , , , , , , , , , , , , , and . Among them, three genes ( , , and ) showed 2-3 times greater expression in Ca-treated plants than in control plants. Based on these results, it can be speculated that calcium affects galactinol biosynthesis and participates in the regulation of stomatal aperture not only through activation of abscisic-acid signaling but also through jasmonic-acid pathway activation. These findings clarify calcium-mediated mechanisms of drought defense in tree crops. Thus, calcium improves the drought response in the tea tree.