Exogenous melatonin confers drought stress by promoting plant growth, photosynthetic capacity and antioxidant defense system of maize seedlings

PeerJ. 2019 Oct 11:7:e7793. doi: 10.7717/peerj.7793. eCollection 2019.

Abstract

Melatonin is an important biologically active hormone that plays a vital role in plant growth and development. In particular, it has been investigated for its roles in abiotic stress management. The current experiment was carried out to investigate the protective role of melatonin in photosynthetic traits and the antioxidant defense system of maize seedling under drought stress. Maize seedlings were subjected to drought stress (40-45% FC) after two weeks of seedling emergence, followed by a foliar spray (0, 25, 50, 75 and 100 µM) and soil drench of melatonin (0, 25, 50, 75 and 100 µM). Our results indicated that drought stress negatively affected maize seedling and decreased plant growth and development, biomass accumulation, reduced chlorophyll, and carotenoid content, and significantly declined photosynthetic rate and stomatal conductance. On the other hand, reactive oxygen species, soluble protein, and proline content increased under drought stress. However, the application of exogenous melatonin reduced the reactive oxygen species burst and enhanced the photosynthetic activity by protecting from damages through activation of various antioxidant enzymes under drought stress. Foliar application of 100 µM and soil drench of 50 µM melatonin was the most effective treatment concentrations under drought stress. Our current findings hereby confirmed the mitigating potential of melatonin application for drought stress by maintaining plant growth, improving the photosynthetic characteristics and activities of antioxidants enzymes.

Keywords: Antioxidants; Biomass; Chlorophyll; Drought; Melatonin; Photosynthesis.

Grants and funding

This study was supported by funding from the High Technology Research and Development Program of China (863 Program, No.2013AA102902), the National Natural Science Foundation of China (No. 31601256), the special fund for Agro-scientific Research in the Public Interest (201303104), and the 111 Project of Chinese Education Ministry (B12007). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.