Potential of melatonin and Trichoderma harzianum inoculation in ameliorating salt toxicity in watermelon: Insights into antioxidant system, leaf ultrastructure, and gene regulation

Muhammad Imran Ghani; Benlin Yi; Muhammad Saad Rehmani; Xi Wei; Junaid Ali Siddiqui; Ruidong Fan; Yanjiang Liu; Mohamed A El-Sheikh; Xiaoyulong Chen; Parvaiz Ahmad

doi:10.1016/j.plaphy.2024.108639

Potential of melatonin and Trichoderma harzianum inoculation in ameliorating salt toxicity in watermelon: Insights into antioxidant system, leaf ultrastructure, and gene regulation

Plant Physiol Biochem. 2024 Apr 24:211:108639. doi: 10.1016/j.plaphy.2024.108639. Online ahead of print.

Authors

Affiliations

¹ College of Agriculture/College of Life Sciences, Guizhou University, Guiyang, 550025, China; Key Laboratory of Karst Georesources and Environment, Ministry of Education, College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China; Guizhou-Europe Environmental Biotechnology and Agricultural Informatics Oversea Innovation Center in Guizhou University, Guizhou Provincial Science and Technology Department, Guiyang, 550025, China; International Jointed Institute of Plant Microbial Ecology and Resource Management in Guizhou University, Ministry of Agriculture, China & China Association of Agricultural Science Societies, Guizhou University, Guiyang, 550025, China.
² College of Agriculture/College of Life Sciences, Guizhou University, Guiyang, 550025, China; Guizhou-Europe Environmental Biotechnology and Agricultural Informatics Oversea Innovation Center in Guizhou University, Guizhou Provincial Science and Technology Department, Guiyang, 550025, China; International Jointed Institute of Plant Microbial Ecology and Resource Management in Guizhou University, Ministry of Agriculture, China & China Association of Agricultural Science Societies, Guizhou University, Guiyang, 550025, China.
³ College of Agriculture/College of Life Sciences, Guizhou University, Guiyang, 550025, China.
⁴ College of Ecology and Environment, Tibet University, Lhasa 850000, China.
⁵ Botany and Microbiology Department, College of Science, King Saud University, Riyadh-11451, Saudi Arabia.
⁶ College of Agriculture/College of Life Sciences, Guizhou University, Guiyang, 550025, China; Key Laboratory of Karst Georesources and Environment, Ministry of Education, College of Resources and Environmental Engineering, Guizhou University, Guiyang, 550025, China; Guizhou-Europe Environmental Biotechnology and Agricultural Informatics Oversea Innovation Center in Guizhou University, Guizhou Provincial Science and Technology Department, Guiyang, 550025, China; International Jointed Institute of Plant Microbial Ecology and Resource Management in Guizhou University, Ministry of Agriculture, China & China Association of Agricultural Science Societies, Guizhou University, Guiyang, 550025, China; College of Ecology and Environment, Tibet University, Lhasa 850000, China. Electronic address: chenxiaoyulong@sina.cn.
⁷ Department of Botany, GDC-Pulwama-192301, Jammu and Kashmir, India. Electronic address: parvaizbot@yahoo.com.

PMID: 38688113
DOI: 10.1016/j.plaphy.2024.108639

Abstract

Melatonin (MT) is an extensively studied biomolecule with dual functions, serving as an antioxidant and a signaling molecule. Trichoderma Harzianum (TH) is widely recognized for its effectiveness as a biocontrol agent against many plant pathogens. However, the interplay between seed priming and MT (150 μm) in response to NaCl (100 mM) and its interaction with TH have rarely been investigated. This study aimed to evaluate the potential of MT and TH, alone and in combination, to mitigate salt stress (SS) in watermelon plants. The findings of this study revealed a significant decline in the morphological, physiological, and biochemical indices of watermelon seedlings exposed to SS. However, MT and TH treatments reduced the negative impact of salt stress. The combined application of MT and TH exerted a remarkable positive effect by increasing the growth, photosynthetic and gas exchange parameters, chlorophyll fluorescence indices, and ion balance (decreasing Na⁺ and enhancing K⁺). MT and TH effectively alleviated oxidative injury by inhibiting hydrogen peroxide formation in saline and non-saline environments, as established by reduced lipid peroxidation and electrolyte leakage. Moreover, oxidative injury induced by SS on the cells was significantly mitigated by regulation of the antioxidant system, AsA-GSH-related enzymes, the glyoxalase system, augmentation of osmolytes, and activation of several genes involved in the defense system. Additionally, the reduction in oxidative damage was examined by chloroplast integrity via transmission electron microscopy (TEM). Overall, the results of this study provide a promising contribution of MT and TH in safeguarding the watermelon crop from oxidative damage induced by salt stress.

Keywords: Antioxidant system; Leaf ultrastructure; Melatonin seed priming; Salt stress; Trichoderma harzianum; Watermelon.