Integrated transcriptomic and metabolomic analyses reveal key mechanisms of selenium and melatonin in enhancing tea plant resistance to gray blight disease

Authors: WANG, PANPAN - Anhui Agricultural University; ZANG, HUAWEI - Hefei University; FAROOQ, MUHAMMAD RAZA - Anhui Agricultural University; ZHOU, YANRU - Anhui Agricultural University; ZHANG, XIANLIN - Anhui Agricultural University; YIN, XUEBIN - Anhui Academy Of Agricultural Sciences; LIN, ZHIQING - Southern Illinois University; Banuelos, Gary; REITER, RUSSEL - University Of Texas Health Science Center; LI, MIAO - Anhui Agricultural University

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2025
Publication Date: 5/30/2026
Citation: Wang, P., Zang, H., Farooq, M., Zhou, Y., Zhang, X., Yin, X., Lin, Z., Banuelos, G.S., Reiter, R., Li, M. 2026. Integrated transcriptomic and metabolomic analyses reveal key mechanisms of selenium and melatonin in enhancing tea plant resistance to gray blight disease. Postharvest Biology and Technology. 12(6):1492-1504. https://doi.org/10.1016/j.hpj.2025.09.002.
DOI: https://doi.org/10.1016/j.hpj.2025.09.002

Interpretive Summary: The pear is a widely cultivated fruit tree species. Its fruit is the most consumed fruit after grape and apple worldwide because of its flavor and rich nutritional value. However, pear fruit is highly susceptible to a diverse range of pests and diseases that can significantly impact fruit yield and quality, as well as shelf-life. Among the diseases, fruit rot is caused by fungus that is considered as one of the most severe diseases in major pear-cultivation areas, occurring at pre- and post-harvest. Up to now, chemical fungicides have been the primary control strategy of this disease at postharvest. However, public concerns about protecting food and environment safety, together with the conservation of biodiversity and pathogen resistance to many key fungicides have led to an urgent need to develop alternative and eco-friendly strategies to control this disease. In this study, harvested pear fruit were infected with a fruit fungus and then treated with solutions containing both selenium (Se) and melatonin (MT). Seven days after application of Se, MT, and Se and MT, respectively, observations were recorded for severity of fruit rot and additional measurements of potential rot resistant mechanisms were identified in the fruit. We found that the combined treatment of Se and MT was most effective in helping pear fruit both resist fungus infection and stimulate the formation of defensive compounds to resist the fungus. In conclusion, it appears that the joint application of Se and MT may be an eco-friendly and nonchemical strategy for the pear industry to inhibit fruit rot in pears caused by the fruit rot fungus.

Technical Abstract: Pear (Pyrus spp.) fruit are highly susceptible to anthracnose caused by the fungus Colletotrichum fructicola, resulting in significant economic losses and raising food safety concerns. To prevent the spread of this fungus, both plant application of selenium (Se) and the phytohormone melatonin (MT) have been suggested as a combined strategy to enhance disease resistance in pears. Melatonin (MT) is a multi-functional signaling molecule, which acts as plant growth regulator and plant biostimulant that improves abiotic and biotic stress tolerance in plants, while Se can improve plant health and resistance to abiotic stresses. In this study, the antifungal effects of combining Se and MT against the fungus C. fructicola were evaluated on pears (Pyrus bretschneideri Rehd. cv. Dangshan Su) both in vitro and in vivo. Their combined impact on physiological, biochemical, and transcriptomic activities were investigated on postharvest fungi resistance mechanisms in pear fruit. Fruits of uniform maturity, size, with no visible injuries or decay were harvested at the commercial maturity stage in Anhui Province, China. In each fruit, three equatorial wounds (3 mm in diameter) were made using a sterile iron nail, and 20 µL of C. fructicola spore suspension (1×106 spores/mL) was applied per wound. Each wound was treated with 20 µL of a Se solution containing sodium selenite (10, 20, 40, 80, 100 mg/L Se) and concentrations of MT (0, 10, 20, 30, 40, 50, and 60 mg/L), based on preliminary experiments. Fruits treated with sterile distilled water served as controls. After air-drying, each wound was inoculated with 15 µL of C. fructicola conidial suspension (5 × 104 spores/mL). Treated fruits were incubated at 25' with ~95% relative humidity, and lesion diameters were measured after 7 days. Results showed that the combination of Se and MT treatment had significant inhibitory effects on the fungal disease and severity of pear anthracnose, and effectively inhibited mycelial growth, spore germination and germ tube elongation of C. fructicola in vitro. In addition, transcriptomic and proteomics analyses revealed that the Se and MT treatment promoted flavonoid biosynthesis and jasmonic acid (JA) signal activation in pear fruit. Moreover, the Se and MT treatment induced the accumulation of reactive oxygen species (ROS), affecting the expression of flavonoid biosynthesis-related genes and JA pathway-related genes. These findings suggest that Se and MT treatments, particularly in combination with one another, effectively induced ROS production, which likely contributes to the inhibition of anthracnose progression in pear fruit. In conclusion, Se treatment can independently inhibit the mycelial growth of C. fructicola, while MT had no significant inhibitory effect on mycelial growth. The combination of Se and MT, however, had a synergistic inhibitory effect and effectively controlled the expansion of anthracnose on pear fruits.