Combined treatment with hot water and UV-C elicits disease resistance against anthracnose and improves the quality of harvested mangoes Kanlaya Sripong a, b , Pongphen Jitareerat a, b, * , Shinji Tsuyumu c , Apiradee Uthairatanakij a, b , Varit Srilaong a, b , Chalermchai Wongs-Aree a, b , Gang Ma c , Lancui Zhang c , Masaya Kato c a Postharvest Technology Program, School of Bioresources and Technology, King Mongkut's University of Technology Thonburi,126 Bangmod, Thungkru, Bangkok 10140, Thailand b Postharvest Technology Innovation Center, Commission of Higher Education, Bangkok 10400, Thailand c Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan article info Article history: Received 12 January 2015 Received in revised form 25 June 2015 Accepted 4 July 2015 Available online xxx Keywords: Colletotrichum gloeosporioides Penz. Chitinase UV-C irradiation Peroxidase Phenylalanine ammonia lyase b-1,3-glucanase abstract This research investigated the effects of hot water, UV-C irradiation and their combination on the in- duction of resistance to anthracnose disease and on quality improvement in harvested mangoes. Naturally infected mango fruits were harvested, surface-disinfested with a solution of 100 ppm sodium hypochlorite and air dried. The fruits were then treated with UV-C irradiation at a dose 6.16 kJ m 2 , with hot water at 55  C for 5 min or with hot water followed by UV-C irradiation. Untreated fruits served as the control. All fruit samples were kept at 13  C for 12 days. The combined treatment significantly suppressed the severity of anthracnose symptoms compared with either single treatment. Additionally, the specific activities of key plant defense-related enzymes, such as phenylalanine ammonia lyase (PAL), peroxidase (POD), chitinase (CHI) and b-1,3-glucanase (GLU), increased in both the peel and the pulp of the mango fruits. The expressions of the MI-PAL, MI-POD, MI-CHI and MI-GLU genes in the mango peel were markedly enhanced in the fruits treated with the combined treatment in comparison with those treated with hot water or UV-C alone, while the control fruits showed the lowest expression of these genes. The combined treatment or UV-C treatment alone significantly delayed fruit ripening by main- taining fruit firmness, retarding the progressive increase of total soluble solids (TSS) and delaying the decrease in titratable acidity (TA). Weight loss was not significantly different among the treatments. The results suggested that the combination of hot water and UV-C treatment may be used as a tool not only for suppressing anthracnose disease but also for improving the quality of harvested mangoes by inducing the expression of plant defense-related genes. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Mangoes (Mangifera indica L.) are among the most popular tropical fruits. However, mango fruit is susceptible to various dis- eases, especially to anthracnose disease caused by the fungus Col- letotrichum gloeosporioides Penz. Application of fungicides, such as prochloraz and mancozeb, is usually used to control anthracnose disease (Arauz, 2000). Fungicide-resistant strains occur when fungicides are used frequently for long periods. In addition, con- sumers are currently concerned about the risks of chemical resi- dues on agricultural products. Recently, many researchers have attempted to replace chemical treatments with alternative and safer technologies. Hot water treatment is one of the most prom- ising non-fungicide technologies and quarantine treatment for controlling postharvest diseases. Hot water treatment can be applied effectively to suppress certain important postharvest pathogens in a number of fruits, such as Penicillium expansum on pears (Zhang et al., 2008), Penicillium digitatum Sacc. on lemon fruits (Nafussi et al., 2001), C. gloeosporioides on papaya fruits (Li * Corresponding author. Postharvest Technology Program, School of Bioresources and Technology, King Mongkut's University of Technology Thonburi,126 Bangmod, Thungkru, Bangkok 10140, Thailand. E-mail address: pongphen.jit@kmutt.ac.th (P. Jitareerat). Contents lists available at ScienceDirect Crop Protection journal homepage: www.elsevier.com/locate/cropro http://dx.doi.org/10.1016/j.cropro.2015.07.004 0261-2194/© 2015 Elsevier Ltd. All rights reserved. Crop Protection 77 (2015) 1e8