β-Aminobutyric Acid And Nitric Oxide Treatment Induce Resistance Of Mango Fruit To Postharvest Anthracnose Caused By Colletotrichum Gloeosporioides

Mango (Mangifera indica Linn.) is one of the important tropical and subtropical fruits, However, mango is highly susceptible to postharvest decay caused by various pathogens, leading to major economic losses. One of the most destructive postharvest diseases is anthracnose caused by Colletotrichum gloeosporioides (Penz.) Sacc. in mango fruit. Disease control is achieved primarily by postharvest application of fungicides such as prochloraz and carbendazim, alone or in combination with other treatments. However, because of problems related to fungicide toxicity, development of fungicide resistance by pathogens and potential adverse effects on the environment and human health, alternative strategies for controlling postharvest rot have been proposed. Induction of resistance to pathogens in harvested crops using physical, biological, and chemical elicitors is becoming a promising approach for controlling postharvest diseases as an alternative to fungicides. The effect of β-aminobutyric acid (BABA) and sodium nitroprusside (SNP) on control of anthracnose caused by C. gloeosporioides in mango fruit and its possible mechanisms were investigated. The results are as follows:1. BABA at concentrations of25-400mM and SNP at concentrations of0.005-4mM did not significantly influence the mycelial growth and spore germination of C. gloeosporioides in vitro.2. BABA treatment and NO treatment effectively reduced the lesion diameter of anthracnose caused by C. gloeosporioides during storage.100mM BABA treatment mango fruit with lesion diameters on7days after inoculation was33.6%lower than that of control, The lesion diameters at8days in NO-treated fruit averaged30.7%lower than those in control fruit.3. BABA treatment at100mM enhanced the activities of β-1,3-glucanase (GLU), chitinase (CHT) and phenylalanine ammonia lyase (PAL), as well as promoted the gene expression of GLU, CHT and PAL.4. BABA treatment also contributed to the accumulation of hydro-gen peroxide (H2O2), while decreasing the rate of superoxide radical (O2) production Concurrently, BABA increased the activity of superoxide dismutase (SOD), while inhibiting catalase (CAT) and ascorbateperoxidase (APX) activities.5. NO treatment enhanced the activities of defense-related enzymes including phenylalanine ammonia-lyase (PAL),cinnamate-hydroxylase (C4H),4-coumarate:CoA ligase (4CL), peroxidase (POD),β-1,3-glucanase (GLU) and chitinase (CHT). 6. NO treatment also promoted the accumulation of total phenolics, flavonoids and lignin that might contribute to inhibition of the pathogen. In addition to antifungal efficacy, NO treatment delayed flesh softening, yellowing, and changes in soluble solids content (SSC) and titratable acidity (TA), and peaks of respiration rate and ethylene production during ripening.