Abstract: To clarify the synergistic effect between salicylic acid (SA) and nitric oxide (NO) in inducing resistance against anthracnose in postharvest mango fruit, the effects of single and combined treatment with 2 mmol/L SA and 0.25 mmol/L sodium nitroprusside (SNP, a NO donor) were investigated on the disease incidence, lesion diameter, and disease resistance-related enzyme activities as well as substance contents in ‘Tainong’ mango fruit (Mangifera indica L.) inoculated with Colletotichum. gloeosporioides. The results showed that SA, SNP and their combination significantly reduced the growth of C. gloeosporioides, decreased malondialdehyde (MDA) accumulation, and slowed down the progression of anthracnose. In addition, the activities of resistance-associated enzymes, such as phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), cinnamate-4-hydroxylase (C4H), 4-coumarate coenzyme A ligase (4CL), polyphenol oxidase (PPO), peroxidase (POD), chitinase (CHI) and β-1,3-glucanase (GLU) were increased markedly, and the accumulation of lignin, total phenols and flavonoids was elevated. The combination of SA and SNP was more effective than either alone. The above results show that exogenous SA and SNP combination synergistically protects mango fruit from fungal infection and improves fruit resistance to postharvest diseases, which can provide useful information for reducing the disease caused by invasion of C. gloeosporioides and preserving postharvest mango fruit.

Key words: mango; disease resistance; salicylic acid; nitric oxide; synergistic effect