Portal de Periódicos da CAPES

Effects of Phomopsis longanae Chi Infection on Browning and Active Oxygen Metabolism in Pericarp of Harvested Longan Fruits

2011; Linguagem: Inglês

0578-1752

Zhao Yun-feng,

Plant Physiology and Cultivation Studies

【Objective】 The effects of Phomopsis longanae Chi infection on browning and active oxygen metabolism in pericarp of harvested longan fruits were investigated in this paper.【Method】 The harvested longan fruits were inoculated with Phomopsis longanae Chi for 5 min(the concentration was 104 spores per milliliter),while the control fruits were dipped in sterile water.The treated fruits were stored at(28?1)℃ and 90% relative humidity.During fruit storage,fruit disease index,pericarp browning index,malondialdehyde(MDA) content,production rate,activities of active oxygen scavenging enzymes such as superoxide dismutase(SOD),catalase(CAT) and ascorbate peroxidase(APX),contents of endogenous antioxidant substances such as ascorbic acid(AsA) and glutathione(GSH) were determined.【Result】 As compared to the control fruits there were higher fruit disease index and pericarp browning index of harvested longans infected with Phomopsis longanae Chi.The longan fruits infected with Phomopsis longanae Chi resulted in an increase of production rate and kept higher production rate in pericarp during the whole infection.There were obvious decreases of GSH content and APX activity,whereas,there were sharp increases of activities of SOD and CAT in pericarp of longans during infection from day 0 to day 2.During infection from day 2 to day 5,APX activity of pericarp rapidly increased,while the activities of SOD and CAT declined rapidly.After infection for 5 days,the rapid decreases of activities of SOD and APX in pericarp were observed.The amount of AsA in pericarp significantly decreased while MDA content increased during the whole infection.【Conclusion】 The results suggest that Phomopsis longanae Chi-induced browning of longan pericarp may be due to a decrease of active-oxygen-scavenging capacity and accumulating large amounts of reactive oxygen species,which may destroy cellular membrane structure,in turn,may cause cellular de-compartmentation,resulted in polyphenol oxidase(PPO) to come into contact with phenolic substrates and oxidation phenolics to form brown polymers.