title: The effect of delay between heat treatment and cold storage on alleviation of chilling injury in banana fruit.
abstract: BACKGROUND
  To understand the mechanisms leading to the enhanced chilling resistance of banana by hot-water dipping (HWD, 52 °C for 3 min), we investigated the effect of a 0.5-24 h delay between HWD and cold storage on chilling resistance and the change related to the metabolism of reactive oxygen species (ROS).
  
  
  RESULTS
  The HWD-treated fruit with a delay of less than 6 h exhibited markedly less chilling injury than the non-heated control fruit, while a delay more than 6 h resulted in significant loss in chilling resistance. Increased hydrogen peroxide content and rate of superoxide radical production were detected in the fruit at 0.5-1.5 h after HWD treatment, and the levels declined with a longer delay, which may be correlated with the enhanced gene expression levels of the gene coding for a ROS-generating related enzyme, NADPH oxidase (MaNOX). Enhanced activities and gene expression of an ascorbate peroxidase (MaAPX) were recorded in the fruit at 1.5-6 h after the treatment, and after 6 h the ascorbate peroxidase levels decayed to the levels as the control fruit. The higher APX gene expression was maintained in the treated fruit with a 3 h delay during the subsequent cold storage at 7 °C, correlating with the enhanced chilling resistance.
  
  
  CONCLUSIONS
  The HWD-treated fruit left at ambient temperature up to 6 h prior to cold storage maintained the effect of heat treatment and transiently increased ROS content, and the ascorbate peroxidase activity that occurred 0.5-6 h after the treatment may be correlated with the elevated chilling resistance induced by HWD treatment.
authors.affiliation: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources South China Agricultural University, Guangzhou, China.
authors.forename: Haibo
authors.initials: H
authors.lastname: Wang
authors.forename: Zhaoqi
authors.initials: Z
authors.lastname: Zhang
authors.forename: Lanying
authors.initials: L
authors.lastname: Xu
authors.forename: Xuemei
authors.initials: X
authors.lastname: Huang
authors.forename: Xuequn
authors.initials: X
authors.lastname: Pang
mesh_terms: D060387:Ascorbate Peroxidases / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D005519:Food Preservation / Q000379:methods; D061353:Food Storage / Q000379:methods; D005638:Fruit / Q000201:enzymology / Q000378:metabolism*; D015870:Gene Expression; D006358:Hot Temperature; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D028521:Musa / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D017382:Reactive Oxygen Species; D013481:Superoxides; D006861:Hydrogen Peroxide; D060387:Ascorbate Peroxidases; D019255:NADPH Oxidases