บทคัดย่องานวิจัย

หมวดหมู่ : ฐานข้อมูลงานวิจัย

Phenylalanine-ammonia-lyase and accumulation of phenolic compounds in the ethylene-induced tolerance to rindstaining in ‘Navelate’ fruit.

Cajuste J.F., Lafuente M.T.

5th International Postharvest Symposium . Volume of Abstract . Verona, Italy 6-11 June 2004, p.53

2004

บทคัดย่อ

Phenylalanine-ammonia-lyase and accumulation of phenolic compounds in the ethylene-induced tolerance to rindstaining in ‘Navelate’ fruit.  The orange fruit cultivar ‘Navelate’ is prone to develop postharvest rindstaining(RS) during storage at non-chilling temperatures.This disorder is manifested as extensive collapsed and dried areas of the flavedo and part of the albedo.Ethylene has been shown to protect citrus fruit against RS but the mechanisms associated with the ethylene-induced tolerance to this disorder are unknown.

In this study we have examined the effect of applying ethylene, before of during holding of ‘Navelate’ fruit under postharvest conditions (22 °C, 90-95% RH) inducing RS, o­n changes in the activity of the enzyme phenylalanine-ammonia-lyase (PAL), the initial rate-controlling enzyme in the phenilpropanoid pathway, and o­n phenolic content.PAL activity increased concomitantly with albedo and flavedo damage development in control fruit maintained in air.Exogenous ethylene treatments, which efficiently reduced RS incidence, induced a sharp and great increase in PAL activity and phenolic content in both peel tissues from the beginning of the storage period, which preceded the appearance of RS in air-treated fruit.In addition, PAL and phenolic levels were, in general, higher in the ethylene-treated fruit than in those fruit kept in air during the storage period examined.

These results indicate that the induction of the enzyme PAL and of subsequent phenilpropanoid compounds may play a role in reducing the development of RS symptoms and are part of the mechanisms involved in the beneficial effect of ethylene protecting citrus fruit against this physiological disorder.Furthermore, in the present study we have evaluated weight loss, decay and internal quality and have shown that ethylene conditions that reduced RS were not deleterious for ‘Navelate’ fruit.