Postharvest physiological disorders in citrus fruit

Abstract

Purpose of the review: Various types of postharvest physiological disorders have been described in citrus fruit, but how they are related to each other is not understood. We still lack knowledge of mechanisms governi ng them and appropriate methods for red ucing their incidence. The purpose of this review is to give an overview of the most important postharvest physiological disorders occurri ng in citrus fruit and the efficacy of different methods used for cont rolling them, and to outline the physiological and molecular basis of the different types of rind disorders. Recent findings: E fforts have been made in recent years to reveal factors responsible for different postha rvest citrus disorders and to develop new strategies to control them. Special attempts has been made to understand the physiological and biochemical b asis of low temperature tolerance in citrus, including the role o f plant hormones, alteration in lipids, carbohydrate and phenylp ropanoid metabolism, and in oxidative stress-associated processes. Mo lecular events by which citrus fruit may tolerate chilling are in their early stages, however, recent studies have shown the complexity of the molecular mechanism underlying chilling t olerance, w hich requires expression of transcription factors, activatio n of secondary metabolism and stress-related proteins. In co ntrast, information on the mechanism governing other non-ch illing related physiological d isorders is still scarce. Directions for future research: Furthe r work is necessary to understand the precise ca use of the postharvest alterations occurring in each cultivar and to implement successful commercial posth arvest treatments to control them. To obtain a general picture o f the nature of the main postharvest disorders in citrus, it i s necessary to delineate the precise fu nction of the identified phy siolo gical and molecular disorder-associated responses. The availab ility of new high throughput molecular strategies and comprehensive c DNA libraries from rind citrus fruit tissues will provi de excellent tools to c ontinue the study of the mechanisms underlyin g them. This knowledge will lead to improvements in the technologies used to maintain external fruit quality and to reduce su bsequent commercial losses of citrus fruit.