Physiological and Biochemical Response of Tropical Fruits to Hypoxia/Anoxia.

Noureddine Benkeblia

doi:10.3389/fpls.2021.670803

Abstract

Aerobic respiration and oxygen consumption are indicators of routine metabolic rate, and dissolved oxygen in plant tissues is one of the most important environmental factors affecting their survival. The reduction of available O2 leads to hypoxia which causes a limitation of the oxidative phosphorylation; when O2 is absent, tissues generate ATP by activating the fermentative glycolysis to sustain glycolysis in the absence of mitochondrial respiration, which results in the production of lactate. Overall, hypoxia was reported to often decrease the respiration rate (O2 uptake) and delay the climacteric rise of ethylene in climacteric fruits by inhibiting action, thus delaying their ripening. Much research has been done on the application of postharvest hypoxia and anoxia treatment to temperate fresh crops (controlled or modified atmosphere), however, very few reported on tropical commodities. Indeed, the physiological mode of action of low or absence of oxygen in fresh crops is not well understood; and the physiological and biochemical bases of the effects low or absence of O2 are also yet to be clarified. Recent investigations using omics technologies, however, have provided useful information on the response of fresh fruits and vegetables to this abiotic stress. The aims of this review are to (i) report on the oxygen exchange in the crops tissue, (ii) discuss the metabolic responses to hypoxia and anoxia, and (iii) report the physiological and biochemical responses of crops tissues to these abiotic stresses and the potential benefits of these environmental conditions.

Highlights

From the botanical point of view, tropical fruits are a diverse group of commodities native to tropical regions which are geographically defined as regions between the latitudes 23◦ North and South of the equator, with temperatures averaging around 27◦C and little variation in photoperiod (Samson, 1986)
This review aims to describe the effects of low oxygen availability -hypoxia/anoxia- on the physiology, the biochemistry and the quality attributes of tropical fruits in order to determine the optimal condition of modified atmosphere packaging (MAP) application in postharvest handling and storage of these commodities
On several tropical fruits low or absence of oxygen has shown its involvement in reducing the respiration rate (RR) and ethylene biosynthesis, prolonging the shelf-life of these commodities and maintaining some quality attributes and freshness

Summary

Introduction

From the botanical point of view, tropical fruits are a diverse group of commodities native to tropical regions which are geographically defined as regions between the latitudes 23◦ North and South of the equator, with temperatures averaging around 27◦C and little variation in photoperiod (Samson, 1986). Hypoxia/Anoxia and Tropical Fruits and absolute pressure of 1 atm. Under normal condition of oxygen level (normoxia) cells run aerobic respiration and energy in the form of ATP is produced by oxidative phosphorylation. A reduction in oxygen (hypoxia) reduces the oxidative phosphorylation, while the absence of oxygen (anoxia) stops the phosphorylation process (Wongs-Aree and Noichinda, 2018; Salvatierra et al, 2020). This diverts the production of energy to the fermentation pathway producing fermentative by-products that accumulate in the cells (Boersig et al, 1988; Pfister-Sieber and Brändle, 1994; Cho et al, 2021)

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Conclusion