Selenium-Ethylene Interplay in Postharvest Life of Cut Flowers

Abstract

Selenium (Se) is considered a beneficial element in higher plants when provided at low concentrations. Recently, studies have unveiled the interactions between Se and ethylene metabolism throughout plant growth and development. However, despite the evidence that Se may provide longer shelf life in ethylene-sensitive flowers, its primary action on ethylene biosynthesis and cause-effect responses are still understated. In the present review, we discuss the likely action of Se on ethylene biosynthesis and its consequence on postharvest physiology of cut flowers. By combining Se chemical properties with a dissection of ethylene metabolism, we further highlighted both the potential use of Se solutions and their downstream responses. We believe that this report will provide the foundation for the hypothesis that Se plays a key role in the postharvest longevity of ethylene-sensitive flowers.

Keywords: Se metabolism; ethylene inhibitors; flower quality; preservative solutions; vase life.

FIGURE 1

Model for Se-induced ethylene biosynthesis downregulation in a cut flower system. Firstly, Se is provided as selenate – the main transported form in the xylem. In petal cells, selenate is converted to selenite and subsequently to Se-homocysteine by a series of enzymatic reactions. In a third stage, Se-homocysteine forms SeMet, reducing free Met levels toward to biosynthesis ethylene pathway. This event affects subsequently SAMS and ACS activities by reducing substrate (Met) availability to sustain ethylene biosynthesis pathway. Finally, the decreased ethylene biosynthesis may lead to the maintenance of overall quality on the postharvest life of cut flowers. Ethylene biosynthesis pathway: ACC, 1-aminocyclopropane-1-carboxylate; ACS, ACC synthase; MTR, S-methyl-5-thio-D-ribose; MTA, S-methyl-5′-this adenosine; KMB, 2-keto-4-methylthiobutyrate; Se, Selenium; SAM, S-adenosylmethionine; SAM synthetase, SAMS; HCN, Hydrogen cyanide; CO₂, Carbon dioxide; O₂, Oxygen; Met, Methionine; Pi, inorganic phosphate; and PPi, inorganic pyrophosphate. Se metabolism: Se, Selenium; SeCys, selenocysteine; SeMet, selenomethionine. *Enzymatic reaction.