Water Influx through the Wetted Surface of a Sweet Cherry Fruit: Evidence for an Associated Solute Efflux.

Andreas Winkler,Deborah Riedel,Moritz Knoche,Daniel Alexandre Neuwald

doi:10.3390/plants9040440

Andreas Winkler, Deborah Riedel + Show 2 more

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https://doi.org/10.3390/plants9040440

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Abstract

Sweet cherries are susceptible to rain-cracking. The fruit skin is permeable to water, but also to solutes. The objectives of this study were to (1) establish whether a solute efflux occurs when a sweet cherry fruit is incubated in water; (2) identify the solutes involved; (3) identify the mechanism(s) of efflux; and (4) quantify any changes in solute efflux occurring during development and storage. Solute efflux was gravimetrically measured in wetted fruit as the increasing dry mass of the bathing solution, and anthocyanin efflux was measured spectrophotometrically. Solute and anthocyanin effluxes from a wetted fruit and water influx increased with time. All fluxes were higher for the cracked than for the non-cracked fruit. The effluxes of osmolytes and anthocyanins were positively correlated. Solute efflux depended on the stage of development and on the cultivar. In ‘Regina’, the solute efflux was lowest during stage II (25 days after full bloom (DAFB)), highest for mid-stage III (55 DAFB), and slightly lower at maturity (77 DAFB). In contrast with ‘Regina’, solute efflux in ‘Burlat’ increased continuously towards maturity, being 4.8-fold higher than in ‘Regina’. Results showed that solute efflux occurred from wetted fruit. The gravimetrically determined water uptake represents a net mass change—the result of an influx minus a solute efflux.

Highlights

Rain cracking of sweet cherry is a serious economic problem in many regions of the world, where this high-value crop is produced [1,2]
In ‘Regina’, the solute efflux was lowest during stage II (25 days after full bloom (DAFB)), highest for mid-stage III
The low cell turgor in grape berries is thought to result from the high concentration of osmolytes in the cell-wall free space

Summary

Introduction

Rain cracking of sweet cherry is a serious economic problem in many regions of the world, where this high-value crop is produced [1,2]. The cuticle of the sweet cherry fruit is permeable to water and, to a lesser extent, to small polar molecules, such as glucose and fructose [5]. The low cell turgor in grape berries is thought to result from the high concentration of osmolytes in the cell-wall free space (apoplast). This almost eliminates any osmotic potential difference across the plasma membrane (i.e., between the apoplast and the symplast) and, the cell turgor [9,10,11,12].

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