TY - JOUR

T1 - Swelling of cell walls in mature sweet cherry fruit

T2 - factors and mechanisms

AU - Schumann, Christine

AU - Knoche, Moritz

N1 - Funding Information: Open Access funding provided by Projekt DEAL. We thank Andreas Meyer for constructing the pressure chamber, Simon Sitzenstock for technical help, Drs. Chong Cheng and Eli Ruckenstein for useful discussion of the PEG effect and Dr. Alexander Lang for useful comments on an earlier version of this manuscript. This study was funded in part by a grant from the German Science Foundation (DFG).

PY - 2020/3

Y1 - 2020/3

N2 - Main conclusion: Swelling of sweet cherry cell walls is a physical process counterbalanced by turgor. Cell turgor prevents swelling in intact cells, whereas loss of turgor allows cell walls to swell. Abstract: Swelling of epidermal cell walls precedes skin failure in sweet cherry (Prunus avium) cracking. Swollen cell walls lead to diminished cell:cell adhesions. We identify the mechanism of cell wall swelling. Swelling was quantified microscopically on epidermal sections following freeze/thaw treatment or by determining swelling pressure or swelling capacity of cell wall extracts. Releasing turgor by a freeze/thaw treatment increased cell wall thickness 1.6-fold within 2 h. Pressurizing cell wall extracts at > 12 kPa prevented swelling in water, while releasing the pressure increased swelling. The effect was fully reversible. Across cultivars, cell wall thickness before and after turgor release in two subsequent seasons was significantly correlated (before release of turgor: r = 0.71**, n = 14; after release of turgor: r = 0.73**, n = 14) as was the swelling of cell walls upon turgor release (r = 0.71**, n = 14). Close relationships were also identified for cell wall thickness of fruit of the same cultivars grown in the greenhouse and the field (before release of turgor: r = 0.60, n = 10; after release of turgor: r = 0.78**, n = 10). Release of turgor by heating, plasmolysis, incubation in solvents or surfactants resulted in similar swelling (range 2.0–3.1 µm). Cell wall swelling increased from 1.4 to 3.0 µm as pH increased from pH 2.0 to 5.0 but remained nearly constant between pH 5.0 and 8.0. Increasing ethanol concentration decreased swelling. Swelling of sweet cherry cell walls is a physical process counterbalanced by turgor.

AB - Main conclusion: Swelling of sweet cherry cell walls is a physical process counterbalanced by turgor. Cell turgor prevents swelling in intact cells, whereas loss of turgor allows cell walls to swell. Abstract: Swelling of epidermal cell walls precedes skin failure in sweet cherry (Prunus avium) cracking. Swollen cell walls lead to diminished cell:cell adhesions. We identify the mechanism of cell wall swelling. Swelling was quantified microscopically on epidermal sections following freeze/thaw treatment or by determining swelling pressure or swelling capacity of cell wall extracts. Releasing turgor by a freeze/thaw treatment increased cell wall thickness 1.6-fold within 2 h. Pressurizing cell wall extracts at > 12 kPa prevented swelling in water, while releasing the pressure increased swelling. The effect was fully reversible. Across cultivars, cell wall thickness before and after turgor release in two subsequent seasons was significantly correlated (before release of turgor: r = 0.71**, n = 14; after release of turgor: r = 0.73**, n = 14) as was the swelling of cell walls upon turgor release (r = 0.71**, n = 14). Close relationships were also identified for cell wall thickness of fruit of the same cultivars grown in the greenhouse and the field (before release of turgor: r = 0.60, n = 10; after release of turgor: r = 0.78**, n = 10). Release of turgor by heating, plasmolysis, incubation in solvents or surfactants resulted in similar swelling (range 2.0–3.1 µm). Cell wall swelling increased from 1.4 to 3.0 µm as pH increased from pH 2.0 to 5.0 but remained nearly constant between pH 5.0 and 8.0. Increasing ethanol concentration decreased swelling. Swelling of sweet cherry cell walls is a physical process counterbalanced by turgor.

KW - Cell wall swelling

KW - Cracking

KW - Epidermis

KW - Pectin

KW - Prunus avium

KW - Splitting

UR - http://www.scopus.com/inward/record.url?scp=85079360401&partnerID=8YFLogxK

U2 - 10.1007/s00425-020-03352-y

DO - 10.1007/s00425-020-03352-y

M3 - Article

C2 - 32060652

AN - SCOPUS:85079360401

VL - 251

JO - PLANTA

JF - PLANTA

SN - 0032-0935

IS - 3

M1 - 65

ER -