Institute for Horticultural Production Systems, Leibniz-University Hannover, Herrenhäuser Straße 2, 30419, Hannover, Germany.
Planta. 2020 Feb 14;251(3):65. doi: 10.1007/s00425-020-03352-y.
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. 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.
甜樱桃细胞细胞壁的肿胀是一个由膨压平衡的物理过程。细胞膨压阻止完整细胞的肿胀，而失去膨压则允许细胞壁肿胀。甜樱桃（Prunus avium）裂果中，表皮细胞壁的肿胀先于果皮失效。细胞壁肿胀导致细胞间黏附力减弱。我们确定了细胞壁肿胀的机制。通过冷冻/解冻处理后对表皮切片进行显微镜下定量，或通过测定细胞壁提取物的膨胀压力或膨胀能力来量化肿胀。通过冷冻/解冻处理释放膨压可在 2 小时内使细胞壁厚度增加 1.6 倍。将细胞壁提取物加压至超过 12kPa 可防止在水中膨胀，而释放压力则会增加膨胀。该效果是完全可逆的。在两个后续季节中，在释放膨压前后，不同品种的细胞壁厚度之间存在显著相关性（释放膨压前：r=0.71**，n=14；释放膨压后：r=0.73**，n=14），以及在释放膨压时细胞壁的膨胀（r=0.71**，n=14）。同一品种在温室和田间生长的果实的细胞壁厚度也存在密切关系（释放膨压前：r=0.60，n=10；释放膨压后：r=0.78**，n=10）。通过加热、质壁分离、在溶剂或表面活性剂中孵育释放膨压会导致类似的肿胀（范围 2.0-3.1μm）。随着 pH 值从 2.0 增加到 5.0，细胞壁肿胀从 1.4μm 增加到 3.0μm，但在 pH 值 5.0 到 8.0 之间几乎保持不变。增加乙醇浓度会降低肿胀。甜樱桃细胞壁的肿胀是一个由膨压平衡的物理过程。
