Cell wall swelling, fracture mode, and the mechanical properties of cherry fruit skins are closely related
Cell wall swelling, fracture mode, and the mechanical properties of cherry fruit skins are closely related
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DOI：
10.1007/s00425-016-2639-7
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发表时间：
2017-04-01
期刊：
影响因子：
4.3
通讯作者：
Knoche, Moritz
中科院分区：
文献类型：
--
作者：
Brueggenwirth, Martin;Knoche, Moritz
主要结论甜樱桃果皮的细胞壁膨大、断裂方式(沿中层与跨细胞壁)、硬度和断裂压力密切相关，果皮开裂是许多肉质果实的普遍现象。以甜樱桃(Prunus Avium)为模型，研究了果皮的断裂方式、细胞壁肿胀程度与果皮力学性能之间的关系。裂果是通过在去离子水中孵化整个果实或在双向拉伸试验中断裂外果皮片段(Ess)而引起的。光镜下观察表皮细胞的断裂方式。在双向拉伸试验中，ES的背斜细胞壁主要沿细胞壁断裂(而不是沿细胞壁)，没有显示细胞壁肿胀。相反，在水中孵化的果实主要沿着背斜表皮细胞壁断裂，细胞壁肿胀。当Ess在苹果酸、高渗蔗糖溶液或水中孵育时，也会发生细胞壁肿胀。与未经治疗的对照组相比，这些治疗导致更频繁的细胞壁骨折，更低的骨折压力(p(骨折))，以及更低的弹性系数(E，即不那么僵硬)。相反，与未经处理的对照组相比，在CaCl2和高浓度乙醇中孵育ES会导致细胞壁变薄，沿细胞壁的断裂较少发生，E和p(断裂)较高。我们的研究表明，断裂模式、硬度和断裂时的压力与细胞壁膨胀密切相关。其他一些因素，包括品种、成熟期、膨胀率、CaCl2和苹果酸，只能间接地发挥它们的作用，即通过影响细胞壁膨胀。
Main conclusion Cell wall swelling, fracture mode (along the middle lamellae vs. across cell walls), stiffness, and pressure at fracture of the sweet cherry fruit skin are closely related.Skin cracking is a common phenomenon in many crops bearing fleshy fruit. The objectives were to investigate relationships between the mode of fracture, the extent of cell wall swelling, and the mechanical properties of the fruit skin using sweet cherry (Prunus avium) as a model. Cracking was induced by incubating whole fruit in deionised water or by fracturing exocarp segments (ESs) in biaxial tensile tests. The fracture mode of epidermal cells was investigated by light microscopy. In biaxial tensile tests, the anticlinal cell walls of the ES fractured predominantly across the cell walls (rather than along) and showed no cell wall swelling. In contrast, fruit incubated in water fractured predominantly along the anticlinal epidermal cell walls and the cell walls were swollen. Swelling of cell walls also occurred when ESs were incubated in malic acid, in hypertonic solutions of sucrose, or in water. Compared to the untreated controls, these treatments resulted in more frequent fractures along the cell walls, lower pressures at fracture (p (fracture)), and lower moduli of elasticity (E, i.e., less stiff). Conversely, compared to the untreated controls, incubating the ES in CaCl2 and in high concentrations of ethanol resulted in thinner cell walls, in less frequent fractures along the cell walls, higher E and p (fracture). Our study demonstrates that fracture mode, stiffness, and pressure at fracture are closely related to cell wall swelling. A number of other factors, including cultivar, ripening stage, turgor, CaCl2, and malic acid, exert their effects only indirectly, i.e., by affecting cell wall swelling.