TY - JOUR

T1 - Sweet cherry skin has a less negative osmotic potential than the flesh

AU - Grimm, Eckhard

AU - Knoche, Moritz

PY - 2015/9/1

Y1 - 2015/9/1

N2 - The skin is the primary load-bearing structure in a sweet cherry fruit (Prunus avium L.). Failure of the skin in rain cracking is considered to be related to water uptake. Little is known of the skin’s water potential, its osmotic potential (ΨΠS), and turgor. The objective here was to quantify ΨΠS relative to the osmotic potential of the flesh (ΨΠF). Spatial resolution was achieved by monitoring plasmolysis in epidermal cells in tissue sections, incubated in selected osmotica using a light microscope method. Decreasing the osmotic potential [ΨΠ (more negative)] of the incubation medium increased the proportion (percent) of plasmolyzed epidermal cells. The pattern of increasing plasmolysis was sigmoidal with increasing osmolyte concentration. The value of ΨΠ for 50% of cells plasmolyzed, depended to some extent on the osmolyte used. The value of ΨΠ became slightly less negative for the osmolytes tested in the order: 1) mannitol, 2) sucrose, and 3) artificial cherry juice (a solution comprising the five major osmolytes of sweet cherry juice in the appropriate proportions and concentrations). There was little difference in the value of ΨΠat 50% plasmolysis between the cultivars Hedelfinger, Sam, and Sweetheart. In all three cultivars, the value of ΨΠF (measured for expressed juice using an osmometer) was markedly more negative than that of ΨΠS (measured for 50% plasmolysis). Incubating skin segments in juice from the same fruit resulted in the plasmolysis of most (85.7% to 96.4%) of the epidermal cells. As fruit development progressed from stage II [27 day after full bloom (DAFB)] to the fully mature stage III (97 DAFB), plasmolysis occurred for increasingly more negative values of ΨΠ. Moreover, the difference between the osmotic potential values recorded for the flesh ΨΠF and for the skin ΨΠS increased. Plasmolysis of epidermal cells was accompanied by a marked swelling of their walls. The results indicate a marked difference in the osmotic potential of flesh (ΨΠFtrended more negative) and skin cells (ΨΠS trended less negative).

AB - The skin is the primary load-bearing structure in a sweet cherry fruit (Prunus avium L.). Failure of the skin in rain cracking is considered to be related to water uptake. Little is known of the skin’s water potential, its osmotic potential (ΨΠS), and turgor. The objective here was to quantify ΨΠS relative to the osmotic potential of the flesh (ΨΠF). Spatial resolution was achieved by monitoring plasmolysis in epidermal cells in tissue sections, incubated in selected osmotica using a light microscope method. Decreasing the osmotic potential [ΨΠ (more negative)] of the incubation medium increased the proportion (percent) of plasmolyzed epidermal cells. The pattern of increasing plasmolysis was sigmoidal with increasing osmolyte concentration. The value of ΨΠ for 50% of cells plasmolyzed, depended to some extent on the osmolyte used. The value of ΨΠ became slightly less negative for the osmolytes tested in the order: 1) mannitol, 2) sucrose, and 3) artificial cherry juice (a solution comprising the five major osmolytes of sweet cherry juice in the appropriate proportions and concentrations). There was little difference in the value of ΨΠat 50% plasmolysis between the cultivars Hedelfinger, Sam, and Sweetheart. In all three cultivars, the value of ΨΠF (measured for expressed juice using an osmometer) was markedly more negative than that of ΨΠS (measured for 50% plasmolysis). Incubating skin segments in juice from the same fruit resulted in the plasmolysis of most (85.7% to 96.4%) of the epidermal cells. As fruit development progressed from stage II [27 day after full bloom (DAFB)] to the fully mature stage III (97 DAFB), plasmolysis occurred for increasingly more negative values of ΨΠ. Moreover, the difference between the osmotic potential values recorded for the flesh ΨΠF and for the skin ΨΠS increased. Plasmolysis of epidermal cells was accompanied by a marked swelling of their walls. The results indicate a marked difference in the osmotic potential of flesh (ΨΠFtrended more negative) and skin cells (ΨΠS trended less negative).

KW - Epidermis

KW - Exocarp

KW - Mesocarp

KW - Prunus avium

KW - Turgor

KW - Water potential

UR - http://www.scopus.com/inward/record.url?scp=84942154596&partnerID=8YFLogxK

U2 - 10.21273/jashs.140.5.472

DO - 10.21273/jashs.140.5.472

M3 - Article

AN - SCOPUS:84942154596

VL - 140

SP - 472

EP - 479

JO - Journal of the American Society for Horticultural Science

JF - Journal of the American Society for Horticultural Science

SN - 0003-1062

IS - 5

ER -