TY - JOUR

T1 - Epidermal Segments

T2 - A Useful Model System for Studying Water Transport through Fruit Surfaces

AU - Harz, Martin

AU - Knoche, Moritz

AU - Bukovac, Martin J.

PY - 2003/12

Y1 - 2003/12

N2 - Water conductance of the cuticle of mature fruit of apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf., 'Golden Delicious' Reinders/'Malling 9' (M.9)], sweet cherry (Prunus avium L., 'Sam'/'Alkavo'), grape (Vitis vinifera L.), pepper (Capsicum annuum L. var. annuum Fasciculatum Group, 'Jive'), and tomato (Lycopersicon esculentum Mill.) was determined using excised epidermal segments (consisting of epidermis, hypodermis, and some cell layers of parenchyma) and enzymatically isolated cuticular membranes (CM) from the same sample of fruit. Segments or CM were mounted in diffusion cells and transpiration was monitored gravimetrically. Conductance (m·s -1) was calculated by dividing the flux of water per unit segment or CM area (kg·m-2·s-1) by the difference in water vapor concentration (kg·m-3) across segments or CM. Transpiration through segments and through CM increased with time. Conductance of segments was consistently lower than that of newly isolated CM (3 days or less). Conductance decreased with increasing time after isolation for apple, grape, or sweet cherry CM, and for sweet cherry CM with increasing temperature during storage (5 to 33°C for 4 days). There was no significant effect of duration of storage of CM on conductance in pepper or tomato fruit. Following storage of CM for more than 30 days, differences in conductance between isolated CM and excised segments decreased in apple, grape, and sweet cherry, but not in pepper or tomato. Use of metabolic inhibitors (1 mM NaN3 or 0.1 mM CCCP), or pretreatment of segments by freezing (-19°C for 18 hours), or vacuum infiltration with water, had no effect on conductance of apple fruit segments. Our results suggest that living cells present on excised segments do not affect conductance and that epidermal segments provide a useful model system for quantifying conductance without the need for isolating the CM. Chemical names used: sodium azide (NaN3); carbonylcyanide m-chlorophenylhydrazone (CCCP).

AB - Water conductance of the cuticle of mature fruit of apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf., 'Golden Delicious' Reinders/'Malling 9' (M.9)], sweet cherry (Prunus avium L., 'Sam'/'Alkavo'), grape (Vitis vinifera L.), pepper (Capsicum annuum L. var. annuum Fasciculatum Group, 'Jive'), and tomato (Lycopersicon esculentum Mill.) was determined using excised epidermal segments (consisting of epidermis, hypodermis, and some cell layers of parenchyma) and enzymatically isolated cuticular membranes (CM) from the same sample of fruit. Segments or CM were mounted in diffusion cells and transpiration was monitored gravimetrically. Conductance (m·s -1) was calculated by dividing the flux of water per unit segment or CM area (kg·m-2·s-1) by the difference in water vapor concentration (kg·m-3) across segments or CM. Transpiration through segments and through CM increased with time. Conductance of segments was consistently lower than that of newly isolated CM (3 days or less). Conductance decreased with increasing time after isolation for apple, grape, or sweet cherry CM, and for sweet cherry CM with increasing temperature during storage (5 to 33°C for 4 days). There was no significant effect of duration of storage of CM on conductance in pepper or tomato fruit. Following storage of CM for more than 30 days, differences in conductance between isolated CM and excised segments decreased in apple, grape, and sweet cherry, but not in pepper or tomato. Use of metabolic inhibitors (1 mM NaN3 or 0.1 mM CCCP), or pretreatment of segments by freezing (-19°C for 18 hours), or vacuum infiltration with water, had no effect on conductance of apple fruit segments. Our results suggest that living cells present on excised segments do not affect conductance and that epidermal segments provide a useful model system for quantifying conductance without the need for isolating the CM. Chemical names used: sodium azide (NaN3); carbonylcyanide m-chlorophenylhydrazone (CCCP).

KW - Apple

KW - Capsicum annuum

KW - Cuticle

KW - Grape

KW - Lycopersicon esculentum

KW - Malus sylvestris

KW - Pepper

KW - Permeance

KW - Prunus avium

KW - Sweet cherry

KW - Tomato

KW - Transpiration

KW - Vitis vinifera

UR - http://www.scopus.com/inward/record.url?scp=0842280585&partnerID=8YFLogxK

U2 - 10.21273/hortsci.38.7.1410

DO - 10.21273/hortsci.38.7.1410

M3 - Article

AN - SCOPUS:0842280585

VL - 38

SP - 1410

EP - 1413

JO - HORTSCIENCE

JF - HORTSCIENCE

SN - 0018-5345

IS - 7

ER -