TY - JOUR

T1 - Cuticular wax deposition in growing barley (Hordeum vulgare) leaves commences in relation to the point of emergence of epidermal cells from the sheaths of older leaves.

AU - Richardson, Andrew

AU - Franke, Rochus

AU - Kerstiens, Gerhard

AU - Jarvis, Mike

AU - Schreiber, Lukas

AU - Fricke, Wieland

PY - 2005/10

Y1 - 2005/10

N2 - In grasses, leaf cells divide and expand within the sheaths of older leaves, where the micro-environment differs from the open atmosphere. By the time epidermal cells are displaced into the atmosphere, they must have a functional cuticle to minimize uncontrolled water loss. In the present study, gas chromatography and scanning electron microscopy were used to follow cuticular wax deposition along the growing leaf three of barley (Hordeum vulgare L.). 1-Hexacosanol (C26 alcohol) comprised more than 75% of extractable cuticular wax and was used as a marker for wax deposition. There was no detectable wax along the first 20 mm from the point of leaf insertion. Deposition started within the distal portion of the elongation zone (23–45 mm) and continued beyond the point of leaf emergence from the sheath of leaf two. The region where wax deposition commenced shifted towards more proximal (basal) positions when the point of leaf emergence was lowered by stripping back part of the sheath. When relative humidity in the shoot environment was elevated from 70% (standard growth conditions) to 92–96% for up to 4 days prior to analysis, wax deposition did not change significantly. The results show that cuticular waxes are deposited along the growing grass leaf independent of cell age or developmental stage. Instead, the reference point for wax deposition appears to be the point of emergence of cells into the atmosphere. The possibility of changes in relative humidity between enclosed and emerged leaf regions triggering wax deposition is discussed.

AB - In grasses, leaf cells divide and expand within the sheaths of older leaves, where the micro-environment differs from the open atmosphere. By the time epidermal cells are displaced into the atmosphere, they must have a functional cuticle to minimize uncontrolled water loss. In the present study, gas chromatography and scanning electron microscopy were used to follow cuticular wax deposition along the growing leaf three of barley (Hordeum vulgare L.). 1-Hexacosanol (C26 alcohol) comprised more than 75% of extractable cuticular wax and was used as a marker for wax deposition. There was no detectable wax along the first 20 mm from the point of leaf insertion. Deposition started within the distal portion of the elongation zone (23–45 mm) and continued beyond the point of leaf emergence from the sheath of leaf two. The region where wax deposition commenced shifted towards more proximal (basal) positions when the point of leaf emergence was lowered by stripping back part of the sheath. When relative humidity in the shoot environment was elevated from 70% (standard growth conditions) to 92–96% for up to 4 days prior to analysis, wax deposition did not change significantly. The results show that cuticular waxes are deposited along the growing grass leaf independent of cell age or developmental stage. Instead, the reference point for wax deposition appears to be the point of emergence of cells into the atmosphere. The possibility of changes in relative humidity between enclosed and emerged leaf regions triggering wax deposition is discussed.

KW - cell development

KW - cuticle

KW - Hordeum

KW - leaf growth

KW - relative humidity

KW - wax

KW - EPICUTICULAR WAXES

KW - BARRIER PROPERTIES

KW - LEAF SURFACES

KW - ARABIDOPSIS

KW - ELONGATION

KW - GROWTH

KW - DIFFERENTIATION

KW - BIOSYNTHESIS

KW - ACCUMULATION

KW - POLLEN

U2 - 10.1007/s00425-005-1552-2

DO - 10.1007/s00425-005-1552-2

M3 - Journal article

VL - 222

SP - 472

EP - 483

JO - Planta

JF - Planta

SN - 0032-0935

IS - 3

ER -